mistake_not

@SpinnyDid you resolve this? Excuse my stupidity but was the actual door system ok and just had install? Or system flawed. Reason for asking as we are planning on an eclipse door system, but now may change our mind...

But - our house is 1980 and we were sure the only asbestos was the artrex

We had it in our ground floor. Did a quick test by using a kit from https://www.asbestos-sampling.com/?srsltid=AfmBOoqDhxnHe7r9cDAYl9R1ZU-pZXzvw4H_uEjrNZ7Wa6WZeCDXLN47 whilst in full suit / face Welly. Came back as lowest grade. Was removed under non licenced notifiable work in a 2 day period across the entire ground floor a few weeks ago (which was empty at the time). Didn't need negative pressure etc, but lost of sheeting etc. Got air testing after (not a requirement for this work) but wanted for peace of mind.

Don't see why not. It's what I'm planning on doing.

Not a solution but read this thread of the consequences and remedial action: I suppose options are: 1. Rip down bricks, replace the PIR with cavity bats / pump in eps. 2. Pump in eps from the outside 3. Pump in a closed cell foam. 4. Give up, do IWI / EWI and an airtightness barrier. 2 is probably easiest and cheapest. Depends on if you have enough residual cavity for the beads to properly flow.

In my renovation I have ripped off the window sill around my bay window and exposed the cavity underneath. It's had some failing glass foam insulation in it, so have emptied it all out. For context the wall is a traditional brick and block build, with the window sat on the outer brick leaf. I will seal to the window with insulation and air tightness, but am unsure what to re-fill the cavity with The cavity varies in size between 60 and 35mm, would seem obvious to use EPS beads. I thought maybe use an old bin to mix the beads and PVA and then out them in? Anyone got any experience or better ideas? It's only 1m high, and about 2m along.

Not yet- but working on it as part of renovation/ extension. Aim to be when I'm done. Mvhr going in as part of the same work.

Been searching and thinking and can't think of / find / work out how do air tightness well for my extension other than taping everything in sight like @plockhart is. The extension is going to be a warm flat roof attached to an existing cavity wall, with a new full fill cavity wall. Airtightness on new walls achieved with parge coat and old walls with wet plaster. Roof buildup so far is: - plasterboard - joists - OSB - VCL - Insulation - EPDM Can see how I can easily join the VCL to either wall, and therefore am I better just omitting it, and ensuring the OSB is vigorously taped to all joists / itself / the walls, or doing something different? I don't like the idea of the VCL below the OSB, as the OSB is then effectively sandwiched between 2 airtight layers and has a moisture risk. Grateful for wisdom / pointing me to the answer elsewhere.

I was pleased with the collingwood ones we had in our last place: https://www.collingwoodlighting.com/product-category/indoor/downlights/

Dodgy ubakus calc below. No idea what the aerated concrete blocks are I selected, and I changed the lambda value of the PIR to 0.019 to match k108. Note kingspans calculator suggests this as a way to hit u values, but no details on actual materials except the K108. @Caroline I'm assuming the celotex you were quoted is still a PIR board, so even though it's a bit cheaper, you still have a load of issues. As you say slightly bigger cavity. I.e. If you have a cavity of at least 130mm and do EPS or mineral wool batts you will save loads and have decent insulation.

It does with super light blocks. You can technically hit 0.18 I value.... Sounds like a rubbish idea though hence I changed my spec.

Yeah my builder specced the same. If you do a full fill cavity batt at 125mm you get basically the same u vale on paper: https://www.insulationsuperstore.co.uk/product/knauf-dritherm-32-125mm-cavity-wall-slab---2184m2.html * Note you might need to do something stupid like 130mm to pass building regs. Or just widen to 150mm. Side benefit, even at 150mm it's much cheaper than k108. At least half price. The same is true for EPS. Only issue I can see with EPS is the cosmetic element of holes. Not an issue if you are rendering though. Also see my discussion and calcs on it here: https://forum.buildhub.org.uk/topic/43093-cavity-insulation-and-air-tightness/

Ref airgap size: No idea. I'm a DIY builder and planning a warm roof. Just know an airgap is required. Aerogel: lambda value ranges from 0.015 to 0.023. So not much different to PIR. Another option is Vacuum insulation panels (aka VIP). They are a lambda value of 0.007 I think, made to measure and approx £200 a square meter. Would mean you stay between joists. Check out kingspan OPTIM-R. Re Q3. Not sure. Maybe. Re q4, it would be ok on 400centres. Much better than just taped (wet skim coat)

Mineral wool / EPS would increase your insulation depth required by 1/3. I.e. a total of 185mm. I think you are stuck with a cold roof buildup, so will need a ventilation gap no matter what.

Quick play using PIR if you just fill between rafters gives u value of 0.399. To hit the required Building Regs U value you need another 65mm of PIR. This assumes PIR of 0.023 R value. As I'm sure others will comment, it's great on paper, but really hard to do well unfortunately.