fatgus

You’re right to be cautious, but bear in mind that not all polyurethane systems are equal. The one we’re using in this instance is water based, zero-VOC, no isocyanates… It’s very different to the polyurethane foams used in furniture or in 2k construction adhesives/foams. There are many resin systems I would never use in my house but this isn’t one of them I have zero concerns. I believe the VOCs given off by natural wood are typically those that give wood its distinctive smell, like the terpenes (I think!?) released by cedar. Not the same as isocyanates, toluene, acetaldehyde and the other crap that gases off from all manner of man-made materials. It’s weird though, how some dreadful VOCs are overlooked or even kind of desirable…. New car smell? Toluene, benzene, styrene, acetaldehyde… just part of a long list, all slowing killing you 🤷🏻‍♂️

We’ll see how the trials go Some resins are pretty grim and I wouldn’t entertain using them in the house, but for this we’re using a solvent-free polyurethane 👍

It is a small consideration Gus (we’d be daft if it wasn’t), but we’re building for us and if I’m not confident in the floor, it won’t go in. The finish shouldn’t be too dissimilar to power floated concrete, but it will ‘feel’ nicer underfoot. Most people probably won’t notice.

That’s a very good point. Who knows what the future holds? 🤷🏻‍♂️

👍👍👍

I knew nothing about it until quite recently! Worms would be an interesting addition...

We did the same and you're absolutely right, it probably makes sense to put the pipes in regardless as a backup... we'll only get the one chance to do it.

That would make me popular I can see why that would make sense, but with the system we're using the heat would be problematic during the cure.

Or stupid I love the aesthetic and feel of earthen floors. Our site is predominantly clay and we'll be excavating a fair few tonnes. It will mostly be distributed around a field, but the possibility of actually using some in the house seems to good to miss There have certainly been a few raised eyebrows when it's been mentioned. Thankfully my wife is wonderfully understanding and will entertain these ideas. She also knows that unless we arrive at a robust solution it won't be going in the house. One of the downsides of a traditional earthen floor is the curing time, so we're essentially eliminating the linseed oil and replacing it with a much faster alternative. It's not rocket science, we design resin systems daily and have access to some useful test equipment (abrasion, tensile, impact, UV exposure). There's very little worth watching on telly, so it's a good way to spend an evening

Thanks @SteamyTea 👍👍👍

It's not strictly an earthen floor. It's a kind of hybrid we're working on ourselves to allow us to use some of our excavated clay in the floor, which seems like a cool thing to do. First trial was great. Second was a shocker. We're now on six and it's getting there. What one might call a bit of a punt! Would certainly be easier and cheaper to go for the originally planned concrete, but where's the fun in that? 😁

I did say passive-ish We have no interest in certification, but I think we have a reasonable understanding of what passive actually means. Anyone who thinks it's "just a little better than building regs" has clearly done no research. It doesn't seem particularly hard to get close to passive performance just by adopting the appropriate philosophy and being diligent. This is one of the reasons for looking at A2A. A typical A2W/UFH setup is probably going to lead to a house with relatively consistent temperatures throughout. Fine if that's what you want, but there's no opportunity to quickly change the temperature in any given room. A2A seems to offer very good control of individual rooms or zones, even if MVHR does perhaps reduce the effectiveness a little. We never entertained using MVHR for heating/cooling, largely because the consensus here seems to be that it's a pointless exercise. That said, duct size for A2A is an important consideration, particularly as we would probably use oversize ducting to reduce the air velocity, but we'll have plenty of void space above false ceilings so it shouldn't be an issue. Condensation is definitely a consideration. I imagine it's something installers frequently have to deal with, so if we do decide to go for A2A we'll look at how best to deal with it 👍 That's interesting... thanks. We haven't got too far down the A2A rabbit hole yet, but dry air is a concern.... plants & eyes!

We won't have much direct slab-heating solar gain as most of our large windows are NE facing. The larger SW & NW facing windows are on the first floor with no line-of-sight to the ground floor slab. At first, we were looking at just keeping the house at a relatively constant temperature year-round, but we're now think more of actual air-con. Our neighbour has a portable unit that they were running in their kitchen/living area a few weeks ago. The outside temperature was bordering on uncomfortable, but inside it was lovely. We need to verify our heat loss calcs, but it would appear our space heating requirements will be low and some rooms could actually be heated by the equipment running in them, which is pretty mad Dry air is perhaps a concern as we'll have a lot of house plants...

The original house on our site was a 1960s self build and has some curious cast iron grates near a patio door. I found some old architectural drawings of the house and it seems as though there was a plan to use forced air heating Either it did’t work or it was never fully implemented as they have a combination of storage heaters downstairs and wet rads upstairs… a most bizarre setup!

We weren’t going to bother with PHPP modelling, but it seems that it might be a good idea to better understand the probability of overheating. Most of our windows are on the NE elevation, but we have a couple of large windows facing SW and NW. The original plan was UFH and an ASHP with cooling, but A2A seems like an interesting alternative. Does it matter if only the air is cooled, not the slab?