replacement window fitting - expanding foam or expanding tape

[riccol1966]

Hi everyone, I'm sure you all have an immediate answer/preference here, but can I ask what is recommended when looking at replacement windows and how window fitters seal the windows into the opening. I've just visited a site where a well known window company used Wurth expanding window foam, I was looking at the can being used and it's clearly designed for windows, has a fine cell structure and of course will fill every gap, especially around the spacers used to ensure a square mounting. On the other hand I was under the impression that expanding tape such as compriband was recommended but then I notice a number of forum posts which indicate difficulties with the tape, particularly if the gap is not consistent and how it works when butting up against the window spacers/packers and how to maintain an airtight seal with the tape. 

 

I wonder do some companies choose one method over the other based on installation speed and cost, and there's also the question of how well foam or tape perform over the 20 year lifespan that you would expect from the window itself. I would appreciate any feedback here from those more knowledgeable than me in this area, 

 

Best regards 

 

Richard. 

 

   

[Mr Punter]

You need the foam in any case as an insulating layer on the inner part of the frame.

 

The expanding tape is then used on the outer part of the frame to seal to the structure.  If you don't use tape you can use a mastic sealant.

[gravelld]

Most firms use just foam or mastic because that's what installers are used to.

 

But you're best off with tape long term. Make sure the installers have experience or have someone to teach them on site.

[craig]

Just PU foam, you don’t need anything else.

[Onoff]

Must have been the fastest window fitters in the west did some of mine. When I removed the plastic trim the gaps were huge! Still a number to do.