Onoff

You could counter batten at this point. First foil tape all the joists and PIR joints. Make sure the wires coming through are sealed. Counter batten deep enough to suit low profile downlights then plasterboard. It's what I should have done.

I have to do some "reinstatement". I've compromised my vcl in so many places: The fire hood will be stuck down where it's rim meets the foil/vcl: Edge of foil and vcl: With hindsight I'd have done a suspended ceiling!

Did none of you save those Bazooka Joe wrappers as kids?

30mm is a massive width to fill. You really need backer rod or something.

You could fill with foam backer rod - cut to fit. Tbh you can use cut down pipe insulation. Then I'd over seal with white BT1 not CT1. White CT1 will go yellow over time. Cut down insulation used as backer rod. Alternatively do you have any uPVC window board etc left over? Cut and stick on again with BT1. https://www.toolstation.com/bt1-ultimate-bathroom-adhesive-sealant/p74523?

As with airtightness, the Devil is in the detail!

Over Sexed Bristolian.

I assume you mean on the inside? That second Illbrück video I link above shows taping the window to the frame. Starts about half way through. As for foam then the Illbrück FM330 stuff stands head and shoulders against all the other foams out there imho. "hardly anything for the compriband to stick to" It really doesn't need much of an unsealed gap to lose heat / get a draught through.

For example. The tape I'm on about, colloquially called "compriband", whatever the make, expands massively to fill the gap. You can get it adhesive one side that you stick to the window frame JUST before it goes in. Or tape you push in afterwards.

Some of the black washers are formed conical.

That's an access/rodding point for cleaning the trap out. Try turning the rubber washer around. You need to be 100% sure it's not leaking from higher up and running down to there.

I agree but Jet Blue isn't a sealant per se but a joint compound.

Where the white meets the black? Going to be a bitch to get any PTFE tape around there for instance. In the white bit there should I think be a black rubber O ring and a solid backing washer? The backing washer compresses the rubber. Think I'd try and smear the threads with say Jet Blue Plus.

It's really not hard to get a seal there if the right product was used. The expanding tapes are great for this sort of thing. Expensive and you need your wits about you to use them. Sadly the average bodging builder will resort to foam, cheap foam at that and often after the event. Would it pay in the long run to have the windows removed and refitted?

Understood. Sadly all these little areas basically add up to one damn great hole in the airtight fabric was how someone here put it the other day. A great if sobering analogy.

Surely the windows were sealed around? Are you meaning there's no Compriband/foam between window frame and structure or no airtight tape inside?

Do you have any details / pictures of the area where you had to compromise? Reading above it sounds like where the ends of the joists abut the wall there's a continuous missing airtight layer? That is a horrible problem to have. I think though someone on here did address similar, taping around the ends of every joist and possibly using an airtight paint. I'll try and dig the thread up. It sounds like a poor design unfortunately.

No offense but you're sort of missing the point. Having passive (or better) levels of insulation and airtightness are what leads to very low energy bills. Do it to current building regs requirements and you're already on a loser. Every compromise is lost heat. As I always do I'll come back to Jeremy Harris's comment. Even with 300mm of EPS under his floor slab, 8% of his heat losses were through the floor. That's a continuous concrete slab with just a few service penetrations. There are then self builders on here who's houses aren't Passiv certified but have exceeded those specs.

I feel for my new neighbours. Same basic house construction as mine, circa 1930. They've just re-roofed and ewi is yet to be done. In fact their planning application waxed on about the refurb resulting in a "thermal envelope". The external finish and attention to detail looks brilliant and they've had new windows. Not sure if they're 3G but they still appear to be in the outer leaf (it could tbh be solid brick with no cavity). The place was suspended timber floors, I don't know what they've done there. The work was done by their extended family who are builders. The thing is they have an ASHP fitted before things shot up. I'm wondering how they're fairing now. Hoping for a tour sometime. I watched their application proceed and on the basis of it am seeing the same local architect tomorrow hopefully.

Does an MVHR compensate for a too airtight build?

Does this thread not prove the massive attention to detail needed in building a Passiv ezque house? OK'ish airtightness just isn't good enough. Mass house builders doing it, like is being advocated in Scotland, never going to work. Blessed is he who asks for that 200mm of tape to finish off around his window.

Thanks for spelling out the obvious. Talking of semi's...

Not really, I've just had enough of nothing happening or moving forward here. I rang the bloke, sent him the original dormer extension plans then told her afterwards and that he's coming Monday. She did say "Well we've been talking about it for a while". Of course then had to get the last word in saying "But if we don't get permission we'll be scuppered and on their radar if we then do anything". Erm...state the obvious love!

A dog rough, fag packet sketch of what I suggested above. This is one method I've considered with my kitchen. It saves taking the kitchen units down to dig up and you really don't want heat going up into food storage cupboards or the fridge freezer anyway. It does of course mean you still have an insulated room perimeter. Another concern I had was that this might shift/settle over time and there'd be a noticeable "joint" between old an new floor sections. I imagine you would put a mesh or similar down before tiling the whole lot. I wouldn't do this in the lounge I don't think as we have furniture around the perimeter and I'd want heat coming up under that. Might be a moot point for me as really the whole kitchen floor is too high and wants lowering to match the rest of the house. This and the step up will become an issue for us in later life if we become semi immobile when older or wheelchair users. Hopefully we'll have frozen to death / been eaten by rats before then...

Rang a local architect with a view to engaging his services. He's coming to see me next week. I picked him based on 3 recent, local applications by neighbours all involving different architects. Out of the three, he seems to have the best grasp on local planning sensitivities.