Expanding Foam on uPVC WIndows

Bobskillz

Should a window fitter use expanding foam when fitting uPVC windows? I had a new window fitted last year and a friend recently mentioned that the window is too small for the gap where its been fitted and to cover it, the fitter has used expanding foam which apparently, he shouldn't have done.

FreeBear

uPVC frames are usually 5-10mm smaller than the hole in the wall. Expanding foam is usually used to seal this gap, and then a layer of mastic applied on the outside (sometimes with a plastic trim). There should also be some mechanical fixings (ruddy great screws) to fix the frame securely in place.

Larger gaps should have filler strips inserted where appropriate, but they should not be used to hide the fact that the frames were made too small - How big are these gaps of yours, and are they of a consistent size all the way round ?

stuart45

When they measure up for a new window it's taken top, centre and bottom, and the smallest measurement it used less enough mm to get the new window in. 
Foam is standard, it actually helps hold the frame in place.

Section62

stuart45 said:

Foam is standard, it actually helps hold the frame in place.

^This.  I'm not sure what the friend thinks would be a more appropriate material to use.  (hopefully not mortar)