LaChab

@FarmerN Thanks for the observations. I had considered plastering the reveals, but now I've got to have at least 8mm gap around the window I'll stick with pb. Much easier to cover any tape.

@G and J I hadn't looked at that sort of tape. Looks an interesting alternative to gun foam. No, ICF with high density EPS reveals. @Gone West That's very reassuring. I'd be delighted with a reading anything like that. It seems that foam and adhesive tape is the way to go.

@Mike Thanks for the advice. I feel a bit reassured!

@Mike As it's into dense EPS I think they use screws. Good thought to ask specifically about underneath. I'm having the outside of the reveals rendered with 15mm stop beads before the windows are fitted, so would prefer to aim for a 7.5 / 8mm gap as you're suggesting. I do still think it's a bit poor that they can't use factory fitted tape though. @Mattg4321 I came across that when I looked up the Tescon profil stuff. Looks almost as good as factory fitted for pvcu windows. Trouble is I think they'll charge me £1050 for fitting it! Were you able to use it as you fitted your own windows?

@Mike The installer's almost insisting on 10mm, which seems ott to me. we've used an extension tube on the gun before, whic h would get it into 6mm easily. If I aimed for a minimum of 8mm, that sounds doable. But what about the bottom? presumably the foam gets completely squashed out there? You're right, it's ICF (Jackon). So no VCL. The reveal is really simple as there's just a 350mm closure covering both EPS and the core. Made from high density (120?) EPS and 45mm thick. Makes the windows very easy to install. I thought! Perhaps I just need to have more faith in FM330.

@Redbeard They are. And the limited width of the internal frame is why I don't think taping to it is the way to go. And worsened by the installer virtually insisting on a 10mm gap around the frame. I'm probably just being obsessive, but relying on foam for an airtight seal just doesn't seem right. I'll ask more detailed questions about fitting of some other Internorm dealers.

@Redbeard Just noticed that in the left hand picture it shows the Alu cladding.

@Redbeard You had me worried there! And I've seen them! Like you, I can't see it specified, but this description talks about the "hidden sash" from the outside.

@Redbeard Thanks for looking! I'm quite likely misinterpreting the diagram, but as far as I can see there's only about 15mm of frame on the inside, before the opening bit (25mm less about 10mm) And they're such nice looking windows!

@MikeSharp01 Exactly what they're saying to us! I can't really see how it can be damaged. Bet it's fitted ok in Austria! With a guarantee!

@Redbeard Sorry if I'm misunderstanding, but with a 10mm gap and 15mm of PB, there would only be <5mm for the tape. The factory fitted tape seems much the best, but what a ridiculous price!

@Redbeard I was intending to just line the reveal with plasterboard, so with a 10mm gap round the windows AFIC see that doesn't really give room to stick tape. Also we're intending to use KF520s, which have got a rather tight tolerance inside.

@Post and beam I'd like to! But the tape needs attaching to the sides of the windows before they're fitted. Which is what the £1050 is for apparently. So we'd have to fit the windows ourselves, and they're very heavy! @Russell griffiths That sounds interesting. I'll have a browse. Did you fit your own windows?

@JohnMo Thermal conductivity for the 330 is 36 mW/m.K. No idea how that compares! Illbruck say it's airtight (< 0.1 m³/(h.m) at 1750 Pa), but presumably it relies upon perfect installation. I've spect ages browsing "windows" on here, and I'd got the impression that an airtightness tape was very popular. There's certainly a good selection for sale.

Hi, I'd really welcome peoples views on the need for airtight tape when having windows fitted. I'm going through an Internorm quote for a new build, and I've been told that installation is with Illbruck FM330, but no airtight tape. I queried this and was told that for £600 extra they would fit ProClima Tescon Profil. I queried this as well, as it doesn't look like the correct tape to me, as it will show on the inside of the window. So latest, I can pay an extra £1050 and have factory fitted tape, just like on my existing 15 year old windows. But despite the cost, they won't guarantee it, as apparently it's easy to damage. It seems a bit mad to me to fit 0.7 glazing with only foam, but is that normal now? All help much appreciated.