Nick Thomas

Both voltage and current vary, although I only knew this from watching them go, not from electrical principles. https://electricalacademia.com/renewable-energy/photovoltaic-pv-cell-working-characteristics/ goes into gory, gory detail, but i'm going to need to read it several times before I understand it ^^. Your inverter will have a maximum it can accept per MPPT anyway, and you light find 16x320W panels is close to, or at, the limit. Check its docs.

MKM were about as overpriced for OSB when I was buying. Fine for aggregates, but bad for any and all wood. Definitely pays to shop around.

The LoftZONE legs are fine, but expensive - and still not particularly stable. I installed them so the solar people wouldn't be messing around standing on the rafters, but they were quite critical of how it moved underfoot The installer was a big guy carrying a big battery through ^^

Downpipe installed. Not quite how I imagined it, but functional ^^

Reading the datasheet makes me think it's basically battery acid? Acid accelerates weathering, so it'll make the wood silver faster, which will make it last a bit longer, I guess. Safety-wise, probably fine after it dries, very nasty while wet? I found https://www.celticsustainables.co.uk/blog/silvery-wooden-cladding-fast/ which has some pics but no word on what happens if you press your face up against a treated section ^^.

Amtico publish thermal resistance (R values) in these technical documents: https://www.amtico.com/commercial/technical/ 1/R = U, so U=59ish for the Amtico Access. I wouldn't lose any sleep.

How's the fake peregrine falcon going, @Adsibob? The pigeons here are still nesting under the solar panels and it's driving me a bit mad. They lay eggs, the eggs roll straight off the roof and I get yolk or fetus all over the front of the house. And then there's the droppings. Siiiigh. I got a mini drone (<250g) and have been flying that up when I see pigeons to scare them off, which has seen mixed results so far. It does make them leave, but doesn't seem to stop them from coming back again. A touch off the original topic, but I was thinking about hiring a scissor lift for a weekend and DIY-fitting something like https://www.birdspikesonline.co.uk/Bird-Spikes/Defender-Bird-Solar-Panel-Spike to the perimeter (the panels themselves are apparently not suitable for fitting wire mesh to directly). These just attach with silicone adhesive, but I have a few doubts about their longevity, and with the eaves at 6M high, it's a slightly scary proposition ^^. Better ideas appreciated.

Something I was wondering the other day - when you contract someone to do work, does / should that contract include a schedule of acceptable tolerances?

Managed to injure myself down at the allotment, so a bit delayed on the plastering indoors. Just finished now; it took 3 bags of lime and all the sand I had left. Phew. Now for a week of checking it several times a day for cracking. Once it's had some time to cure, it'll get painted. I'm thinking whiteish silicate paint outside and earthborn "claypaint" inside - they have an offensively yellow shade which is reminiscent of the straw. Dunno if either will hide hairline cracks, or if I'll need to do something about any that show up first. I still need to get doors on the unit, shelves in, oil all the wood and fit the services too, but that's everything that could be called construction finished. Thanks everyone who made suggestions, checked my maths, or just offered encouragement. It's been a great help throughout!

Hah, just had another look at the screwfix one. The website says 100L mix capacity, but the sticker on the machine says 90L, i.e. same as the belle. Now i'm done with it, I could probably return it for a refund on the basis of false advertising :3.

My *god* that's cheap

Prices have dropped off a cliff recently. The VAT zero-rating was passed on too, which is nice to see. You can get 9.4kWh for £3650, or double that for £5595 - list price, including the inverter. Things are nicer if you can assign the inverter to the solar PV payback period instead - £2200 for a 9.4kWh battery, £4200 for double that. ( https://homeenergygroup.co.uk/lux-ac-battery-storage-hanchu-ess-9-4kw/ ) I've got a measly 3.2kWh battery at older prices and it was marginal as to whether it would pay itself back within its lifetime, but these days it's better-looking. And it all helps to cut down on the amount of gas burnt, of course.

The screwfix one has slightly larger "official" capacity than the belle minimix 150 (100L mix vs 90L mix; 134L drum vs 130L drum). It's definitely full-full at that point though. No idea how it'd look if you had them running side by side.

I've got a screwfix one in the garden right now. Obviously, I'm not a pro, but it's... working. I've put 24x100L(ish) loads through it so far. Mixes fine, no real issues keeping it clean or getting the muck out of it. It has managed to topple over backwards a couple of times, but I reckon that was user error. Working on my own, I'd tip it forwards, then go round the front to fiddle with the muck inside the barrow. It would then un-tip itself and the momentum would take it over. So, uh, don't do that, I guess ^^. No idea if it happens with more expensive mixers too. As for petrol vs electric: I am currently raging at a two-stroke brushcutter that refuses to start. So done with combustion engines.

Yeah, OK. That looks decent enough to me. It'll scrub up nicely. The drainpipe is temporary, eventually it'll come in under the overhang via 92.5' elbows and run down close to the wall.

Got there in the end. A break from rendering to let the hands heal from lime burns (d'oh) is in order before the final coat inside. Plenty of other stuff to do though. It's going to be great to take the hessian down in a week or so, although I've got one awkward set of neighbours who have already telegraphed that they're going to hate it (and hate everything already done; and hate that I replaced a rotten pergola with a huge viney beast straddling it with a modest building). They've been out measuring, bless 'em, but it's definitely <2.5M. Fortunately, the other neighbours range from indifferent to fascinated. I offered some evergreen screening as an option to block their view of the side a while back; trying to work out what's most cost-effective (and would be happy in pots) there. 2.5M tall trees, even bamboo, doesn't come cheap 😬

This is actually working \o/ (Right hand side is rubbed up, left hand side is not). Managed to get two bags on in one day yesterday, right the way up to the door at the front. The finer sand really aids workability, although it's not *great* stuff, there are some big pebbles in it, and a little bit of sharp glass. Found some charcoal as well? Still, 3 more long days of this and I should be finished. A few hairline cracks have shown up, especially in the very first section, where I think I put it on a bit thick. So far they've all rubbed out without issue. Limewash apparently helps to heal them as well, once it's time for that. Or I can always cut bits out and re-do, but hopefully it won't come to that. Still not level, obviously.

I'm just guessing, but perhaps the maximum size of aggregate in the plaster? A 3mm gap won't let 4mm particles through, but a 6mm gap will.

Would downgrading to direct electric impact the EPC significantly? Would be fun if it took it below the legal-to-rent threshold, although I think you can coast on the current one until it expires. Bit of a loophole, that.

The description reminded me of a grand designs - https://www.granddesigns.tv/southherefordshire . Particularly the portal frame. Perhaps the suppliers list will be of use? The episode was quite into the portal frames too, watching it might give you some ideas there. Perhaps cut the OSB into V shapes, so there's no joints at the top? I vaguely recall that's what they did.

Eyy, that's £520/sqm.

I've kept a spreadsheet ^^. Ignoring tools, the unit, services, things I bought but never used, and factoring in what I'll need for the finish coat, I'm at about £4500, making the straw less than 10% of the total build cost. Other big-ticket categories - about a quarter was wood: OSB, 2x4, 2x6, 2x8, floorboards, ceiling cladding, that kind of thing. I was buying a lot of that piecemeal, due to limited storage, so I also paid a fair bit out for delivery, and used what I had fairly inefficiently. Could probably get this down a fair bit with better planning. I already had the doors, but spent ~£500 on windows-that-got-used. Honestly, I'm not very happy with the doors, but won't think about a replacement until after everything else is done. Might be another £1000-2000 if I went for something with a big double-glazed panel on the side - it's a ~1.3M wide gap that needs filling. It's taken a long time, but I've not actually put a huge number of labour hours into it. I've not tracked that closely, but the rendering has been ~20x6hr sessions so far, for instance. At £25/hr that'd be a nominal £3K. Doing load-bearing straw like this swaps out a lot of technological wizardry in favour of brute-force labour like that ^^. If I were to do it again, especially at a larger scale, I'd probably be thinking about straw SIP stuff instead, and it seems like the direction of travel is generally that way. I found https://www.thelaststraw.org/panel-fever/ a very interesting read on that front.

Honestly I'm a bit of a health & safety nightmare at the best of times. But yeah, after that I got a little step-up for the inside and will be getting a big one for the outside. I've got some lovely work boots, I'm just stupid enough to wear slippers instead sometimes 🙄. Second coat is finished now, aside from a couple of spots where there were really deep voids to fill - I decided not to try to turn them into niches, in favour of just filling them up with copious amounts of straw-lime. I probably need one more bag of NHL3.5 to finish the voids off, then enough NHL2 to do the finish coat with fine plastering sand over the lot. Calculators suggest that could be another 400-800kg of render at 2.5:1 - another 9 bags of lime in the worst case (~10mm thick), 5 if I go for 6mm thick. I think I'd have ended up using significantly less lime if I'd gone the stipple coat route, but, oh well. Some of the void filling has been ridiculous as well ^^. I still need to fit the services, and of course, I've made life difficult for myself there by plastering the unit in. I figure I can cut a series of portholes for access and make them reopenable though. Something to do while taking a breather and collecting the materials for the final coat. I feel like I'm getting better at plastering, but it'll be interesting to see if I can manage a decent level of finish for this final coat. Top rule has to be "don't stop halfway through an elevation" ^^. I looked into buying premixed bags of lime topcoat to control consumption a bit better, but first impression is that it's wildly overpriced.

Back in action. Finished the second coat outside, and got started on the inside today. Three bags of lime left, but I'm out of sand. I can either get as much as I need in 25kg bags for ~£50, or get another whole bulk bag for ~£60. I'm very slightly short of all sorts of things right now, which is a bit of a pain. I did clean the lime off the bubble window ^^.

One place left on https://cat.org.uk/events/build-a-tiny-house-test-august-2024/