Airtight tape on 3g windows. Or not?

[Mike]

14 minutes ago, LaChab said:

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?

I aim for 7.5mm (all round) to give some tolerance - so it it ends up being 5mm or 10mm, no problem. I wouldn't object to 10mm too violently - it's just that if it ends up at 12.5mm in practice, then it starts getting fat for the external sealant. I'd ask them what their plans are for underneath - it could be that they'll also fix the window using mechanical brackets down the sides. Or they may plan to use temporary wedges (not all the way through) while the foam sets.

 

[Mattg4321]

I used this stuff as it was pretty cost effective against the competitors. Also bought their primer for taping to lightweight concrete  blocks. Very very impressed. Was almost impossible to pull off even if you tried.

 

https://passivehousesystems.co.uk/product/phs-modbau-internal-window-tape/

[LaChab]

@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]

15 minutes ago, LaChab said:

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.

Suggest that with your reasoning & see what they say.

 

15 minutes ago, LaChab said:

Tescon profil stuff

I've used Tescon Profil too - it's easy enough to use, just takes a little time. Have some acetone on standby to clean your hands and scissors as it's rather sticky.

 

Edited 14 hours ago by Mike

[LaChab]

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

[G and J]

I’m assuming this discussion is referring to gap covering type tape.  
 

When I visited @Nick Laslett he showed me the expanding foam tape he had used.  Is that not an option?

 

I think it goes between window frame and whatever the fabric of the house is, thus no tape showing issues. 

[Mattg4321]

8 hours ago, LaChab said:

@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?

I didn’t fit my windows and in my case the tape was fitted afterwards by me and covered by the plasterboard reveals. I used 15/55 split. 
 

Guess it depends on your build type as to whether it can be fitted afterwards though. 

[Gone West]

Our windows were fitted with two rows of Compriband and foamed with Soudal Soudafoam Low Expansion foam. The windows were strapped to the reveals. I didn't use any type of airtightness tape or membrane and achieved an airtightness reading of 0.47ACH.

[G and J]

17 minutes ago, Gone West said:

Our windows were fitted with two rows of Compriband and foamed with Soudal Soudafoam Low Expansion foam. The windows were strapped to the reveals. I didn't use any type of airtightness tape or membrane and achieved an airtightness reading of 0.47ACH.

Is your house timber framed?

[LaChab]

@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.

[FarmerN]

Our Rationel alu clad /wood windows had internal split tape, then Illbruck FM330, and Compriband expanding tape as the external seal .

The internal tape provided a very visually convincing seal, whether it was really needed I have no idea.

We did however have trouble covering the tape with plaster and ended up putting beading round the reveal to hid excess tape on the frames. Which actually looks fine.

Removing excess tape is impossible and our problem covering the tape arose through using wet plaster on the reveals not plaster board.

My point is if using internal tape , as already said in earlier posts, take great care tapping accurately and know how you are going to cover it on the frames.  

The external Comriband tape worked well against our brick walls and looks very good. Time will till what it will look like in 10-15 years time.

[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.

[Gone West]

1 hour ago, G and J said:

Is your house timber framed?

Yes it was.

[ToughButterCup]

16 hours ago, LaChab said:

....

I'd really welcome peoples views on the  need for airtight tape when having windows fitted.

...

 

Several thousand spent on the windows from heaven, and you are concerned about a few hundred on airtight tape : fitted by someone for you - that means £200 a day labour costs.

Hmmm. 

And if the subsequent air test shows a leak where there should (have been)  tape, the remedy is a phone call away.

Hmmmm. Hmmm.

 

JBDI

JustBloodyDoIt

[JamesP]

Exactly what @ToughButterCup said. 

[LaChab]

@ToughButterCup @JamesPI think you've misunderstood.

I posted my query as I had doubts about the effectiveness of using only foam to install the windows, when my existing ones have got factory fitted airtight tape.

I also couldn't see how "face fitted" tapes were feasible.

Actually what I'm most concerned about is the installer being unable to guarantee the work if I specify factory fitted tapes.  It gives me no confidence in their abilities at all.

I do also think that charging an extra £1000 to fit the windows if I want "pre fitted" tapes is a bit excessive. I'd assumed that that was standard!

 

[JamesP]

59 minutes ago, LaChab said:

@ToughButterCup @JamesPI think you've misunderstood.

  It gives me no confidence in their abilities at all.

Rightly so, I built most of my (airtight) house except door and window fitting (Internorm), electrics and skimming. The fitting was very poor, I just wanted them off site and spent many hours finishing the fine details using some foam and lots of tape. They only used compriband.

Not quite sure how far inbound of the frame towards the reveals lies the responsibilities of window fitters ? 

Don't trust them much.