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Ok to use external poyfiller to install new wooden sash windows?

Hi, I have just had a bank of 5 wooden sash windows installed. I have noticed the installer has used expandable foam and polyfiller on the exterior/outside. I was under the impression sand, and cement, with pva as a waterproofing additive should have been used. Can anybody advise what are the correct materials to use on the exterior?

1 Answer from a MyBuilder Plasterer

Best Answer

Hi. Expanding foam to hold the window in place in the reveal is ok. If the gap on the outside is minimal then decorators exterior silicone can be used, but if the gaps on the outside are big, then either timber cover strips can be used if fixed in the right manner, or cement. But polyfiller is a bit weak.


Answered 7th Dec 2015

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