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

@@ -5,7 +5,6 @@ title: "Nick Thomas"
 ## Meta
 
 * mailto:me@ur.gs
-* xmpp:me@ur.gs
 * Alias: lupine
 * Alias: CommunistWolf
 

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...

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