Add a make pull to get data back from server

Makefile

@@ -9,5 +9,8 @@ build:
 deploy: build
 	rsync --delete-after -avzP public/ ur.gs:capsule/
 
+pull:
+	rsync --delete-after -avzP ur.gs:capsule/ public/
+
 notify:
 	echo "gemini://warmedal.se/~antenna/submit?gemini%3A%2F%2Fur.gs%2Fatom.xml" | openssl s_client -connect warmedal.se:1965 -servername warmedal.se -crlf -brief -ign_eof

content/_index.gmi

@@ -4,7 +4,7 @@ title: "Nick Thomas"
 
 ## Meta
 
-* me@ur.gs
+* mailto:me@ur.gs
 * Alias: lupine
 * Alias: CommunistWolf
 

content/blog/2022-09-30-solar-installed.gmi

@@ -0,0 +1,67 @@
+---
+title: "Solar Installed"
+---
+
+Well, almost. Yesterday they put the scaffolding up, delivered the panels, and got to putting them on the roof. Six are up there, but the remaining three are sheltering in the garage because they didn't bring enough of the railings that connect panels to roof.
+
+Of course they didn't.
+
+The scaffold is now up until at least Wednesday, which is the first day they can come back with more railing to complete the job.
+
+The six panels are, however, functional, and comprise 2.4kWp of generation capacity. Despite only being there from 2pm, they generated ~3.4kWh yesterday. Today was foggy and overcast, but they managed another ~1.4kWh. Tomorrow and Sunday are looking pretty sunny, but October is hardly peak generation time. Still, according to PVCalc, I can expect an average of 5.23kWh/day in October once the remaining panels are up - nearly half our average daily usage. This lines up with the generation projection the solar survey came up with too.
+
+=> https://joint-research-centre.ec.europa.eu/pvgis-photovoltaic-geographical-information-system/getting-started-pvgis/api-non-interactive-service_en PVCalc
+
+Using the generated energy is the challenge. Of that 3.4kWh, I exported 2kWh - over half. Since there are no batteries right now, I need electricity loads in the house to soak up the solar as it's being generated, or some means of storing it. Energy in the UK is bucketed into half-hour billing periods, so generation and use don't have to match exactly, but it's frustrating to see a big energy use peak right next to a bucket where 0kWh was imported.
+
+## Regrets
+
+One of the electricity loads I have is an "iBoost", which is meant to turn on the immersion heater, bypassing the heat pump entirely, if there's excess generation. Charging the thermal store (hot water cylinder) at a CoP of 1 is pretty rubbish, but - economically speaking - better than exporting to the grid if you're getting paid peanuts to do so. For me, the device is pointless, but it's installed. At least I can turn it off.
+
+It seems that there might be room for fifteen panels on the roof, but the installers are refusing to install capacity over the G98 limit of 3.68kWp, even if the export is inverter-limited to that amount. So the scaffold will probably be going back up next year, but adding six, rather than three, panels, makes it more worthwhile. In retrospect, there was time to get the G99 application in to have more installed in a single go - although permission is not guaranteed, so perhaps this was the correct route after all.
+
+It's also occurred to me that my shiny new heat pump is plumbed in wrongly for a house with solar PV. Leaving aside the fact that it would have been wise to get solar thermal as well, it would be better if the heat pump exclusively heated the hot water cylinder, and the cylinder was used to drive the central heating as well as domestic hot water. This would allow me to avoid switching the pump on at night, when there is no solar, but would probably have required the cylinder to be much larger than it is. It's all good learning for the next house, though.
+
+## Buffering
+
+The cylinder is a thermal store, but not a large one, and not plumbed for maximum utility. However, the "grid as battery" idea that I talked about in "Off-grid in Suburbia" is looking better and better. I'm switched over to Octopus, from E.on (who were giving 3p/kWh for export). Once all the paperwork is done, I can either choose a guaranteed 15p/kWh (just increased!), or use "Agile Outgoing", with prices ranging anywhere from nothing to > 60p/kWh, depending on demand and time of use.
+
+=> /blog/off-grid-in-suburbia/ Off-grid in Suburbia
+=> https://www.energy-stats.uk/octopus-agile-outgoing-export-yorkshire/ Octopus export tariff prices
+
+Since I can't shift my generation (via batteries) to the highest-priced times, the fixed rate is probably the right one for me. It's still 5x the price my previous supplier was offering, and is high enough to obsolete the iBoost. The heat pump has a CoP of ~3.5; when it's running on imported energy (~33p/kWh), this means each kWh of heat costs ~9.4p. The iBoost, running on generated solar with CoP=1, has a notional cost of 15p/kWh, so using it is the same as throwing away ~5.6p/kWh. 
+
+Batteries can be added next year, but definitely not this year. I'll probably attempt to DIY it on the DC side; the batteries can then discharge when there isn't any solar, or when I want to export, through the existing inverter, without DNO involvement. I need to start being more hands-on with this stuff. Only without getting electrocuted.
+
+Buffering is about moving the energy to time of use; taking the same problem from the opposite side, we can move the time of use instead, which leads to:
+
+## Reasonable Home Automation
+
+It feels like that house is far more connected to the elements now it has solar panels. Suddenly, it's beneficial to take local conditions into account when using energy.
+
+For example, the heat pump is currently programmed to heat the cylinder between 12-1pm each day. When running directly off of solar, we can divide the export price by the CoP to arrive at a notional cost: 4.2p/kWh - less than half the cost of running it off imported energy. If it's cloudy at midday but sunshine is forecast for 4pm, it makes sense to delay running the pump until then, so it can take advantage.
+
+Similarly, we have "set-back" crudely configured into the thermostat at the moment - the temperature is allowed to drop from 21'C to 18'C between 9pm and 7am. These are very arbitrary, though, and I often find the pump is running at 8:30pm because temperatures have dropped to 20.8'C or so. Having the thermostat take sunrise and sunset into account, and having it progressively ramp setback up and down rather than it being a cliff edge, makes sense. So does allowing the temperature to drift a little (above or below 21'C) depending on current and predicted solar availability.
+
+There are more conventional examples too, like running conventional appliances while it's sunny, but for 4-6 months of the year, the heat pump is the single biggest energy user, so I'm focusing on that. (The second-largest appears to be cooking, which I'm ignoring for now, but changing the time you cook dinner is entirely feasible without any automation).
+
+All this is solved with "smart home" gadgetry, but sadly, those gadgets are of the "upload everything to the cloud" variety. I'm dipping my toes into more-reasonable approaches, and have the bones of a plan:
+
+=> https://shop.electrolama.com/collections/usb-rf-sticks/products/zzh-multiprotocol-rf-stick ZigBee zhh coordinator module in the home server
+=> https://shimmeringbee.io/ ShimmeringBee coordinator software (ZigBee + MQTT) running on the home server
+=> https://www.develcoproducts.com/products/meter-interfaces/external-meter-interface/ ZigBee pulse counter on the generation meter
+=> https://shop.glowmarkt.com/products/display-and-cad-combined-for-smart-meter-customers Glow "CAD" add-on to get (local, not cloud) MQTT feeds for the import + export meter
+=> https://github.com/aerona-chofu-ashp/modbus Scrape the heat pump's Modbus interface and get it into ShimmeringBee somehow
+
+That should be enough to get me the data I need to calculate scenarios like the ones above. "All" I have to do then is enrich it against internet-available data (weather predictions, say), make decisions automatically, with the potential for some human input too, and have them be implemented by hardware.
+
+These things need coordinator software. ShimmeringBee is a bit of a find, being a tiny Go daemon without any kind of UI. Trivial to deploy, trivial to modify, I glommed onto it as soon as I found it.
+
+Lots of other options, but I'm going to stick with it to begin with, even though I'm going to have to write code to get most of the items above talking to it. At least the zzh coordinator works out of the box. It has an MQTT port open too, so hopefully the import/export meter will work fine. The decision code can just go straight into the daemon, I think.
+
+=> https://ubidots.com/blog/open-source-home-automation/ Other options
+
+I don't have hardware for implementing decisions planned out yet. So much of it is going to be around the heating system. A thermostat I can control from ShimmeringBee will be the first requirement, possibly along with ZigBee-connected TRVs, so rooms can be heated or not individually.
+
+It's a techy dream (nightmare?), but the underlying goal is to get the house using less energy. Of course, all this tech *uses* energy, but I'll be doing my best to keep that aspect under control, mostly through careful selection of low-power components and software. At least the glue is code I'm looking forward to writing!
+

content/blog/2022-10-10-battery-time.gmi

@@ -0,0 +1,81 @@
+---
+title: "Battery time"
+---
+
+In my last post I talked a little bit about the newly installed solar panels, and a lot about home automation. Since then, the solar install has been completed, although the scaffolding is still up (grumble grumble). I have nine panels on the roof, and today was a new generation record - 17.1kWh, with 4kWh of import from the grid!
+
+=> /blog/solar-installed/
+
+Of course, we didn't use 21.1kWh overall; instead, we exported a large amount of it. For free, since I don't yet have the paperwork required to sign up to an export tariff.
+
+## Reasonable Home Automation (cont)
+
+The sensors part of the home automation project is going pretty well; I have data from:
+
+* Air quality sensor via ZigBee zhh adapter
+* Glow CAD
+* Solax DC->AC solar inverter
+
+All of this is being fed into MQTT (the mosquitto server), then exported into victoria-metrics via mqtt2prometheus. The CAD speaks MQTT natively; the air quality sensor is currently being filtered through zigbee2mqtt on the laptop while ShimmeringBee gets support for that specific device; and the Solax inverter is being scraped via some custom code I put together. More on that shortly.
+
+With the time series in victoria metrics, I can generate pretty dashboards in grafana at will:
+
+=> /img/battery-time/power-dashboard-1.png Power Dashboard part 1
+=> /img/battery-time/power-dashboard-2.png Power Dashboard part 2
+=> /img/battery-time/sensors-dashboard.png Air Quality Sensor dashboard
+
+
+(The spike on that last one is me breathing into the sensor to prove it worked.)
+
+## Solax inverter deep dive
+
+Being able to scrape the inverter was a bit of a surprise - the plan was a Zigbee pulse counter on the generation meter. When the installers put the inverter in, however, they equipped it with a hideously insecure and hostile "PocketWIFI" module, which acts as both a WIFI AP and client. The AP is unsecured and cannot be turned off, but the client can at least do WPA2-PSK, and is connected to a WIFI Home Automation Network I've set up with no internet.
+
+Either way, once you've got an IP address for the adapter, you can query it over HTTP and get data about the inverter it's plugged into. It's also listening on port 502 (Modbus-TCP), although I've not managed to get it to respond to anything mbpoll can send. Still, it's slightly scary to think that anyone in the vicinity of my house can speak modbus directly to the inverter by connecting to the unsecured AP.
+
+If this is what they put in someone's house when they explicitly request Luddite mode, I can't imagine what "full cloud connectivity mode" looks like.
+
+The adapter also tries to connect to an MQTTS (TLS, port 8883) server in The Cloud. This is used for aforementioned cloud connectivity and offers exciting features like "push arbitrary firmware to the inverter/adapter", alongside "view your inverter data with a 5-minute delay". Of course, they're not verifying certificates, so the MQTTS connection is trivial to hijack for harvesting data - or pushing said arbitrary firmware.
+
+Programmes like "Leverage" present hackers as modern-day wizards, able to do anything with any computer, take over any system, and exert absolute control over network-connected devices. It seems far-fetched until you run into actual real-world systems like this...
+
+Anyway, the plan is to replace the "PocketWIFI" module - either with a direct Modbus-RTU connection, as with the heat pump, or with a "PocketLAN" device if that proves infeasible. Both are significantly more secure, since they require physical access to take over the device.
+
+Meanwhile, the MQTTS stream proved to be inconveniently formatted for use with matt2prometheus, since it pushes binary data rather than JSON. I removed the interceptor and knocked together a tiny bit of code that scrapes the HTTP endpoint instead.
+
+This gives a JSON response that contains a 100-element array of uint16 values, which is the sensor/status data. There's a lot of Solax projects and integrations already that had made headway on interpreting this in general, but none for my specific inverter/firmware combination, so I got to do some detective work, helped along enormously by the squishykid/solax GitHub project. The result is solax2mqtt, a small (ca. 250LOC) Rust program that does the HTTP scrape, transform, and MQTT push, all in one.
+
+=> https://github.com/squishykid/solax/issues/93 squishykid/solax issue 93
+=> https://code.ur.gs/lupine/solax2mqtt Solax->MQTT project
+
+It's been a while since I've written anything in Rust, and this was an easy project, but I enjoyed it greatly and managed to get into a tight loop with the compiler to build out the whole thing without once running it against the actual inverter. Once the compiler was happy, and all my TODOs had been implemented, I did that and it worked first time, with no bugs, which was a great feeling. I should do more in Rust.
+
+Despite all the data, I don't yet have a reliable export number. I do have live export in watts, but not accumulated kWh, despite both the inverter and glow CAD being able to provide it in theory. Perhaps it will start working once I'm signed up to an export tariff.
+
+## Batteries
+
+Anyway, the sensor data makes two things very clear to me:
+
+* I should install MVHR
+* I should install a battery system
+
+The first point will be the subject of another article. The second follows from the energy stats, but there are a few other considerations.
+
+First, sizing, efficiency, and pricing - I'm looking at a 3.3kWh system (DIY-expandable in 3.3kWh modules), which will have ~90-95% efficiency and cost around £3750, fully installed. This has to compete with the grid, which, per my previous post, has infinite capacity and is free, but only has ~50% efficiency when round-tripping through money at current unit prices.
+
+My original plan was to leave thinking about batteries until next year, and only to do it in conjunction with a larger solar array. Since then, the UK has started talking about 3-hour rolling blackouts over winter (perhaps a 10% chance of this happening), and paying people £10/day to avoid using energy from the grid 4pm-7pm (much higher chance of this happening). The former affects me far more than it should - I've spent enough time without electricity, thank you - but the latter is very helpful.
+
+The no-grid bribe from November - February would be £1,200 - and much easier and more pleasant to collect with a battery installed. If it extended into March as well, that would be £1,500 - 40% of the total cost of the battery, in just five months.
+
+The more traditional benefit is that overnight usage can come from the battery, reducing daily import. Assuming I avoid 3kWh/day of import, the saving is £0.50/day compared to the grid-battery option. It really puts the size of that 4pm-7pm bribe into perspective! Paying back the remaining 60% of the battery cost from that would take 12 years - and the battery is only rated to last for ten. Without the grid bribe? 28 years for full payback.
+
+The no-grid scenario exercises me greatly, though. Without the battery system, the solar panels are useless - the inverter has "anti-islanding protection", which prevents line workers from getting fried by shutting the panels down. The house is also much more dependent on electricity now that it's powered by a heat pump (although it's worth noting that gas boilers do need a small amount of energy to function, although it could conceivably be provided with a plug-in UPS).
+
+The batteries we're looking at are AC-coupled and provide an "EPS" circuit - basically a UPS. Most of the time, the circuit is powered by the mains, but the batteries can put 3kW of power into it if the grid goes down. The heat pump, home server + internet + HAN, lights, and a couple of sockets in the kitchen, can be powered from there.
+
+Without solar, 3kW of load would empty the batteries in 1 hour, but the batteries allow the solar to keep working, so there's up to 3kW of power flowing into the system. On a good day, it could run for long as the sun is shining, plus the capacity of the battery. Load is also likely to be less than peak - overnight, including the heat pump set to 18'C, we do about 100W at current temperatures. On a cold winter's day, with the heat pump maintaining 21'C, we might do 500W before taking cooking into account, so the battery covers us for six hours. I suppose we could always turn the heat pump off to extend it further, but I've also had enough of being cold.
+
+So, despite the poor payback calulation, we're still getting them. Being able to function without the grid is more important than having them pay for themselves, even if the grid has a 90% chance of making it through winter unscathed. I look forward to writing more rust to scrape this inverter, too! I'll place the order tomorrow; the plan is to get it all done before November. Since the scaffolding is still up, Switched On won't be getting this contract; instead, I'm giving Big Green Beard a go.
+
+=> https://www.biggreenbeard.co.uk Big Green Beard
+

content/blog/2022-11-25-finished.gmi

@@ -0,0 +1,44 @@
+---
+title: Finished
+---
+
+Batteries are finally in. I ended up going a different route to the one planned in my last post; it turns out that it's actually quite hard to get an AC-coupled battery system that permits the solar PV to keep running when the grid is down. I found an article describing four different "levels" of grid independence; actually getting someone to fit, say, "Manual Whole House Backup" is just... difficult.
+
+=> /blog/battery-time/ Battery Time
+=> https://www.deegesolar.co.uk/eps_for_solar/ EPS for solar PV
+
+So I rethought, and decided to replace the existing Solax inverter with a Lux Power hybrid inverter and make do with a simple EPS socket. Since the PV and batteries are both DC-side, it's trivial to charge the battery from the panels this way. Removing the Solax inverter also felt good from a security perspective, since the Lux allows you to disable both the wifi AP and call home functionality.
+
+Price-wise, it was fine - the hybrid is only a little more expensive than the AC-coupled inverter would be, and the Solax is now a spare that I can use for... well, I'll find a use for it. My sister wouldn't mind a ground-mounted solar PV install, it could be the hub of that.
+
+Big Green Beard didn't come through for us in the end - they took the order details and then never got back in touch, despite several follow-ups. No matter. I found another distributor (Home Energy Group), and got an LXP3600 Hybrid with a 3.2kWh "Greenlinx" battery. Price transparency on the website was nice to have; overall a recommend.
+
+=> https://homeenergygroup.co.uk/lux-hybrid-battery-storage-greenlinx/ Home Energy Group hybrid package
+
+Lead times were about a month; it finally went in yesterday, and it looks like it'll do the trick nicely. Today was a sunny autumn day, so we got to see it properly in action:
+
+=> /img/finished/power-use.png
+
+The yellow line is generation, while the red line is "power from the inverter" - which may come from PV or the battery. Green is imported power. The battery went from 10% to 100% charge between 9am and 2:30pm (not shown), then supported power use, keeping import down, until it ran dry around 17:30pm. After 2:30pm, a small amount of energy went to export (also not shown) but we captured most of what we generated. It was a heavy energy use day for us - dishwasher, washing machine, and dryer all ran in the afternoon - but we've kept the day's import to ~6kWh.
+
+This inverter series has a nice, pre-existing project for local metrics and control, which is surprisingly similar to my solax2mqtt project in concept - lxp-bridge. Written in rust, it polls the inverter and converts what it finds into mqtt messages. It's much further advanced, though, and supports sending the inverter commands (e.g., "charge from AC"), has some home-assistant auto-discovery support, and can push the metrics out using the InfluxDB v1 API (which Victoria Metrics supports natively). Once I got it set up, it was pretty simple to cut over my existing graphs to support it.
+
+=> https://github.com/celsworth/lxp-bridge lxp-bridge
+
+The status value is a bitfield, which was fun to work out how to support in grafana. I ended up with this visualisation:
+
+=> /img/finished/status-display.png Status display
+
+"FAULT" and "GRID OFF" will turn red if the bit flips, while the rest toggle between nothing and green. It's pretty handy.
+
+This inverter also happens to send grid import and export numbers (it has a CT clamp wired in), so the Glow CAD may be obsolete, which would simplify matters. Haven't quite gotten around to disconnecting it yet, though.
+
+The EPS circuit is up in the loft, it's just a simple double socket at the moment. I'll get that expanded to be a minimal consumer unit that takes over the lights, at minimum, when I can; if there's a grid outage in the meantime, I've got an extension cable I can run through the loft hatch. Given the difficulty of using the EPS, the capacity is fine for power cuts lasting multiple hours; it'll keep the lights and internet on for ages, and we could even microwave food! The UK is currently operating with a worst-case scenario assumption of a week-long powercut, but my approach to that is a bit more low-tech - we've got some wood stored in the garage, and a chiminea to burn it in. From that we can heat water for hot water bottles and/or cluster around it for warmth.
+
+Given peak solar generation in winter just about fits in this battery, I've forbidden myself from getting any more until at least spring (HEG sell them for £1550 per 3.2kWh unit). I should be able to DIY the install, as well. Famous last words.
+
+3.2kWh is also enough to completely remove any grid import during Octopus "saving sessions", which is what the no-grid bribes have been branded as. Currently they're £2.25/kWh and they calculate reductions against a baseline derived from your import in the preceding days, which makes big payouts harder than I thought. They're also relatively infrequent; there have only been two in November so far. Still, the batteries were never going to be a winning financial proposition.
+
+The one remaining outstanding thing is getting paid 15p/kWh for export, which allows me to treat the grid as a 50% efficient battery - I finally got all the paperwork relating to the solar installation over to Octopus. They're doing the necessary behind-the-scenes work, and in perhaps a couple more weeks I'll be getting paid. That makes the PV diverter useless, but I've already turned it off anyway as it's much better to store the power in the battery until the heat pump needs it.
+
+tl;dr: lots of learning, lots of waste, but I'm finally done with making changes to this house for the year. I am, in fact, finished!

content/blog/2023-01-08-2022-2023-review.gmi

@@ -0,0 +1,37 @@
+---
+title: "2022 - 2023 Review"
+---
+
+## 2022
+
+About this time last year, I put together a post detailing some projects for 2022. Now is a fine time to go back and see how I've done with them.
+
+=> /blog/projects-for-2022/ Projects for 2022
+
+I don't fancy itemising, but the big trend is that very little of what I wrote down got done, especially when it comes to software. I can fairly reliably blame parenting for that, but my two biggest personal projects - ordoor and purple-plugin-delta - are both stalled on identical issues: the big rust rewrite. I suspect managing to kick-start one will also kick-start the other, it's just a matter of making it happen.
+
+Life stuff has gone significantly better; in particular, we're now very well settled in Yorkshire, in a house that's not falling down. We still have the Shetland house, but that should be going early this year - there's just a tiny bit of additional work that's waiting for a break in the weather.
+
+Body projects got absolutely no traction! Likewise the visit to Cuba. I kept up the Spanish though.
+
+I withdrew from the MSc - although building our own sustainable house is still a big medium-term goal, we've decided to tackle it in a more hands-on, less academic way. Part of that is the new projects with heat pumps and solar panels and batteries I took on last year; there will be other projects this year in a similar vein. I'm on the lookout for land too - I figure I can pick it up before we're ready to build, if something idyllic comes along.
+
+Lots of other things were not planned, but happened anyway, last year, such as the new job, getting the allotment, and sorting various things with my sister's house. I did a pretty good job of writing about them as they happened, so a recap doesn't add much.
+
+Overall, I'd give myself a solid 7/10.
+
+## 2023
+
+This year has a lot less structure in it than 2022. The code and body projects can carry over, but I need to identify a new approach for getting stuck into them.
+
+In the current house, we plan to switch to underfloor heating. This has two benefits - we can squeeze much more efficiency out of the heat pump, and it allows me to throw away the carpets and mandate hard flooring throughout. This will be a huge hygiene win - carpets do not mix with babies, pets, or reluctant housekeeping, and we have all three. Once they're down, we can get a robot hoover again.
+
+The allotment and garden will continue this year. We've got a tentative plan for the food we want to grow, which involves a gigantic maize stand and needs me to start some aubergine seeds this month. It won't be self-sufficiency - we don't have the space - but if we can get a third of our vegetables from this plot, we'll be doing well.
+
+I'm thinking about making the garden more baby-friendly with additional decking, but that's still tentative.
+
+A stretch goal is converting the garage into a utility room and snug. Doing all the planning, design, and build ourselves will make for a good learning experience, but it's a big project and starting it might well slip to 2024.
+
+The masters just isn't happening, but I have my eye on a couple of CAT "short" courses (each is a week long, on-site down in Wales) - one is straw-bale building, the other is sustainable woodland management, and building a straw bale house in a forest is absolutely in my wheelhouse. I should get to go to both courses, and we can twin them with holidays in Wales. It's not Cuba, but it is something of a Mecca of sustainable development here in the UK.
+
+On we go.

content/blog/2023-01-13-free-markets.gmi

@@ -0,0 +1,7 @@
+---
+title: Free markets
+---
+
+One word: Turgot.
+
+Economic distribution must always have a moral component. Otherwise the outcomes will be immoral. Actively advocating for that would be, well, bad.

content/blog/2023-01-14-allotment-plan-2023.gmi

@@ -0,0 +1,22 @@
+---
+title: "Allotment Plan: 2023"
+---
+
+This year, I'm going to do some high-intensity growing on the allotment, following a pretty relaxed quarter-year in 2022 where I just cut back overgrowth and harvested things put in by the previous owner.
+
+=> /img/allotment-plan-2023.png Allotment schematic
+=> /blog/allotment/ Previous allotment post
+
+The three greenhouses will be taken up for the year with tomatoes, peppers, and aubergines. The field will be sweetcorn, and the long bed will be borlotti beans. Spread about the raised beds will be leeks, kale, squash, and spring onions wherever I find myself with a a free spot. There's some extra fruit not shown - at home, a respectable strawberry bed and apple tree. At the allotment, currant bushes and a cherry tree. I might add a few more fruit trees in pots, as well.
+
+The aubergine seeds went into the airing cupboard today. They need a good constant 21°C heat to germinate, and there's only twenty of them, so I'm taking no chances. If all goes well, those seeds will yield 100-120 aubergines in September - about 5,000-6,000kcal. I wouldn't be eating them all in a couple of days, though; they can be preserved in oil, or dehydrated.
+
+The field will be the sweetcorn stand; I don't have to do anything with that until March or so. It should yield ~300 ears of sweetcorn, giving a respectable 25,000kcal which can be frozen.
+
+Everything else contributes fairly small amounts of energy, with the exception of the fruit. Adding it all together, we might have fruit and vegetables for the whole family for around 12 weeks, putting me maybe 5 weeks short of the one-third target.
+
+I've thought about adding a fourth greenhouse to the garden at home, which would give me somewhere to grow rocket and other salad staples. That could make (some of?) the difference.
+
+A lot of the allotment is unproductive - grass, woodchips, hard standing, the parking space... I can probably eke out some more growing space there too, and there's also the chance of a turnip crop (the purple and white ones, not the yellow things we call swedes) after the sweetcorn comes up. I don't like turnips, though!
+
+The traditional saying is an acre per person for self-sufficiency; given I'm working with about 6% of that, it feels like a decent effort. Assuming the slugs and pigeons don't get it all!

content/blog/2023-04-16-aubergine-madness.gmi

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+---
+title: "Aubergine madness"
+---
+
+Over the last three months, my aubergines seeds have been developing into plants. 19/20 germinated. 3 of them failed early, and the remaining sixteen have been growing vigorously on the south-facing windows of the house. I was surprised to learn that they can be quite thorny.
+
+=> /img/aubergine-madness/sill.jpg
+=> /img/aubergine-madness/flower.jpg
+
+This was a bit of a race with the weather; aubergines can't go in an unheated greenhouse until the frosts are over, and ideally it'd be 10°C overnight. In the end, I put them into the greenhouse this week - we're generally at 5°C overnight, and we had simply run out of space on the windowsills. Six were already living in a little greenhouse in the back garden during the day, coming inside whenever the weather turned bad. So, here they are, all planted out:
+
+=> /img/aubergine-madness/resting-place.jpg
+
+It remains to be seen how well they respond to their new living conditions. A couple seem to be struggling to take in water; if I lose them, my success rate drops from 80% down to 70%, so fingers crossed for them. My babies!
+
+The aubergines aren't the only thing happening on the allotment, though. The sweetcorn field is uncovered and ready to go next month; I've built a frame for the beans to grow up, and will plant them this month; onions and leeks are in; the rhubarb is coming through strongly; the raspberries are full of life. I've also got a large number of tomato seedlings, and a smaller number of peppers, ready to go to the allotment to pot on / plant out.
+
+=> /img/aubergine-madness/field.jpg
+=> /img/aubergine-madness/more-seedlings.jpg
+=> /img/aubergine-madness/bean-cage.jpg
+
+Less positively, the asparagus appears to be dead. I wonder if I killed it by cutting back earlier than I should have last year, or mulching too heavily. Perhaps it was doomed not to survive the winter, no matter what I did.
+
+I've also discovered that we have couch/twitch, which is a sterile grass that spreads through some pretty ridiculous rhizomes. It's awful to root crops and not great for anything else either. In a non-glyphosate plot, the best option is to fork it up and pick the rhizomes out of the soil. You can't catch them all, of course, so you have to do this every time you see a new blade of grass come up. It's pretty time-consuming, but I'm making progress. The aubergine greenhouse was previously overrun, and so was the leek bed, and they're both usable now.
+
+Onwards!

content/blog/2023-04-20-codigo-penal-de-cuba-translation.gmi

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+---
+title: "Codigo Penal de Cuba: translation"
+---
+
+It being the 20th April, I was curious about the status of drug laws in Cuba. It seems they're defined in the Penal Code (Codigo Penal), which was updated in 2022. I couldn't find an English translation offhand, so here's my manual attempt for the relevant section.
+
+=> https://www.gacetaoficial.gob.cu/sites/default/files/goc-2022-o93_0_0.pdf Official PDF of the Penal Code of Cuba (2022 edition)
+=> /pdf/goc-2022-o93_0_0.pdf Local mirror
+
+My spanish is still pretty poor, and I have no particular experience at translations or Spanish legal forms, but it's good to exercise like this. I might try to put together a quality translation of the whole at some point - although not as a blog post.
+
+Corrections welcomed! Obviously, don't rely on this translation for anything where an inaccuracy might matter.
+
+## Español
+
+SECCIÓN CUARTA
+
+Delitos relacionados con las drogas ilícitas o sustancias de efectos similares.
+
+Artículo 235.1. Incurre en sanción de privación de libertad de cuatro a diez años, quien
+sin estar autorizado:
+
+a) Produzca, elabore, transporte, trafique, adquiera, introduzca o extraiga del territorio nacional o tenga en su poder, con el propósito de traficar o, de cualquier modo, procure a otra persona, drogas ilícitas o sustancias de efectos similares;
+
+b) opere, administre o dirija locales o viviendas destinados a la concurrencia de personas para consumir drogas ilícitas o sustancias de efectos similares;
+
+c) fabrique, transporte, o distribuya equipos, materiales o sustancias precursoras a sabiendas que se utilizan en el cultivo, producción o fabricación ilícita de drogas ilícitas o sustancias de efectos similares;
+
+d) cultive la planta Cannabis, conocida por marihuana, u otras de propiedades similares o, a sabiendas, posea semillas o partes de dichas plantas;
+
+e) mantenga en su poder u oculte, sin informar de inmediato a las autoridades, los hallazgos de drogas ilícitas o sustancias de efectos similares; y
+
+f) organice, gestione o financie las acciones o actividades previstas en este apartado.
+
+2. La sanción es de privación de libertad de diez a treinta años, privación perpetua de libertad o muerte:
+
+a) Si los hechos a los que se refieren los apartados anteriores se cometen por funcionarios o empleados públicos, autoridades o sus agentes o auxiliares, o estos facilitan su ejecución, aprovechándose de esa condición o utilizando medios o recursos del Estado;
+
+b) si la persona, en la transportación o tráfico ilícito internacional de drogas ilícitas o sustancias de efectos similares penetra en territorio nacional por cualquier circunstancia, utilizando nave o aeronave u otro medio de transportación;
+
+c) si la persona participa en actos relacionados con el tráfico ilícito internacional de drogas ilícitas o sustancias de efectos similares;
+
+d) si, en la comisión de los hechos previstos en el apartado anterior se utiliza persona menor de dieciocho años;
+
+e) si los hechos descriptos en el apartado 1 se cometen en instituciones educativas, deportivas, establecimientos penitenciarios u otros lugares de internamiento, centros asistenciales o en sus inmediaciones o en otros lugares a los que los niños, niñas, adolescentes y jóvenes acudan para realizar actividades educativas, deportivas y sociales;
+
+f) si los hechos se cometen vinculados a un grupo organizado o a la delincuencia organizada transnacional;
+
+g) si los hechos se realizan con cantidades relativamente grandes de drogas ilícitas o sustancias de efectos similares; y
+
+h) si el responsable al momento del hecho, tiene registrado un antecedente penal por similar delito, sea por tribunal nacional o extranjero.
+
+3. Quien, al tener conocimiento de la preparación o ejecución de cualquiera de los delitos previstos en este artículo, no lo denuncie, incurre en sanción de privación de libertad de dos a cinco años.
+
+4. Los actos preparatorios de los delitos previstos en este artículo se sancionan conforme a lo dispuesto en el Artículo 77 de este Código.
+
+5. A los declarados responsables por cualquiera de los delitos previstos en este artículo se les impone, si procede, la sanción accesoria de confiscación de bienes; y en el caso previsto en el inciso d) del apartado 1 que antecede, si el cultivador es propietario, usufructuario u ocupante por cualquier concepto legal de tierra, se le impone la confiscación de esta en el primero de los casos, y en los demás se le priva del derecho de usufructo u ocupación de la misma.
+
+Artículo 236. La simple tenencia de drogas ilícitas o sustancias de efectos similares sin la debida autorización o prescripción facultativa, se sanciona:
+
+a) Con privación de libertad de uno a tres años o multa de trescientas a mil cuotas o ambas, cuando se trate de cocaína o de otras sustancias de efectos similares o superiores;
+
+b) con privación de libertad de seis meses a dos años o multa de doscientas a quinientas cuotas o ambas, cuando se trate de Cannabis, conocida por marihuana, o sus derivados; y
+
+c) con privación de libertad de seis meses a un año o multa de cien a trescientas cuotas o ambas, cuando se trate de drogas ilícitas o sustancias de efectos similares no comprendidas en los apartados anteriores.
+
+Artículo 237.1. Se sanciona con privación de libertad de tres a ocho años:
+
+a) Al profesional que, autorizado para recetar o administrar drogas ilícitas o sustancias de efectos similares lo haga con fines distintos a los estrictamente terapéuticos; y
+
+b) a quien, por razón del cargo o empleo que desempeñe, y a consecuencia de infringir las disposiciones legales o reglamentarias a que está obligado, permita la introducción o tránsito en el país, o la extracción de este, de drogas ilícitas o sustancias de efectos similares.
+
+2. Si los hechos previstos en el apartado anterior se realizan en cantidades relativamente grandes de las sustancias referidas, la sanción es de privación de libertad de cuatro a diez años.
+
+Artículo 238. Quien infrinja las medidas de control legalmente establecidas para la producción, fabricación, preparación, distribución, venta, expedición de recetas, transporte, almacenaje o cualquier otra forma de manipulación de drogas ilícitas o sustancias de efectos similares se sanciona con privación de libertad de seis meses a dos años o multa de doscientas a quinientas cuotas, o ambas.
+
+## English
+
+SECTION FOUR
+
+Crimes related to illegal drugs or substances with similar effects.
+
+Article 235.1. Whoever without authorization does any of the following incurs the sanction of imprisonment for of four to ten years:
+
+a) Produces, makes, transports, traffics, obtains, introduces or removes from the national territory or has in their possession, with the intention to traffic or, in any way, obtains for another person, illegal drugs;
+
+b) operates, manages or runs premises or dedicated houses to the public for people to consume illegal drugs or substances with similar effects;
+
+c) makes, transports, or distributes equipment, materials, or precursor substances to be knowingly used in the cultivation, production or illegal fabrication of illegal drugs or substances with similar effects;
+
+d) cultivates the Cannabis plant, also known as marijuana, or others with similar properties or, knowingly, possesses seeds or parts of said plants;
+
+e) keeps on their person or hides, without immediately informing the authorities, the finding of illegal drugs or substances of similar effects; and
+
+f) organises, manages or finances the actions or premeditated activities in this section.
+
+2. The sanction is imprisonment for ten to thirty years, life imprisonment or death:
+
+a) If the acts that are referred to in the previous sections are committed by civil servants or public employees, authorities, or their agents or assistants, or they facilitate their execution, take advantage of that condition or using means or resource of the state;
+
+b) if the person, in the transportation of illegal international trafficking of illegal drugs or substances with similar effects enters the national territory under any circumstance, by ship or airplane or another mode of transportation;
+
+c) if the person participates in acts related to the illegal international trafficking of illegal drugs or substances with similar effects;
+
+d) if, in the commission of the planned actions in the previous section they make ue of people younger than eighteen years;
+
+e) if the acts described in section 1 are committed in educational institutions, sports clubs, penal establishments or other places of internment, aid centres or in their surroundings or in other places that boys, girls, adolescents and young people attend to carry out educational, sports and social activities;
+
+f) if the acts are committed linked to an organised group or to organised transnational crime;
+
+g) if the acts are carried out with relatively large quantities of illegal drugs or substances with similar effect; and
+
+h) if the responsible person at the moment of the act has a previous conviction for a similar crime, by a national or foreign court.
+
+3. Whoever, having knowledge of the preparation of execution of any of the planned crimes in this article, doesn't report it, incurs imprisonment of two to five years.
+
+4. Preparatory acts of the planned crimes in this article are sanctioned according to what is set out in article 77 of this Code.
+
+5. Those declared responsible for any of the planned crimes provided for in this article wil have imposed on them, if appropriate, the secondary sanction of assets; and in the expected case of subsection d) of part 1 above, if the grower is the owner, beneficial owner or occupying land by any legal concepet, confiscation confiscation of this is imposed in the first case, and in the rest to be deprived of the right of beneficial ownership or occupation of the same.
+
+Article 236. The simple possesion of illegal drugs or substances with similar effects without the necessary authorisation or doctor's prescription, is sanctioned:
+
+a) With imprisonment of one to three years or a fine of three hundred to one thousand (pesos?) or both, when dealing with cocaine or other substances with similar or greater effects;
+
+b) with imprisonment of six months to two years or a fine of two hundred to five hundred pesos or both, when dealing with Cannabis, known as marijuana, or their derivatives; and 
+
+c) with imprisonment of six months to a year or a fine of one hundred to three hundred pesos or both, when dealing with illegal drugs or substances with similar effects that aren't included in the previous parts.
+
+Article 237.1. People sanctioned to imprisonment of three to eight years:
+
+a) Professionals who, authorized to write prescriptions or administer illegal drugs or substances with similar effects, do so for purposes other than strictly therapeutic; and
+
+b) to whom, because of the post or employment they perform, and as a consequence of infringing on the legal orders or regulations that they are obliged to, permits the introduction or trafficking into the country, or the extraction from it, of illegal drugs or substances with similar effects.
+
+2. if the planned acts in the previous section are carried out with relatively large quantities of the substances referred to, the sanction is imprisonment of four to ten years.
+
+Article 238. Whoever infringes the measures of control legally established for the production, fabrication, preparation, distribution, sale, dispatch of prescriptions, transport, storage or any other form of manipulation of illegal drugs or substances of similar effect is sanctioned with imprisonment of six months to two years, or a fine of two hundred to five hundred pesos, or both.

content/blog/2023-07-24-harvesting-onions.gmi

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+---
+title: "Harvesting onions"
+---
+
+It's been a busy few months on the allotment since I last posted. Plenty going on, but the big news is that I am now self-sufficient for onions!
+
+=> /img/harvesting-onions/onions.jpg Harvested onions
+
+This is half of the crop: 43 onions (one isn't visible). I planted some sets out in April, on a whim (I wasn't planning to grow any this year), then felt bad for the left-over sets and planted those too, a month later. Successional planting isn't actually a very good idea with onions, and that second planting is looking a bit weedy compared to this one, but I'll make the best of it.
+
+When onions are ready to harvest, the green tops start to fall over; once around half of the crop has done that, you bend over the neck of the remaining ones, pull them, and set them out in a dry, airy place to start drying out. These onions are bred for storage - if they're harvested in optimum conditions and "cured" correctly, they might last for a whole year after harvest - at which point the new crop of onions will be ready. Plant enough of them each year, and you'll never have to buy an onion again.
+
+Did I plant enough? ~100 onions is ~2/week for the whole family, which might be a bit short. I'm planning to get some more in the ground in September - onions can be overwintered, which moves the harvest from July/August to June/July, so that cuts me down to 11 months to cover. You can also pull and eat onions before they form bulbs, so hopefully that'll be enough to get us by. It's quite a feeling!
+
+## Other alliums
+
+I also started leeks from seed in May, in a temporary seed bed. These got transplanted this week, and should be ready from December.
+
+=> /img/harvesting-onions/leeks.jpg Leeks in a raised bed
+
+It turns out the allotment has a patch of wild garlic too - but by the time I noticed, harvest time was over. I'll be watching for it next year! Living in Devon when I was a kid, we used to forage for this stuff along riverbanks - the leaves are delicious, but also the flowers. They grow enclosed in a sort-of pod, and if you pick them before they flower, they're amazing - fresh, cooked, or even pickled. The seed they set is also garlicky and lovely, but mostly pickled.
+
+=> /img/harvesting-onions/ramsons.jpg Wild garlic!
+
+## Sweetcorn
+
+The most backbreaking thing I've done so far is to set up a crop of sweetcorn. I've got a big 8M² field into which I crammed ~200 seeds, back in May. I'd covered it in cardboard over winter to keep the weeds down, but I needed to dig, furrow, and then plant. And wait.
+
+And wait. And wait. Looking back, I missed every single opportunity to improve germination rates, so from the ~150 seeds, I got perhaps 35 plants. I'd gone for direct sow in the belief that 200 plants was too many to manage in seed modules, and planting them out would be a pain, which is kind-of true, but at the same time, this is my main crop and I couldn't really allow it to fail.
+
+I still had 50 seeds, so in June I got them into an emergency seed bed (the one the leeks are in now, actually). I still missed some tricks to improve germination rates (pre-soaking, for instance), but managed to get pretty much all of them to germinate, and finished transplanting them out to fill in some of the gaps in the field. So I'm still well short of what I'd hoped to grow on this field, but it is at least worthwhile. 1-3 cobs per plant mean I could stlil end up with 160 cobs of corn, which is respectable - maybe 16kg of cobs.
+
+=> /img/harvesting-onions/maize.jpg Sweetcorn field
+
+Still, I learned a lot for next year. Also, weeding this field has been an incredibly time sink. I was hand-weeding for much of it, but switched to a dutch hoe this month which has helped a bit. Still, it's a huge time sink.
+
+## The other two sisters
+
+The "three sisters" are sweetcorn, beans, and squash. I'm growing all three, but I was too much of a wimp to put them all in the same area. With the benefit of hindsight, that was a blessing this year - I've been walking all over the sweetcorn field with weeding and transplanting and would have done a lot of damage to the squash if they'd been planted together. On the other hand, it's not very space-efficient. I'll probably try co-locating them next year.
+
+Anyway, here's the squash, which has been a joy to grow. 8/10 seeds germinated and it's quite vigorous:
+
+=> /img/harvesting-onions/squash.jpg Squash in a raised bed
+=> /img/harvesting-onions/squash-closeup.jpg Close-up of developing squash
+
+I chose a "landrace" - Desert Spirit - which means the plants should show a fair bit of variety, and I do see that in their fruits. It creeps along the ground and I could see it helping to suppress weeds when interplanted with the sweetcorn.
+
+The beans have been a different story. With the help of a friend, I built them a frame and planted them out in late April, and they... yup, failed to germinate. I got four plants out of ~60 seeds. Again, the soil was too cold - I was being impatient. The seeds rotted and/or were eaten by hungry critters. The plants that did come up were devoured by other hungry critters, leaving an empty bed. Completely empty. No beans.
+
+I'd planted a borlotti variety, and I was hoping to harvest them dried for storage into winter. Fortunately, the previous allotment tenant had left behind a bunch of seeds, including some regular French runner beans, so I planted them in the emergency seed bed at the same time as the sweetcorn. The good thing about planting too early is that you have time to plant a bit late! A neighbour also came through with four extremely vigorous plants he'd grown from seed and didn't have room for. So, despite the failures, I've got a fully populated bean frame with red flowers showing up all over - I just won't be able to store them dried. They should be fine to freeze, though.
+
+=> /img/harvesting-onions/beans.jpg A bean plant climbing up a pole
+
+Also completely unexpected, but much appreciated, were six broad bean plants left on the communism table at the entrance to the allotments. i'd not thought to plant any, and had to scramble to find somewhere to put them, but they matured early and provided us with ~800g of pods over the course of this month. I should definitely plant more of them next year - I seem to have planted relatively few things for an early summer harvest this year.
+
+## Asparagus
+
+Just a quick note to say that it isn't dead after all. A week after my last post lamenting its demise, it started pushing spears up through the mulch. I didn't know when it had been introduced, and you're supposed to leave it alone for the first three years, so I decided not to harvest anything this year - but later learned from an allotment neighbour that it had been planted at least five years ago, so I missed an opportunity here. Another one for next year.
+
+Well. I did harvest *one*. And it was delicious.
+
+=> /img/harvesting-onions/asparagus.jpg One single solitary asparagus spear
+
+## Culinary fruits
+
+Rhubarb, gooseberries, blackcurrants, redcurrants, whitecurrants, strawberries, and raspberries have been popping up since June in various quantities. I got 1kg gooseberries off a single bush, and they were incredible. Of the various currants, the blackcurrants have been by far the best, but when fresh they have a taste that's taken me a bit of getting used to. It's nice, but almost wine-like - nothing like Ribena. We've had ~1.5kg of them, anyway, most of which are in the freezer. Strawberries and raspberries are still going strong - just like last year, they provide the baby with his daily fruit, with a bit left over for us from time to time.
+
+=> /img/harvesting-onions/blackcurrants.jpg A typical blackcurrant harvest
+=> /img/harvesting-onions/showing-off.jpg Currants and gooseberries and broad beans, oh my
+
+The rhubarb is incredibly prolific. I've harvested ~20kg so far this year, and it's barely made a dent on what's available - I could double that tomorrow if I wanted. I've given maybe half of it away so far, and have the rest preserved, either dried or frozen. I do want to try pickling some, and perhaps making a rhubarb syrup. However, the best thing to do with it is "Icelandic Rhubarb Bars"
+
+=> https://www.saveur.com/recipes/icelandic-rhubarb-bars/ Hjónabandssæla
+
+There's more butter in these than rhubarb, but they are absolutely delicious and definitely contibute to a happy marriage.
+
+Oh, and it turns out we have a peach tree on the allotment. I thought it was a cherry. It's only given us a single fruit though. I may replace it for next year.
+
+## Nightshades
+
+The aubergine plants I was so concerned with in my last post have survived, although I wouldn't necessarily say they've thrived. They spent a long time sat in a stunted state, with very few leaves - I think it was a mixture of them being too cold, and me over-watering and under-fertilising them. I finally relented and gave them some organic chicken manure fertiliser while reducing the watering frequency to twice-weekly, and they recovered somewhat. I've got flowers, but no fruit - exactly where I was in April.
+
+No pictures. I am somewhat disgruntled by the aubergines and probably won't try them again next year.
+
+The tomatoes, by contrast, have been a joy. They germinated copiously, and I managed to get all 30 planted into a single greenhouse (since the aubergines were taking up so much space). They're a bit crowded, but every time I go in it smells amazing, and I am getting some small fruits. There's a lot of green tomatoes in there, so I'm hopeful this will pick up through August and September and it can start to make a significant dent in my tomato buying. There's no chance of becoming self-sufficient in them, though - we get through ridiculous quantities.
+
+=> /img/harvesting-onions/tomatoes.jpg Tomatoes (and a few more gooseberries)
+
+Giving them more space might be possible next year if we skip aubergines - 16 plants per greenhouse would be much more sensible, and might let the fruits be larger. I managed to get 30kg of compost (produced from our garden waste bins) off of the local council, which has been a great soil improver for the tomato greenhouse, and I've been feeding them with an organic seweed-based liquid feed as well, but there's probably more I could do there. They've not had any chicken manure yet.
+
+The peppers have been a mixed bag. I've got a pot of chillis growing outside the house in a hanging basket, which are developing nicely enough - although the foliage is turning a funny colour. I think it needs feeding as well!
+
+=> /img/harvesting-onions/chillis.jpg Chillis
+
+Of the ~30 capsicum seeds I planted, only 5 germinated, so they have the third greenhouse to themselves. I haven't converted that one back to an earth floor yet, so they're in pots. They suffered pretty badly when we took a week's holiday at the start of July (up to Shetland to work on the house there - more on that in another post) - but have bounced back really well and we have ~20 fruits growing, somehow. Fingers remain crossed for them.
+
+=> /img/harvesting-onions/sad-pepper.jpg A sad-looking capsicum plant
+=> /img/harvesting-onions/happy-pepper.jpg Juche necromancy at its finest
+
+## Coming up
+
+I've been keeping a running count of things I've harvested; so far I'm at ~16,000kcal, which I calculate to be about 0.75% of our annual calorific demand, ignoring dog and cat (~6000kcal/day). So we've got a long way to go. About half of those calories are in the onions I harvested this week, and which prompted me to get writing again. The fruit are much more energy-dense, but the quantity is less, of course - except for the rhubarb, which is difficult to eat in huge quantities without also getting through a lot of sugar.
+
+The three sisters should provide the bulk of the calories remaining to come out of the allotment; back in January, I was hoping for 25,000kcal of sweetcorn, but I probably won't make even half that. Hitting ¼-⅓ of the family's calorie intake is probably not going to happen, but it will be interesting to see how wide of the mark we are.
+
+I already mentioned trying to overwinter onions; I've got broccoli and carrot seeds coming too. Those should provide a decent boost over autumn and into winter. You can "clamp" carrots to store them, which might be worth a try.
+
+I've not done any salad yet, so that will be a focus over autumn and into winter. I've got winter purslane seeds coming too, but I'll also try a bunch of stuff inside as the greenhouses get freed up.
+
+The allotment has a blackberry stand, which I've managed to keep in fairly good order, and the apple tree at home is looking weighed down with fruit. I'm also going to be foraging for plums a fair bit over August and September - there's a lot of trees around, but I was a bit late to it last year. I think it's reasonable to count foraged food towards the total. In that vein, I'm also on the lookout for sweet chestnut trees in the vicinity - we always used to forage them as kids. You can get a lot of calories very quickly that way, and they're absolutely delicious.
+
+=> /img/harvesting-onions/blackberries.jpg A well-pruned stand of blackberries
+
+That picture also shows off a refreshed woodchip surface around the greenhouse holding the peppers. Maintenance work, weeding, pruning, composting, watering - it's constant effort and I've not really talked about it above. Just let it be known that I'm putting an hour or so per day into this. Very inefficiently, I'm sure, but human labour will definitely be the limiting factor on a larger plot.
+
+Onwards!

content/blog/2023-08-29-straw-bales.gmi

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+---
+title: "Straw bales"
+---
+
+Part of our long-term plan is to get some land and build our own house(s) on it, in a manner that's suitable for self-sustainable living. Building houses is hard work, of course, and the modern building industry is rather problematic, so I've been looking into "alternative" methods of building for a few years.
+
+The Centre for Alternative Technology is a bit of a hub for that in the UK, and I was signed up to both their "Natural Housebuilding" short course and "Green Building" MSc pre-pandemic and pre-baby. This year, things felt stable enough for me to get back to it, so a friend and I went on their "Building with Straw Bales" course last week. Five rather intensive days of theory and practice that left me feeling quite capable of.
+
+I'll detail the main things I learned day by day, but there's a canonical book if you want a reference manual, which I shall link to here as well.
+
+=> https://cat.org.uk/ Centre for Alternative Technology
+=> http://schoolofnaturalbuilding.co.uk/barbaras-book/ Building With Straw Bales book
+
+## Prospectus
+
+Tuesday, Wednesday, and Thursday all followed the same general format:
+
+* 0800 - 0900: breakfast
+* 0900 - 1045: practical
+* 1045 - 1115: tea break
+* 1115 - 1300: practical
+* 1300 - 1400: lunch
+* 1400 - 1630: practical
+* 1630 - 1700: tea break
+* 1700 - 1800: practical
+* 1800 - 1900: dinner
+* 1900 - 2100: seminars / lectures
+
+Monday and Friday were both part-days, but add them together and you've got almost another full day. We were quite busy - the overall impression was of a course that should be twice as long or have half the content.
+
+The course has space for twelve people; we were nine this time around, as three were no-shows.
+
+### Monday
+
+Officially, the course started at 5pm on Monday afternoon with a tour of the CAT facilities, where we visited the straw bale buildings they have on site, talked about how they're put together in broad terms, and then had dinner and a couple of hours of seminar-format conversation about the course and each other.
+
+We did all that, but we actually got there Sunday evening and ended up helping the course organisers (Bee Rowan and Hassen Mzali) to set up. CAT weren't super-organised, and the course space ("the pole barn") was a mess. We swept out large quantities of old straw, uncovered the demonstration kit we were going to build on, and then started sorting the straw bales we were meant to be using for the course, which had been stored from the previous year under the barn's roof overhang.
+
+Nobody thought to check for hazards, and we ended up breaking open a wasp's nest that had set up between two of the bales, leading to a swarm of angry wasps and 20-40 stings apiece for several of us. I got off lightly with just a couple, but it wasn't the most auspicious start to the week - although it made for a reasonable bonding experience. We ended up relocating the course (and the demo kit!) to the CHP building instead.
+
+### Tuesday
+
+We spent this day getting started with the demonstration kit, which is used to demonstrate load-bearing straw bale construction. It consisted of a sole (floor / base) plate and a roof plate, with room for six bales between them. Timber uprights were fixed to the sole plate and passed through holes in the roof plate, simulating timber framing for doorways and windows, while a brace was present at each corner. These all mirror or represent actual construction details.
+
+=> /img/straw-bales/demo-kit.jpg Image of the demo kit, some straw already in place
+
+The overall process was explained to us - we build the walls using straw bales, which must be made to fit the lengths required, and placed in a running bond. Once the walls are completed, ratchet straps (5 tonne+ loading) are used to squeeze the three components together, giving a solid construction. The roof is then built, putting its load onto the roof plate (which distributes it along the walls). Sometimes the roof is sufficient to maintain compression all by itself, but you can also replace the trucker's straps with packing straps (similar loading) and leave them there permanently. Compression forces air out of the wall and makes it behave as a single unit.
+
+The first layer of bales is held in place by upward-pointing green hazelwood spikes set into the sole plate. These go about ½-⅔s of the way through the bale, and give it some resistance to being knocked out of place. Two of these per bale, and yes, the Buffy the Vampire Slayer theme tune was playing in my head throughout.
+
+The timber framing is used to keep openings square as the house shifts, and is generally useful for attaching heavy things to, since it's fixed into position. It's not load-bearing, in that it's not needed to hold the roof up, but it does take some of the load if it's there, of course.
+
+Where a timber post is present, the end of the surrounding bales must be 'notched' - a space cut out - to wrap around it. Fit everywhere should be snug, but not too tight - forcing a too-large bale into an opening will just push other bales out elsewhere. We saw this in action, popping a corner brace of entirely at one point. Friction makes getting bales into place difficult, sometimes - this can be overcome by using plastic bags to temporarily lube the gap, or by putting bales in with their mates 'corner-to-corner' and pushing two in together - either horizontally or vertically. Or you can use ratchet straps to compress horizontally, making space to slip a bale into its place in the wall before removing them again.
+
+Each bale must be checked for damp or mould and have each of its faces dressed. This means cutting away loose straw to get a flat surface (as much as possible). We used alligator saws (double reciprocating blades) for this, and also for cutting the notches. If a bale is too long or too short, we need a specific length, or if it's not dense enough, this can be fixed by modifying the bale, which we got to practice at length.
+
+Techniques for bale modification centre on the two strings holding it together. If a bale needs splitting into two smaller bales, we use baling needles to insert two new strings. These are tied off with a trucker's hitch (to get tension), and the old strings cut and removed. This can turn a single 1M bale into two 0.5M bales; or into a 0.3 and 0.7; etc.
+
+If a bale needs to be lengthened, we can cut the strings and add some straw from another bale. They generally consist of leaves of straw, so you can take slices quite easily. Extend the cut strings on the bale with a length of baling twine, then use a trucker's hitch to get tension again. Always add a centimetre or so to account for increased tension.
+
+To shorten a bale by a small amount, such that the baling needles are silly (there's no real use for bales < 25cm in length), you can do the same - cut the strings, remove some straw, re-tie. You can also use a clamp to streamline the process.
+
+We built some wall and tried out the dressing and bale modification techniques. It was slow going to start with, but things sped up after the tea break and we made some real progress.
+
+The seminar covered properties of straw bales and some history. Fire resistance, insulation, acoustics, historic buildings in the UK and elsewhere. We also talked about foundations a bit - the straw and sole plate both need to be protected from water. Car tyre foundations is one option; a plinth wall is another.
+
+### Wednesday
+
+This was a very practical day. We worked pretty much flat-out, modifying straw bales and building the walls up, until we hit five courses. Time and straw supply was somewhat against us, and the alligator saws were emitting smoke, so we left it at five bales high, rather than going the full six - the principles of compression are the same, regardless of height. You're going for ~2cm per bale.
+
+At four bales high, longer spans of wall without a timber post were reinforced by knocking long green hazel wood stakes down through the wall. These go in at an angle and take some horizontal loading. Make sure the wall is good and level before adding these! We got to work on that with the subtle application of "persuaders" - huge wooden mallets - to the wall, to push individual bales out or in. Focus on getting one side - typically the outside - level, since bales have variation and the outer surface tends to need the best weatherproofing and visual appeal.
+
+We tackled some awkward spots too - putting bales above and beneath windows, particularly. The framing around a window requires a long notch to be cut *along* the bale to receive the horizontal post(s) of the frame, which is enough of a faff that they brought along a pre-cut bale as a shortcut. In a real build, on a given storey, one does all the spaces above and below windows first, compressing them and getting the frames into place before moving onto the rest of the walls. Compression can be achieved with ratchet straps, and held in place with the horizontal parts of the framing, or a temporary horizontal member can be screwed into place and bottlejacks (or even car jacks) used to push against it and compresss the straw that way. Properly a faff, but necessary.
+
+We took a break for a talk on coppicing with Sven, to talk about where our green hazel comes from, then we went back to it and prepared the building for compression, giving the walls a final finish with a hedge trimmer, stuffing gaps with straw, and putting the trucker's straps in place. We didn't have time to actually do it, though, so left it for the following day.
+
+=> /img/straw-bales/demo-kit-complete.jpg Walls of the demo kit (almost) complete
+=> /img/straw-bales/demo-kit-straps.jpg Straps in place on the demo kit
+
+The evening was more of a personal lecture by Hassen, who walked us through his introduction to straw bale building, and the projects and people who have filled his life since. Very heartwarming.
+
+### Thursday
+
+Compression! We ratcheted the straps and watched the roof plate squash the bales down by around 10cm, took away the braces and admired our handiwork. Very good. Then we loosened it all off and took the house down.
+
+=> /img/straw-bales/compression.jpg Compression of the demo kit
+
+All done, right? Wrong. We had two more straw-bale building techniques to learn, so went back over to the pole barn (the wasps had been removed in the interim) to get started as two separate teams.
+
+Those indoors worked on the infill technique, where a timber frame is the loadbearing element and straw bales or SIPs just provide the insulation. The principles are otherwise similar to loadbearing, but there's no roof plate. Instead, the frame is built to the post-compression dimensions and a temporary metal plate, or set of plates, is stacked on top of the penultimate course of bales. Slight over-compression is achieved with ratchet straps against that plate, the final course of bales (uncompressed) is put into the gap, and then the tension released and the metal plates (very quickly, lest they get stuck) removed. The bottom courses of bales relaxing causes the top course to become compressed.
+
+=> /img/straw-bales/infill-straps.jpg Straps on the infill technique
+=> /img/straw-bales/infill-compression.jpg Compressed infill wall
+
+Us outdoors worked on a straw bale wrap instead. This is designed for retrofit - you have an existing structure and want to improve its insulation by adding straw bales, either to the outside or indoors. Space is generally at a premium in retrofit, so we stacked the bales 'on edge' (so ~350mm depth rather than ~450mm). This was all relatively simple, except achieving compression was fiddly - as it would often be in real retrofit. Rather than trucker's straps, we used packing straps directly, held against the existing wall with hooks (eyebolts would be better, we were told). Unlike in infill, the compression plate remains in place and would typically be wood - perhaps ply, although it needs careful design to avoid cold bridging.
+
+=> /img/straw-bales/wrap.jpg A section of wrap on the exterior of a building
+=> /img/straw-bales/wrap-buckle.jpg Close-up of the packing strap buckle
+
+We also had a workshop and some practical work on clay with Dieter, since clay plasters are commonly used internally in straw buildings. We were then set to work preparing various clay mixes for use the following day.
+
+The seminar was, again, more of a lecture format, this time by Alex who did the Green Building MSc the previous year and had just finished up some research on moisture levels in straw bale walls during and following a storm - basically comparing lime plaster with a vapour-permeable membrane + wood cladding. Interesting stuff, but needs further research (of course).
+
+### Friday
+
+The final day finished with lunch at 1pm, and was focused on plastering and rendering. We applied an initial layer of clay slip to the infill wall, which is generally called the 'discovery coat', and learned how to make 'rats' - twists of straw dipped in slip, used to fill any remaining gaps exposed by the discovery coat and get the surface as level as possible. Then we applied clay plaster by hand, throwing lumps of it onto the surface and feathering out the edges of each blob, before coming back over with a trowel to level the surface and 'knock it up' ready for the finish coat to be applied. Then we went outside and had a go at applying a finish coat to a "here's one we made earlier" piece of board.
+
+=> /img/straw-bales/plaster.jpg Plastering practice
+
+Oh, and we took down both kits and cleaned up after ourselves, then got everything packed away ready for next year. A quick trip to the lime kiln to see how it's made and look at some lime putty rounded off the course - we didn't get the chance to play with that ourselves.
+
+## Future projects
+
+I had the long-term future in mind when taking this course, but came up with a bunch of ideas for things I could do in the short term while on it - and feel confident I could actually pull any of these off. Here's a summary of each.
+
+### Garden boundary walls
+
+The fences between us and the neighbours on either side are flimsy wooden things held up by concreted-in wooden posts. They need renewing anyway, and I'm considering lime-rendered straw bale walls, a bit under 2M high, as a cheap and sturdy option. They'd look great and the acoustic attenuation (around 54dB for this buildup) would do a great job of muffling waist-high noises like heat pumps and babies.
+
+This project is about 12 x 6 bales, and maybe 1M³ of render, per wall. The foundation can be a small plinth wall; the really important detail is how to finish the top, which is something I'm not really clear on just yet. Here's a couple of similar projects:
+
+=> https://strawbale.com/bale-landscape-wall/
+=> https://strawbuilding.eu/strawbalewall-straw-bale-wall-in-england-2/
+
+Initial thoughts are an EPDM "hat" on top of the straw but below the render, along the length of the wall, perhaps with something approaching a weep vent to aid runoff of anything that penetrates the render.
+
+We also have the boundary at the back of the garden, which just has an unadopted road on the other side. Noise does penetrate, though - we hear their kids playing, and they hear (and make comments about) ours. Since there's already a good brick wall there, with wooden cladding panels between pillars, I'm thinking a vapour-permeable membrane between that and the straw bales, and rendering just the inside face. Again, the hat needs some attention to detail. There are also runoff pipes coming into the garden from the road behind the wall, so they'd need some reworking.
+
+### Garden room
+
+Integrated into the rear straw bale wall, located centrally, we can create a D-shaped space for not many more bales. Perhaps 4M x 3M or so - whatever we can get away with without needing planning. The foundation and roof needs some thought, but I'm very confident we can get the structure in-between up!
+
+### Garage infill
+
+We have a brick-and-block garage that's really too small for a car, and I've been thinking about converting it for a while. It's around 5.1M x 2.8M, with 2.6M to the roof trusses. Straw bales on edge on both long walls would reduce it to a ~2M space, which is probably too narrow. We could use straw bales on just the short sides, perhaps. One for more thought.
+
+### Movable walls
+
+We're not allowed permanent boundaries along the front of the house, as there's a service trench right where the wall would usually go - and there's almost no space between house and street. So I'm imagining straw bales in a wheeled tray, compressed and lime rendered, at a height of 80cm-1M. This would cut out a small amount of road noise, but allow the baby and dog to go out round the front of the house. It would also be a good practice project - we didn't get to try lime rendering on the course, just clay, and I'm sure there are relevant differences.
+
+### Allotment shenanigans
+
+My allotment already has a couple of sheds, but they're coming to the end of their lives and I have a friend with no sheds at all. Adding a simple straw bale building to each shouldn't be the end of the world, although it would need committee approval, of course.
+
+## Sourcing bales
+
+Between them, the above projects could use up 500-700 traditional "flat 8" bales (around 1 x 0.45 x 0.35M in dimensions). These typically have a density of 80-120kg/M³, and are actually starting to get a bit difficult to find - modern straw bales can be much larger, and are only suitable for moving by telehandler. There is a supplier who will send 40 at a time via palletised delivery, at a cost of around £6.25/bale all-in, but you can get them much cheaper (£1-£3) from local sources. The ideal is meeting a farmer who's interested and willing to produce bales to order. Let's see what we can rustle up!
+
+## Lime-stabilised soil
+
+As a bit of a coda, Bee isn't doing much straw bale building any more; instead, she's focusing on the use of lime-stabilised soil in foundations as an alternative to modern concrete foundations, particularly in disaster relief efforts - she's spending a lot of time in Bangladesh working on exactly this. The basic idea is to amend soil with hydraulic lime, which makes it strong enough to pop small buildings onto, and resistant to flooding, earthquakes, etc. We had a very good chat about it on Sunday evening.
+
+Lime-stabilised soil has been used in civil engineering for decades, but hasn't made its way to foundations in a big way yet. Something to watch for, and something I intend to do some experimenting with myself. There's a book, but it's not cheap - fortunately Bee had a copy with her so I got to read it in the evenings.
+
+=> https://practicalactionpublishing.com/book/2550/building-with-lime-stabilized-soil Building with lime-stabilized soil, the book

content/blog/2023-09-12-garden-room.gmi

@@ -0,0 +1,128 @@
+---
+title: "Garden Room"
+---
+
+In my last post, I talked about a straw bale course I went on, and a few projects I had in mind coming out of it. One of them was the idea of a "garden room".
+
+=> /blog/straw-bales/ Straw bales post
+
+My wife very much liked this idea, and so did I - so we've decided to make it the first thing we tackle, and figured we could get stuck in as soon as we found a source of bales. She has a few friends who are farmers, one of them knows someone who makes bales, and, well...
+
+=> /img/garden-room/bales.jpg A garage full of straw bales
+
+## Bales
+
+I got one hundred bales. It works out at about 16 cubic metres of straw (top tip - 1M³ of straw more or less equates to one linear metre of wall). not all of it fitted in the garage - I've got an overflow pile in the garden, and we had to sort and throw away / gift / recycle a whole bunch of stuff that *was* in the garage. If I can't use it, things might get a bit strained at home ^^.
+
+The bales are barley straw, very similar to what we worked with at CAT; as there, most of the bales are ~900mm long, with a few much-longer outliers. I don't have a suitable moisture meter, but they feel dry - the farmer's son said they monitor moisture when baling, and stop if it goes above 15%, and then they're stored up high and under cover, so I'm not worried by that. The strings are nice and tight, and their density is ~105kg/M³. That could be higher, but it's certainly good enough. Best of all - no wasps.
+
+=> /img/garden-room/more-bales.jpg A lot more bales
+
+If you need a source of bales in Yorkshire, do get in touch and I can share their details. I'm afraid it'd be a bit too much like posting my own home address to name them publicly. Farmer and son were both very interested in the building process and want to be kept up to date with it, as do several passers-by who stopped to gawp as a trailer full of straw bales got unloaded outside a little house in suburbia. Definitely a conversation-starter, if nothing else.
+
+## Design and materials
+
+I knew from the course that I didn't just need the bales. I also need plenty of wood, to build the baseplate and roofplate; material for foundations; roof material; lime plaster; clay plaster; etc. To work out what I need to buy, I needed a design. There's also the small matter of, uh, regulatory compliance. In England, a lot of building projects need approval from both Planning and Building Regulations. If they don't get it, an apologetic-yet-burly instrument of state force will come round and knock it down again, eventually.
+
+Fortunately, there are a series of exemptions to both planning permission (called "permitted development", or PD) and building regulations. In my case, as long as I keep the building's height (measured from the highest adjacent piece of ground to the highest point on the building) below 2.5M, ensure the floor area is under 15M², and avoid things like beds, electricity, running water, etc, then I can claim permitted development under class E that is exempt from building regulations under class 6(3).
+
+=> https://www.gov.uk/government/publications/permitted-development-rights-for-householders-technical-guidance Permitted Development
+=> https://www.legislation.gov.uk/uksi/2010/2214/schedule/2/made Building Regulations 
+
+Planning and building regs have different definitions for things like height and floor area, but that's what the intersection of the two permits in my case. Your case may well differ.
+
+This is actually quite limiting, more on the height than the floor area, but I've run into both constraints. You want at least 2M to stand up in, straw bales want to be lifted up at least 300mm off the external floor level to avoid getting wet, and you need to leave space for a roof - ideally with some sort of pitch on it. So the height gets used up quickly, both from the outside and the inside. But if you want bigger, you have to ask for permission, or resite the building, or perhaps both - not really options in my case. Time to design within the constraints.
+
+CAD is very much not my forté, but there's a package called SweetHome3D that I can just about use. It's mostly focused on interior décor, but can be used to lay out walls and get an idea of dimensions, etc. Good enough to get a rough idea, at least. So I had a quick measure of the available space in the garden and started by knocking up this:
+
+=> http://www.sweethome3d.com/ Sweet Home 3D
+=> /img/garden-room/plan-1.png Outline of a D-shaped garden room
+
+Thankfully, I revisited this a few times before making any decisions. In particular, it's very important to explicitly model the *thickness* of the bales. For a small room like this, on a constrained plot, they eat up a surprising amount of the total area. If I had a particular minimum size in mind, I could see that being quite irritating, but this is just going to be somewhere to sit and watch the outside, so almost any size could work.
+
+The garden room is replacing an area of mostly-rotten decking with a pergola over it, supporting a huge viney plant that's sort of nice, sort of annoying. The brick wall I'm building against has a northeast orientation and the back of the pergola also butts up against it; it forms a square around 2.4x2.4M. There's an apple tree at the NW corner, and a much-more-functional, independent piece of decking at the NE corner. Between the two, there's about 4.6M of usable space (so the pergola covers about half of it).
+
+After taking the straw bale thickness into account, a 4.6x2.4M (exterior) garden room with a curve in it turns out to have very, very little internal space. I reworked the D shape into a much gentler curve and wound up with around 5sqm internally. So, to do anything large, the vines have to go. I was kind of hoping the pergola footings would be useful, but they're in the wrong spot. Pushing to about 4.6x3M gets a much more reasonable footprint. Sprinkle in a few doors and windows and, ta-daaa:
+
+=> /img/garden-room/plan-2.png More reasonable outline of a garden room
+
+## Foundations
+
+Sweet Home 3D rather conveniently ignores foundations and roof, but of course, I need them before I can do anything else. Straw Works do a bunch of "standard details" that are "tried and tested", and Bee's motto is "don't reinvent the wheel" - we're steered to re-use these as much as possible.
+
+=> https://strawworks.co.uk/resources/technical-details/ Standard Details
+
+A DIY project like this would normally use something like the "rammed car tyres with suspended timber floor" detail, which avoids a lots of effort in the ground. It has a "structural box beam of relatively heavyweight timber, which I'm certain is overkill for a project of this size, but as a starting point, it's a lot easier than the plinth wall details - and they require a higher level of skill.
+
+The problem is, I ruled out car tyres - I don't really want them leaching stuff all over the garden. So I'm left with doing the plinth wall or coming up with... something else. This has involved learning some physics.
+
+The mass of the building rests on the baseplate, which rests on the foundation, which rests on the soil - which eventually sits on bedrock. Your first question is how much the building is going to weigh - and straw is not super-lightweight. 105kg per metre of wall, about 17 metres of that, so about 1.8 tonnes. Add render to the outside and plaster to the inside, a lot of wood, the roof, and (for a suspended floor) the floor and people - not to mention the foundations themselves - and I'm probably pushing 4 tonnes or so.
+
+How much force is all that? Can the soil support it, or am I going to need to excavate to bedrock? Fortunately, this one is easy to answer - once you know it. Force (in newtons) = mass (kg) * acceleration (m/s).
+
+For a building just sat doing nothing, the acceleration is the force of gravity pulling it to the centre of the earth - that's what the soil has to oppose. 4000kg * 9.8M/s = 392kN.
+
+The "bearing capacity" of different kinds of soil is publicly available. My whole garden is made ground, and quite variable, but digging below the topsoil there's a lot of clay and it's very hard, with stones mixed in, so I can happily go with 300-600kN/M². Since it's force per unit area, this is a measurement of pressure - like psi, atm, pascals, etc.
+
+=> http://environment.uwe.ac.uk/geocal/foundations/founbear.htm#BCPRESUMED BS 8004 soil bearing capacities
+
+The units give a clue as to what's next - we have to work out the area we're spreading the building's mass over - the pressure it's exerting on the soil - which comes down to foundation design. The plinth wall option runs the whole length of the building walls (~17M²) and is 450mm at the base, so its area is 7.65M² - giving us 51kN/M². Even though the building is heavy in absolute terms, the soil can more than take it.
+
+How about something plinth-y? If I imagine 17 plinths (keeping the gap between each at 1M), each with a 500x500mm cross-section, that gives me 92kN/M² - the soil I have is more than capable of managing that, although some soft clays might struggle.
+
+Car tyres are plinth-y. I could also get plinths using blocks of stone, or pillars of brick or block, or cast concrete. Lots of options, all quite expensive (either environmentally with the use of concrete, or just in terms of cash) - the plinth wall would be even more expensive.
+
+To cut a long set of developments short, I have four test piers up in the garden right now. I cut down to subsoil, placed "bags for life" - these are woven polypropylene at around 120gsm into the holes, and filled them with either pea gravel or an attempt at lime-stabilised soil (10:1 soil:hydrated lime - so around 20:1 soil:lime).
+
+=> /img/garden-room/lss.jpg Lime-stabilised soil bag for life piers
+=> https://www.iom.int/sites/g/files/tmzbdl486/files/our_work/Shelter/documents/Lime-Stabilized-Construction-A-Manual-and-Practical-%20Guide.pdf IOM practical guide to lime-stabilised construction
+
+I'm not convinced my stabilised soil will set - i did a jar test and the stuff I used was still fairly rich in organic matter, and might also be too silty. The pea gravel seems fine, though - and is very easy to level. However, for those piers, the bag is structural, and that worries me a bit. If the bag splits, the pea gravel spills everywhere and the pier is gone.
+
+What are the chances of that? There are two major considerations - forces acting on the bag, and deterioration over time. Car tyres are super-hardy, of course, and also proven by decades of use in construction. For my weedy bags, the first turns out to be easy to calculate, although it took me some puzzling at first.
+
+If you take a cylinder full of air or water and squeeze down on it, the force is transmitted, fairly equally, to the whole surface of the cylinder. If you have a cylinder of a solid and squeeze down on it, that force is transmitted straight down into the base instead - the walls don't take any of it. A bag of pea gravel turns out to be somewhere in the middle of those two extremes, and the whole thing was modelled over a century ago by someone who wanted their grain silos not to fail. "Janssen's equation" allows you to figure this out for any given material at any given depth of the cylinder, but the maths quickly got harder than I could follow easily, so I decided to just take the liquid as a worst case and calculate based on that. Call it a safety factor.
+
+=> https://iopscience.iop.org/article/10.1088/1361-6404/acb470 Janssen equation
+
+Calculating the pressure on a single pier isn't too bad - 392kN divided by 17 pillars gives us ~23kN/pillar, and the bag surface area happens to be ~1M, so we can say that's the pressure too. So what can the bag take?
+
+No idea, honestly. I cheated and converted the pressure number into something I had a better intuition for - atmospheres. It's around 0.atm of additional pressure inside the bag (so 1.2atm inside, 1atm outside). I can think about that and reason that if I blew air into the bag very hard, it wouldn't pop at that. It's around 3psi, 0.2bar, 20KPa. Another comparison - you can pressurise a 2L plastic bottle to around 6atm before it blows up. If anyone knows how to convert this intuition into a calculation, I'm all ears.
+
+Longevity, I'm umming and aa-ing over rather more. 120gsm WPP sandbags are a thing, and apparently last a couple of years out in the elements, which is not super-encouraging. In the case of lime-stabilised soil, we're treating the bags with a highly alkaline substance. Pea gravel is rounded but not perfectly smooth - it has some sharp corners. I'm stabbing holes in the bottom of the bags to aid water flow. On the other hand, I have bags that have been at the allotment all year without any sign of degradation at all - and I already have lots of these bags. I can double-bag, etc. Again, if you know how to model this, I'd love to hear it.
+
+Much better to over-design than under-design for foundations, so while I'm reasonably pleased with these piers, I'm going to try some "flexible bucket" pea-gravel filled foundations, and anything else I can find that's reasonably hardwearing. I've looked at animal feed troughs, water pipes, water tanks, bulk bags... I can't get the next stage going until I have foundations in place, so there is a bit of a rush on - I've already ordered the wood for that.
+
+## Baseplate and flooring
+
+On top of a regular plinth wall, the StrawWorks details linked above just have a simple baseplate of 4x2 C16 timber. This isn't really intended to be structural, it just forms a nice base onto which you can place the bales, add fixings, etc. In the car tyre foundation detail, it includes a big fat "structural box beam" which is intended to bear the weight of the building over the gaps between piers. It's a lot of timber, and designed for a two-storey house with suspended floors and many appliances and people.
+
+In short, it's probably overkill.
+
+I popped the details of the 2x4 timber into a random timber strength calculator with the 1M gap between piers and it seemed perfectly happy that it could hold the weight with no breakage or deflection across the span - with loads of margin to spare, too. So I'm just going to do the plinth wall baseplate on top of the piers and hope for the best. If it starts to look sketchy I can always lift it up and put a proper box beam underneath it, of course. This is on order - I've got 10x4.8M lengths coming to the house as soon as they can arrange delivery, so I'll be able to do the whole thing without any joins mid-span.
+
+If we use the 2x4 for the baseplate, then we have to use super-mini joist hangers and joists, since we only have 2" to go off, so this will probably necessitate pillars under the floor as well as around the walls. This takes some load off the exterior plinths, at least. I can't fit this until after the walls are up, since I'll need access to below the baseplate in all sorts of funky ways to do compression of the walls, etc.
+
+## Walls
+
+As I noted above, I've already got the bales and they're nice. I've also sourced hazel and sycamore fascine stakes from Leeds Coppice Workers, which is a very nice-seeming co-op. £110 for 100, ranging from 1-2" diameter, and from 0.8 - 1.3M. All sharpened at one point as well, which saves me a bit of work. I do need to chop ~10 of them down into 40x 350mm stubs to poke up out of the baseplate and impale the first course of bales, but I can get onto that anytime. The shorter remaining stakes can be used at roofplate level, while the longest ones can be used at the four-bale level.
+
+=> https://leedscoppiceworkers.co.uk/ Leeds Coppice Workers
+
+I haven't bought them yet, but trucker's straps are easy to come by. Packing straps are more difficult, at least at 4 tonnes of loading (this is the force of compression on the walls, which the packing straps are expected to hold long-term). I definitely don't want one of those snapping in my face.
+
+There's some annoying detail to work out around the brick wall - talking to the course instructors and their friendly structural engineer, I might need to leave a ventilation gap and have Tyvek membrane over the straw. It might also be worth "french dipping" that face of each straw bale in lime slip and letting it dry before placing it, to give some weather and fire resistance.
+
+On top of the wall goes the roof plate, which is built similarly to the baseplate. I'll order the stuff I need for that once I'm that far up - 2x4 is readily available.
+
+I've got a pair of doors from the old shed I knocked down which will be re-used for this project. I'd also like some circular windows - perhaps up to three, although that might be one too many. I know how to put together the framing for them, but I'll need to measure carefully and, for the windows, order carefully.
+
+Externally, we want lime render, which we won't be able to apply over the winter - so it'll be tarps or membranes until spring. Internally, a nice clay plaster.
+
+## Roof
+
+I'm just not designing this yet. Too much going on in my head already. I figure I get the walls up, build lots of redundancy into the foundations and roofplate, then put whatever I can get away with up. Cedar shingle on a reciprocating roof would be amazing, but I expect not to have the space, and I also expect not to be able to get the necessary pitch (5/12). So maybe it ends up being an EPDM membrane with some kind of timber to hide it, or asphalt shingles (they're fine with a 2/12 pitch). If I really wanted to push the boat out, I could consider a metal roof - they can do super-low, almost-completely-flat pitches, but the materials are really not cheap.
+
+The flat bale wall is protected by the brick of course, and we'll just need guttering along there , but the rest of the walls will benefit from the roof having a fair bit of overhang. Fortunately, nobody will ever see both front and back at the same time.
+
+So that's where I am today. I've got a friend coming Thursday to help move the groundworks on a bit, and perhaps build some baseplate if the wood arrives in time. I've also got another offer of help towards the end of October if we're still working on it at that point. The weather's been poor the last few days, and if this keeps up we might struggle to make progress generally, but I'm hopeful we can at least get the foundations and walls done (perhaps not as far as compression, but I'd like to think so) and protected before winter gets here properly. If we can get that far, I free up a 7x5M tarp that can be a pretend roof for the duration; surplus Tyvek can protect the walls. Let's see how we go.

content/blog/2023-10-24-2-per-cent.gmi

@@ -0,0 +1,50 @@
+---
+title: "2%"
+---
+
+Well, I'm rounding up a bit. My 2023 allotment plan was to grow around 10% of the family's calories; we're pretty much done harvesting for the year, and I have amassed ~43,000kcal over the year. That's about 22 person-days of calories - or 2% of the year's calorie requirement for the whole family. Pretty short of what I imagined was possible.
+
+Prior postings on the topic:
+
+=> /blog/allotment/ Allotment
+=> /blog/allotment-plan-2023/ Allotment Plan: 2023
+=> /blog/aubergine-madness/ Aubergine Madness
+=> /blog/harvesting-onions/ Harvesting Onions
+
+So what did I get, and why am I short? Well, here's the list:
+
+```
+| Crop        | Count | kg    | kcal |
+|-------------|-------|-------|------|
+| Aubergine   |    24 |  3.3  |  495 |
+| Broad beans |       |  0.8  |  336 |
+| Cucumber    |     6 |  2.25 |  338 |
+| Fruit       |       | 17    | 8000 |
+| Jalapenos   |    15 |  0.28 |  112 |
+| Marrow      |     3 |  5.85 |  702 |
+| Onion       |    93 | 24.2  | 9680 |
+| Pepper      |    51 |  3.5  | 1192 |
+| Rhubarb     |       | 24.5  | 5145 |
+| Runner Bean |       | 14.1  | 4359 |
+| Squash      |     8 | 10.4  | 3524 |
+| Sweetcorn   |    68 | 6.5   | 6739 |
+| Tomato      |       | 11.2  | 2007 |
+```
+
+The aubergines massively under-performed compared to expectations, as did the sweetcorn, and that's the bulk of it. I had a bunch of unexpected additions - like the onions - and the fruit did very well - but it's hard to recover from your main crops producing just 20% of their potential.
+
+The aubergines were badly affected by being planted out while it was still really too cold, fertiliser shortages, possibly being overwatered, and then being afflicted by spider mites. The sweetcorn were also planted too early, and germination was poor - I tried to recover from that by getting more in later, but come the final harvest there were a whole bunch of plants that hadn't managed to produce any ears. Around the middle of October, rats or mice found the plot and did some serious damage to the ears that were close to being ripe, as well. Lots of lessons for next year. I don't think I'll grow either of them next year.
+
+The beans were *also* planted too early and failed to germinate (bit of a pattern forming, here), but I did manage to successfully recover from that by planting runner beans later, and we've got a whole load of them sat in the freezer. I'll definitely be planting again next year.
+
+The tomatoes also did rather well, although they suffered a bit from being squashed all together in a single greenhouse - we'd benefit from having the same number of plants spread out over a larger area, I think. We didn't buy any tomatoes all summer, but we also didn't manage to preserve any for winter, so I'm back to buying them again now. It was a good 4 months though.
+
+The squash was a little disappointing - we planted 9 seeds and got 8 of them - but it was no trouble all year long, and it stores easily. Absolutely delicious as oven-roasted wedges; we'll definitely be growing those again, but perhaps a better-yielding variety, and over a larger area. 
+
+The big surprise for me was just how much vegetable matter makes up this 2% - I harvested 125kg of stuff, and much of it came in waves. The freezer has loads of sweetcorn, raspberries, blackberries, rhubarb, currants, etc, sat alongside the beans. We didn't buy soft fruit or tomatoes all summer, and we've got enough stuff frozen that we're likely to still be eating some of it come spring. At one stage I actually got tired of eating raspberries! Very much a nice problem to have, of course, but it does point to the solution not being "just grow more of the same stuff". We need to grow more different things, instead.
+
+There's some stuff still to come up in the allotment - I've got a good bed of leeks, some rather sad-looking broccoli, and carrots that may be ready for xmas. None of it will contribute substantial calories, though.
+
+I've also got some crops going in for next year now - things that can overwinter. Around 100x garlic and 500x onions are being planted right now; I'm also considering an overwinter crop of broad beans. These are all going on land that sat idle last year, but there's risk in overwintering them - they might rot if it's too wet, or fail to grow much if it's too cold. If it goes well, though, I'll have freed up the space I used to grow onions and broad beans this year, for something else next year. There's kohl rabi for an early spring vegetable, for instance.
+
+One big thing we could do to improve calories out would be to get a few chickens for eggs and meat, but we're still on the fence about that for now; you can skip the odd day with plants, but you can't really do that with animals. Overall thoug, I do feel like this year was successful, and I'm definitely motivated to get more going in 2024. There's something very wonderful about feeding yourself like this.

content/blog/2024-03-06-structural-fun.gmi

@@ -0,0 +1,151 @@
+---
+title: "Structural fun"
+---
+
+This is a followup to previous posts about straw bales and garden rooms:
+
+=> /blog/straw-bales/ Straw bales post
+=> /blog/garden-room/ Garden room post
+
+Six months on from taking the straw bale course, I've managed to make it to "first fix" stage on the garden room - which is to say, it's watertight, there is a roof, and I'm ready for internal fit out. Have a picture, in case the words are too... wordy.
+
+=> /img/structural-fun/pretty-done.jpg Looking down on one straw bale garden room from outside
+
+## Foundations
+
+In the end, I went with a plinth approach. The first priority was to get a good bearing surface, and the second was to avoid having water wick up into the organic parts of the structure. After obsessing over a range of different "raised plinth full of loose gravel" options, I realised I was losing too much time on this stage and made progress by digging a series of pits down to the clay subsoil (about 700mm deep), filling them with the gravel, lining them with geotextile membrane and standing bog-standard concrete blocks on top of the gravel.
+
+=> /img/structural-fun/clay.jpg A lump of clay from about 0.3M down
+=> /img/structural-fun/hole.jpg A completed foundation hole
+=> /img/structural-fun/founds.jpg Foundation mock-up along the back wall
+
+My first few attempts at soil investigation just didn't go deep enough - the clay layer I finally hit was rock solid by comparison, and more bearing capacity calculations confirmed I was going to be fine, weight-wise. Digging the holes was back-breaking, and my friend managed to break my shovel(!) when he came up to help. A bit of mechanical assistance in the form of a mini digger would have made short work of this job, but it wasn't available to me. Equally back-breaking was disposing of the spoil - it went into bags which went into the car and on to the local HWRS, all by hand.
+
+One downside to this approach is that the building itself isn't tied into the foundation - I strapped the whole thing to the concrete blocks, but those are just sat on top of the pea gravel. I did some wind loading calculations to reassure myself that it wasn't going to just roll off away into the sunset. It was complicated by wind *uplift* factors, as well as lateral force - the wind is effectively making the building lighter by pushing against the roof, at the same time it's pushing laterally against the wall. I don't recall the maths - the friction was not overcome when assuming a windspeed of 100 miles/hour, but it wasn't order-of-magnitude safe, so definitely worth the calculation.
+
+After digging all the holes (~2T of soil out) and filling them with pea gravel (~2T in), and levelling the piers, I put together a timber box beam from 150x50mm C16 timber. This is 450mm wide (same as the bales), sits on top of the concrete blocks, and acts to bear the weight of the wall over the piers. I used the Timber Beam Calculator to work out what depth and strength class was sufficient for the span.
+
+=> https:///www.timberbeamcalculator.co.uk Timber Beam Calculator
+
+I was planning to clad both top and bottom of the box beam, but got a bit ahead of myself and built it as a single piece - which then became too heavy to lift up by myself to clad the underside. So I only clad the top. The top cladding and the noggins should act to prevent the timbers from spreading, so it's not the end of the world, but it's a (relatively minor) weak point when it comes to insulation and could potentially give a space for critters to nest. Really not ideal, but I just couldn't face disassembling it again once it was together - those 100mm screws are hard to drive.
+
+=> /img/structural-fun/box-beam.jpg Box beam before OSB3 layer on top (3rd Oct 2023)
+
+Doing it all again, I think I'd get a mini-digger and a skip for the excavated material, cut out a whole trench (rather than just piers), fill it with pea gravel and top it with something cementitious - maybe regular concrete, maybe limecrete if budget allowed, then try the plinth wall approach. What I ended up with should be fine, but the timber wasn't much of a labour or money-saver in the end, and now I have a set of 1M wide voids to cover or fill below the box beam.
+
+## Walls
+
+Phew. This is the easy bit, right? I did a week-long course on exactly this! How hard could it be to replicate it? Really hard, as it turns out.
+
+First, I needed a baseplate - building this was only briefly covered in the course. It gives somewhere for the initial, upward-pointing set of 350mm stakes to fix to - these hold the bottom course of bales in position - and also lifts the bales a bit above the expected floor level, in case of water spills. I begrudged having this in addition to the box beam, but couldn't figure out how to do without. It's made from 100x50mm C16 (laid flat) in a ladder pattern, screwed together with 150mm screws and fixed to the box beam with 100mm screws. It was important to remember to put the strapping (6M long pieces of it, 19mm wide, at 1.2M intervals) in place before fixing the baseplate - this loops over the top of the wall and is used to hold compression - and I did. More on that later.
+
+Once the prep was done, I was able to start putting bales down. Advice was to put together a wallplate at this stage, using the baseplate as a template, but I didn't have the wood for that yet and was anxious to play with the straw, so I just noted down some measurements and left it for later. That was a mistake, but look at how distracting the straw was:
+
+=> /img/structural-fun/test-fit-bales.jpg Test fitting some bales, with strapping and baseplate visible
+=> /img/structural-fun/spike-bales.jpg Really fitting some bales along the bottom course
+
+Those along the back wall needed a coat of lime render, following the "french dip" approach. I'd bought some hydrated lime (powder); mixing it up with water and leaving it to stand for a week or so gets lime putty, and mixing *that* with sand gets lime render. It didn't have to be great, and indeed it wasn't - plenty would slide off the bale if it was handled roughly at any point after application. The longer the lime putty sits, the fattier - stickier - it gets, but I hadn't left time for that, and struggled to source small volumes of ready-mixed stuff. It seems to have worked and set hard, though, and it's mostly there for fire resistance.
+
+=> /img/structural-fun/french-dip-bale.jpg A bale, french-dipped
+
+Between the render and the wall, I also placed some vapour-permeable membrane, to protect the straw and render from rain. The wall and roof provide plenty of screening, but I figured this was worth it as defence in depth - and it would have been impossible to retro-fit. The membrane is 1M wide, so every two bales (700mm) I put a strip of it in and pulled it taut against the bales. Once tightened, the strapping helps to hold this in place, and the edges will be embedded in lime render at the corners.
+
+=> /img/structural-fun/back-wall-second-course-of-bales.jpg Second course of bales going up along the back, vapour-permeable membrane in place.
+
+I built up the north and west walls to four high first, and definitely experienced some bale frenzy in doing so. Each bale needs to be dressed and sized, then you just hoist it up and there's half a square meter of wall... done. Absolutely hypnotic. I eventually tore myself away from that for long enough to do the upright posts for the door and window, which unlocked filling in the east and south walls:
+
+=> /img/structural-fun/four-bales-high.jpg Four bales high along north and west (18th Oct 2023)
+=> /img/structural-fun/window-posts.jpg Bales tarped up, window posts installed (21st Oct 2023)
+
+These uprights are 2x50x100mm C16, nailed together to create 100x100 posts (apparently this is stronger than a single piece of wood). I cut holes into the OSB and fixed them into place with a combination of screws, nails, and blocking (extra noggins placed to constrain the wood) but they were pretty easy to flex around, so I put some temporary supports up for them until they could be supported by the rest of the wall.
+
+Up until now, I hadn't had any notches to cut, for wrapping the bale around the posts, and I was getting by dressing the bales with a hedge trimmer (although did cut through the cord once, oops). It's supposed to be possible to cut notches with a hand saw, but I wasn't having any luck, so decided to shell out on a second-hand alligator saw. It's got a tiny 350mm blade, but made cutting notches and dressing bales much easier - looking at the walls, I can still tell when I switched from one tool to the other from the quality of the dressing. I was quickly up to five or six (the target) high all around. I drove 1M long stakes down into the wall at four bales high - two stakes per bale.
+
+=> /img/structural-fun/five-bales-high-east.jpg Five bales high along the east wall, around the window posts (7th Nov 2023)
+=> /img/structural-fun/six-bales-high-south.jpg Six bales high along the south wall, around the door (10th Nov 2023)
+=> /img/structural-fun/six-bales-high-west-wallplate.jpg Six bales high on the west wall, with wallplate exposing crooked wall (11th Nov 2023)
+=> /img/structural-fun/wallplate-east-corner-off.jpg Wallplate ladder on the southeast corner showing a different kind of off (17th Nov 2023)
+
+So, yes. Bale frenzy. Once I'd gotten six high, I pulled out my baseplate measurements, built a piece of wallplate, and hoisted it onto the west wall... only to discover that it really wasn't level. It was actually very obvious that the line was wandering just by eye, but I was rushing and not paying attention to such things. Next time, I'll have a string line up, but this time I had to take the corners down, resize a bunch of bales (it was especially soul-destroying to resize a bale I'd already resized a week earlier) and get them back up - all while the weather deteriorated and hopes of getting a roof on before winter receded. I got there eventually, though, put the wallplate (100x50mm timber, upright, OSB glued and nailed onto the bottom, lots of noggins) up in sections, and screwed them together.
+
+=> /img/structural-fun/wallplate-east-corner-ok.jpg East corner again after a week of pain (23rd Nov 2023)
+=> /img/structural-fun/wallplate-up-from-south.jpg View of south wall with the wallplate on top (26th Nov 2023)
+
+Even this effort didn't make the walls perfectly level, but at least the wallplate sat on top of the bales all the way around, rather than being out in space. I found a reference in the Canadian Straw Bale Association code that suggested load-bearing straw walls shouldn't be more than a couple of inches out, and as far as I could tell I was within that, anyway, so I decided to press on with compression.
+
+I'd decided to use the in-situ strapping for this, since it was going to be very difficult to use anything else along the back wall, and if it'd work there, it'd work everywhere else too. With hindsight, this was a bad decision - I couldn't get much on the back wall as the straps would break when I tried! Examining the architectural details belatedly revealed that 29mm strapping is recommended, rather than 19mm - but the main cause of the breakage was repeated use of the tensioning tool on the straps, as I moved between them in an attempt to keep the pressure even. It has a grabby metal "foot" which digs into the strap, and that would cause a bit of damage every time it was used; disentangling the foot from the strap under tension, in particular, would just cut it. I ended up using truckers straps everywhere else and just accepting minimal tension on the back wall, which at least gave me a nice fall on the roof by default.
+
+=> /img/structural-fun/south-corner-compressed.jpg Southeast corner with strapping tensioned, mild compression (26th Nov 2023)
+
+This wasn't the end, though - the wallplate needed finishing. After getting the compression on with trucker's straps to squish the walls, tightening up the strapping to match, I needed to cut holes in the bottom of the wallplate for the 1M hazel stakes to go down through, using a hole saw - again, two stakes per bale. That done, I had to add noggins for the roof rafters to rest on top of (600mm centres, more on that shortly), then fill the wallplate with straw for insulation, *then* put the OSB lid on top. That last bit was especially important as every time it rained, water was filling the tarp-lined voids in the top of the wallplate, then slowly seeping through if I didn't bail them out. And it was raining a *lot*.
+
+I got all that done for the north section of wallplate, but didn't have time for the rest - we were going into a prolonged period of bad weather, and I had work, christmas, and a vacation in Finland to juggle - so I decided to pop some OSB sheeting on top of the unfinished wallplate to address the pooling issue temporarily, tarp it all up, and leave it for the new year.
+
+=> /img/structural-fun/north-wallplate-filling.jpg Filling the north wallplate with straw and lidding it (29th Nov 2023)
+=> /img/structural-fun/the-saga-continues.jpg The saga continues (26th Jan 2024)
+
+For various reasons this ended up being a two-month break. I'd imagined the walls were safe beneath the tarps, but over this period some water did get into the north and west walls - due to how I'd put the compression on (a single trucker's strap with the buckle on the inside of the wall), the top of the wallplate was angled inwards and water was running constantly down the surface of the tarps, soaking through in some places. I ended up having to dig out rotten straw to a ⅓rd depth in several patches. Fortunately, it's not critical - the voids can become niches and shelves - but it's definitely not ideal. That's the price of not getting the roof on in time, I guess.
+
+I also had to revisit the compression - I'd actually compressed *too much* along the south wall, and the tilt introduced by the uneven compression meant the roof rafters would mostly be out of touch with the wallplate. I ended up cutting the straps there so I could finish the bottom of the wallplate along the door opening, and the whole thing *relaxed* and straightened in front of my eyes.
+
+=> /img/structural-fun/clad-south-bottom-wallplate.jpg Cladding the bottom of the south wallplate in OSB (27th Jan 2024)
+
+No pics of it, but previously, the lintel above the door was intruding perhaps 20mm into the void formed by the wallplate, meaning I couldn't clad the underside. Great fun.
+
+With that sorted, it was time to complete the wallplate along all three sides, including fixing the upright posts into place with noggins and cutting them to length, then going through the hole - stake - insulate - close procedure.
+
+=> /img/structural-fun/wallplate-south-glue-and-nail.jpg Getting ready to glue and nail the lid of the south wallplate (28th Jan 2024)
+
+With that done, finally, I was ready to put the roof onto the wallplate. 
+
+## Roof
+
+When I got started on the foundations, I had no idea what kind of roof I'd have space for. Permitted development gives me 2.5M to work with, but how much of that the walls were going to take up, and where I needed to measure from, was unclear. A vaulted hip roof would minimise wind uplift forces, and give me more head height internally, so I was aiming for that... but the lack of compression along the north wall, coupled with a decision to be conservative about planning law interpretation, meant that wasn't an option. Instead, I decided to go for a regular flat roof, to minimise height.
+
+The buildup is pretty simple - Timber Beam Calculator told me that 200x50mm C24 rafters were enough to span the distance at 600mm centres, while also being strong enough to convert the flat roof into a green roof if I decided to. 18mm thick T&G OSB3 on top of that, and a single-ply EPDM membrane stuck onto the OSB for waterproofing.
+
+I'd decided I needed to get it done fast, so stuck with standard timber sizes as much as possible for the joists and edge pieces - 3.6M and 4.8M. I wanted a bit more overhang on the east and west than the 4.8M gave me (600mm of overhang in the end), which required me to extend the north and south (4.8M) pieces a bit, but nothing time-consuming - I just sistered the timber behind the join. I'd also helped out future me by marking the noggins I'd put down in November, so I knew where the joists had to go. I laid it all out, used a string line to get things square (I'd learned my lesson!), put some screws in to fix the joists to the wallplate, then added joist hangers for a really secure fixing - wind uplift really has me paranoid.
+
+=> /img/structural-fun/roof-joists-from-above.jpg Viewing the roof joists from above
+=> /img/structural-fun/roof-joists-from-below.jpg Viewing the roof joists from below
+=> /img/structural-fun/front-roof-joist-piece.jpg The edge piece along the south face of the joists
+=> /img/structural-fun/back-roof-joist-piece.jpg The edge piece along the north face of the joists
+=> /img/structural-fun/osb-roofing.jpg Installing the T&G OSB3 sheets in twilight
+=> /img/structural-fun/inside.jpg Inside after the roof was installed
+=> /img/structural-fun/ohayou.jpg South outside after the roof was installed, but before EPDM was fixed
+
+I got all this done in a single day - 28th Jan 2024. It was very intense, and the T&G wasn't properly fixed down or at all watertight, but I was determined not to suffer any more water damage. It's also the day I got my worst build-related injury (so far, at least).
+
+The way you get the front and back pieces on when you're working by yourself is to attach a piece of wood to the bottom of the end joist to act as a ledge. You can then rest the 4.8M piece on that at one side, while screwing in the other, then go to the other side of the roof, screw that in, and remove the ledge. I'd done all that with no issues on the south, but was struggling to fit the ledge on the north - I was using a short piece of 2x4 as the ledge, screwing it into the underside of the joist with the drill. Rather than the screw spinning, the 2x4 was, and to stop it from doing that I braced it against the side of my head. Stood on a ladder, obviously. The screw wasn't driving in cleanly, so I decided to put the drill into reverse to bring it out so I could try again... but didn't adjust my bracing first, so the 2x4 spun in the opposite direction and cracked me one on the right temple.
+
+No concussion, and I didn't fall off the ladder, but I did turn the air blue, get tinnitus in the left ear for a week, and grow an impressive bump on the template. After a few hours of rest I was able to carry on, but it was a very strong reminder that building sites are dangerous places and you need to step back and think if you're having a problem with something.
+
+A couple of days later the EPDM membrane arrived, and I was able to get it onto the roof to make it fully watertight. A day of struggling with the T&G to get it sited correctly and screwed down, then a day to glue the EPDM to the OSB and attach the roof trims, led to the picture we saw at the start of this post:
+
+=> /img/structural-fun/pretty-done.jpg Looking down on one straw bale garden room from outside
+
+I've since attached a gutter along the south edge (the other three edges have upstands) and the water is being directed to the apple tree in the northwest. Eventually I'll have a rainwater collection system, but I want to be done-done first.
+
+## Next steps
+
+Honestly, it's close now.
+
+I've got some more wall straightening to do, and in particular, there's one bale on the west wall that I need to shorten in-situ. I'm pretty confident that I can just cut the strings, pull off the overhanging bit, and re-tie the strings, but I've not done it yet so it could be much harder than that. I'll get a clamp on before I cut the strings, just in case...
+
+The walls are currently protected by the roof overhang, with tarps hung externally beneath that. Before the tarps can go, I need to render the walls with lime render. This will be a bunch of work by itself, and needs me to install the windows, re-seat the doors, trim the walls, go around and stuff all the gaps between bales, fix render stops to the appropriate places, and probably a thousand other things I've forgotten. I've also decided to use lime render internally, as well as externally, to improve the shear resistance of the walls (much of the resistance to lateral forces comes from the render, not the bales + compression, and I'm still a bit nervous about wind). This can't happen until the weather has improved though - April or May - and I need a ceiling and floor internally to render *to*, if I want a tidy job of it inside.
+
+The ceiling and floor are part of "first fix", along with a bunch more stuff that will turn it into a habitable space, bringing in services, etc. I've ordered almost everything I need, and it's coming this week - principally insulation for roof and floor (rockwool, which cost as much as the straw bales making up all four walls!), but also a great deal of wood (matchboard for the ceiling and underside of the roof outside; more joists for the suspended timber floor; battens for miscellaneous purposes). All that implies a bunch of awkward work, but at least I'll be dry when doing it. My current plan is to do the ceiling - 150mm depth of rockwool, with 50mm beneath the joists if I can, to maxmise acoustic insulation. I can then put the floor in, with the joists in hangers (my life would be so much easier if I'd installed these back in September, but I'll manage). I've still got old decking boards to use as floorboards; it'll be interesting to see if they're usable, or if I'll need to order *yet more wood*.
+
+I've got to fit the windows - I'm planning for a 440mm HDPE "bubble window" on the west side, looking out onto the apple tree, and I've got 1.2M of casement windows to fit on the east side, from a local second-hand shop. Both require precision, so I've been putting them off. The casement window is getting a window box attached to the uprights, while the bubble window - being lightweight and very well-sheltered - is going to be attached to a thin piece of ply, which will itself be attached to some battens running between floor and wallplate, nestled into the straw.
+
+The doors used to open and close cleanly, but I managed to knock the uprights for them a little off true when I fixed them to the wallplate. It's not much, but there's a bunch of futzing I need to do to sort that out - and I'd quite like it to be done before the lime render goes on, just in case I have to change plans there.
+
+I've also got to sort out the voids between ground level and foundation, and generally rodent- and pest-proof the whole thing. If a wasp colony decides to take up residence, I will be very disgruntled. No evidence of mice so far, but the cat did take out a pigeon that was sheltering there yesterday.
+
+Do I want a green roof? I'm still undecided about that. The EPDM isn't offensive to look at, but it's also not lovely, and it's quite a large expanse to stare at when I'm working from the home office. I think I'm leaning in the "no" direction, but only because I'd prefer it to be done. I can always come back to this another day/month/year, after all.
+
+I'd pretty much trashed the garden while working on this. It's mostly tidied up again now - and is no longer a no-go area for the rest of the family - but the lawn is a mess. I'm trying to re-seed it, but if that fails, I'll have a turfing project to do.
+
+Finally, there's decoration and furniture. Once it's dried, the lime render will receive either limewash or silicate paint and there's a bunch of neatening work to do around the edges (literally). The eventual plan is to use this as an educational space for our kid - we're planning to homeschool, assuming he's amenable once that age comes around, and it feels like having a completely separate building for that would be helpful. Hopefully it won't take me another six months to get the rest done.
+
+Ideally, I'd get the chance to do this all over again with the lessons I've learned, but I'd need to find a paying client to make that happen - I've literally no space to put another one. Do get in touch if you're vaguely in the area and might be interested!

content/blog/2024-05-19-floors-and-ceilings.gmi

@@ -0,0 +1,78 @@
+---
+title: "Floors and ceilings"
+---
+
+Work on the garden room continues. Since my last post, the floot and ceiling have been completed, and I've ordered the lime for the walls. Let's take a look.
+
+## Ceiling
+
+I tackled this first, which in retrospect was a mistake - since the floor is suspended, it would have involved less teetering on ladders if I'd done that first! Oh well.
+
+The overall buildup is a "cold roof", with the EPDM and OSB3 underlay separated from the insulation by a 50mm air gap. This is ventilated - the wind comes in at the eaves and blows along the rafters, from front to back, helping to dry out any condensation. Below that, I put 100mm of rockwool - taking me to level with the underside of the joists - held in place with 25x50mm battens, running along at 400mm centres. Covering all that, I put another 50mm of rockwool, and fixed it in place with resilient bars (for acoustic insulation) running crosswise to the battens, again at 400mm centres. Finally, I fixed some pine matchboard (tongue & groove, 12.5mm thickness) to the resilient bars. Phew. Some pics - 
+
+=> /img/floors-and-ceilings/buildup.png Early attempt to model the buildup
+
+=> /img/floors-and-ceilings/rockwool-one.jpg First layer of rockwool, held up by battens
+
+=> /img/floors-and-ceilings/rockwool-two.jpg Second layer of rockwool, held up by resilient bars
+
+=> /img/floors-and-ceilings/matchboard-one.jpg Getting started with the matchboard for the ceiling
+
+=> /img/floors-and-ceilings/matchboard-two.jpg Finished ceiling
+
+Nothing's ever quite that simple, of course.
+
+Before I started, I decided to cover the inside face of the roofplate with "wood fibre board", as that's an airtightness detail. I ended up using cut-up loft boards, which are particle, rather than fibre, but they're *probably* fine for indoors.
+
+Since the rockwool was 600mm wide, I had to cut every piece going between the joists (400mm) to size. I was going for a fairly tight fit, again to help with airtightness, and achieved that - but it meant the pieces would often end up being higher than the bottom of the joists, so eating into the 50mm air gap. I spent a fair bit of time with bits of batten, poking at the rockwool from the external access to the cavity, to get it working.
+
+I'd not thought about supporting the edges of the battens that held up the first layer of rockwool; in the end I got a bunch of little metal angle brackets and used those. Awkward, though.
+
+The second layer of rockwool was 50mm going into a ~40mm space, so had to be compressed a bit, especially under the battens where the available space dropped to 15mm or so. That compromises the insulation value some, and was also fiddlier than expected.
+
+The matchboard was prone to splitting at the edges, getting the tongue & groove mated was a pain, and I had some finicky cuts to make at the front of the garden room. Lovely stuff though and it completely changed the way the room smells the moment it was in place.
+
+Even with all those issues sorted out, it was still a royal pain to get all the parts up and fixed. It would have been easier to put the battens in place then drop the insulation down from above, for instance. Got there in the end though, and it looks alright.
+
+I still need to put something up to hide the expansion gap between ceiling and wall; coving or something. I'll seal the void with something airtight and flexible, like butyl tape, before that goes up, and for simplicitly I'll be rendering to be flush with whatever depth it ends up being.
+
+## Floor
+
+The main issue with the floor was the joists - I was using a mix of C24 6x2, and C16 8x2, due to an ordering mix-up. They were attached to the box beam with joist hangers, and I was careful enough with their placement to get a surface that's within 0.1° of level, so that worked out well enough. However, the ground level was quite uneven and I needed to dig trenches to make room for several of them. My new SDS drill was very helpful for that!
+
+Once the joists were down, we friction fitted 150mm rockwool between the joists, then put (new) floorboards down on top of that. Much simpler than the ceiling buildup. I was originally planning to use some old decking boards that I'd saved from ripping it out last year, but in the end I wanted a better finish, a continuous wood surface (3.6M long boards) and a tongue&groove between boards for airtightness.
+
+More pics - 
+
+=> /img/floors-and-ceilings/floor-one.jpg Joists in
+
+=> /img/floors-and-ceilings/floor-two.jpg Rockwool in
+
+=> /img/floors-and-ceilings/floor-three.jpg Boards going down
+
+=> /img/floors-and-ceilings/floor-four.jpg ~fin
+
+This ended up being much easier than the ceiling, and I'm much happier with the finish. Even the cuts for the front of the room are better, and everything is fixed down with hidden "tongue tight" screws, so it ends up being a continuous wooden surface.
+
+I'm debating removing the OSB at the door threshold and continuing the floorboards out; it would look better, but would also make them structural, so I'm unsure just now. There's a little gap to fill if I don't, which will be a pain to cut - but possible.
+
+As with the ceiling, also left to do is some skirting along the floor, covering the expansion gap. More butyl tape, and again, the plaster will end up being flush with it, so I'll render whatever the plane between skirting and coving ends up being, most likely. I'll be surprised if it's exactly vertical!
+
+## Tung oil
+
+The wood surfaces for floor and ceiling are untreated right now, and the floor at least definitely needs protection from traffic. I did a bit of research and decided "pure tung oil" was the way to go - this is a "drying" oil that polymerises on contact with air to form a hard, matte finish on the wood. In the pure form, i.e., with no thinners added, it's completely food-safe (although not very tasty) and doesn't emit anything nasty when it's drying or afterwards. Application is labour-intensive, though - you need several very thin coats, with at least a day between each. So far I've just practiced on a couple of offcuts, but it seems fine.
+
+I'll be getting on with the ceiling shortly; the floor will wait until after rendering is complete, as the finish will be ruined by that process otherwise.
+
+## Next
+
+Now it has a floor, we're already using it - but there's plenty more to do. I need to fit the windows, re-fit the doors (they're about 2° off level right now), and get the walls ready for rendering. Inside, that involves a lot of stuffing of gaps, trimming of surfaces, and digging out straw for niches, shelves, etc. Particularly around the southwest corner, there are some pretty large voids where bales don't meet properly - it's the corner where I learned how to do the 105° angle, and could be much better. 
+
+Outside, it's mostly about getting a level surface by trimming away excess straw. In particular, I've got a few bales that stick out significantly past the line of the wall - I just need to be brave and cut away the excess, then re-tie the bale strings. I'm hopeful the compression on the wall will keep most of each bale in place as I do this, but who knows? I've never done it before. Exciting!
+
+Once the walls are prepped, I can actually do the rendering - 22M² indoors, and about the same outdoors (since the back wall doesn't need rendering outside). I phoned up the Lincolnshire Lime folk and had a very good chat; on the strength of that, I've got 500kg of St Astier NHL 3.5 being delivered next week, as 20x 25kg bags. It's a little stronger than is generally used for indoors, but should be fine, and it's a simplification to do inside and outside identically.
+
+=> https://www.lincolnshirelime.co.uk
+=> https://www.stastier.co.uk/lime/lc-pure-nhl-3-5/
+
+Cheap, and hopefully fairly foolproof - being hydraulic gives it a chemical set so the chances of it failing are much reduced. It needs less aftercare than a render based on regular lime putty, and makes for a much more durable surface. I've never done it before - only messed around with some clay plaster on the course - so I'll be learning on the job. Fortunately, I've got one external wall that's mostly out of sight to start on...