Hello all

I should be having some new double glazed uPVC windows installed in about 1.5 months. I know if left to their own devices the installers will do the bear minimum - ACME expanding foam round the edges and finish with a trim. I want a better job done so been looking at alternatives. One of them is this expanding foam which is a little pricey:

https://www.partel.co.uk/product/conpreseal-3v-bg1/

Alternatively this expanding foam doesn’t look too bad:

http://www.soudalairtight.com/INT/raam_schuim.html

Has anyone used any of these products or similar? Is it worth spending the £130 on the expanding foam tape when this expanding foam will do?

Thanks

He's not talking sticky 'sellotape' but Compriband-style expanding gapfilling tape. I use the latter plus gunned sealant as well - not sticky tape.

Posted By: fostertomHe's not talking sticky 'sellotape' but Compriband-style expanding gapfilling tape.

I have not found this type of tape to be able to withstand exposed conditions. Continuous driving rain in very strong wind saturates the tape which then acts like a downpipe and directs water downwards until it finds a weak spot. It is great to get a nice clean finish between opening and frame but I had to put behind it a silicon bead supported on polyethylene rod of appropriate diameter for the gap. Internally gun applied expanding foam for the internal gap.
Make sure the installers mechanically fix the windows and not rely on the foam to hold in place. It is part of the regs.

Previously: http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15311&page=1#Item_8

We talked before (but can't find it now - anyone?) about

Posted By: revorContinuous driving rain in very strong wind saturates the tape which then acts like a downpipe and directs water downwards until it finds a weak spo

and

Posted By: Mike1does need impermeable vertical and horizontal trays behind it to drain water

and I thought a way emerged to escape that risk/mitigation.

I used loads of their FlexiFoam - wonderful stuff.

To clarify from the OP, is this inside or outside sealing, air tightness or weather proof?

External, My reveals are rendered but I used a stop bead so that there is a gap of about 15mm between the stop bead and the frame. This was filled with EDPM expanding foam tape. Very watertight works a treat (10 years old now).

Internally and airtightness, I suspect you will need to do more. I'd be inclined to ask them to leave the inside unfinished and finish it myself. Soudal Flexifoam is wonderful as it expands but does not push against what it finds. Make sure that is what you get as it looks like it isn't as readily available as it was (it is blue) and there may be products purporting to be it around. https://youtu.be/xH8SfIooXYo

What about closed cell backer rod instead of expanding foam?

I'm currently looking at windows and after speaking to a few passive installers most are using tape, one of them claimed they have been using it to install internorm windows for 10 years and haven't had any issues. I have been explicit in stating that our house is extremely exposed (on a hill) and gets battered by the weather and have been assured correctly installed tape should be fine.
I believe a critical stage in the installation is to get the butt joints correct so they expand up to each other tight. Not personlly used it yet but I will be shortly.
I'm planning on using it in conjucntion with Souda window and door behind as above. My experience with gun foam is that you really need to pay attention to the instructions and thoroughly remove dust (I blow out with a compressor) and then damp down prior to application. It's especially important on masonry to ensure proper adhesion otherwise you may find it pulls away over time. I've watched quite a few tradesmen applying foam and have yet to witness one following instructions as above. Some of them have been very pedantic about their joinery but seem blissfully ignorant of how to use foam. If you want it doing right............

Thanks Mike

Thought this looks a good thread to add to:

Aluminium or aluminium-clad windows going onto an external skin of a cavity wall
EWI to follow

What would be the best way to ensure air tightness of the fit?

Used flexifoam from soudal this summer, it is brilliant.
Think about cavity closures and insulating reveals in case external insulation bypassed b6 cold somehow. I used air tightness tape too.

I used compriband expanding foam tape for upvc this summer but put good silicon seal on outside on advice from builder, some gaps were too small to tape. I would just flexifoam in future.

Posted By: LFsome gaps were too small to tape

I don't understand this. How can a gap be too small to tape?

If we go with Ali-clad windows I will install with my chippy

If we go Ali I will leave to the fitters who have said they will seal up with EPDM

CWI will be done by subcontractors

EWI will be done by my team to board and then get a silicone render specialist in

Posted By: LFI am talking about compriband foam gap filler not air tightness tape.

Ah, sorry. I don't think of Compriband as tape.

Posted By: fostertomOK, so what about Compriband-type expanding-strip sealant? I guess, at the right thickness, it's good when continuously clamped, even to say a roughcast render surface. What about the practicalities/effectiveness of applying it around all four (or maybe three) sides of a window reveal (whether masonry or timber) before quickly putting the window into place before the strip expands?

AIUI, normal practice is to put the window in place first, and then put the Compriband in the gap before it expands.

Do you then seal up after the expansion tape?