# Cement or Foam to fill basement window cutout gaps



## seavlad (Sep 22, 2016)

replacing small basement window, 18x36, in 8" poured foundation. Builders poured around window frame so inside sill and sides have 2x4 cutouts when old window was removed... and the sill has a couple concrete gaps in the middle as well.

RO framing with 2x10 PT and debating two options..

1. cement sill flat (recommended mix??)
OR
2. block inside sill gap with PT 2x4, then fill gaps with foam and set 2x10 sill

Foaming seems a lot easier and don't need cemented based to square framing


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## P42003 (Jun 15, 2016)

Does the room need an egress window?


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## punxsy (Sep 27, 2016)

Foam seem easier. Foam somewhat serves as a vapor barrier, which is something to think about, anytime wood is near masonry. Also, masonry has very little R value.


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## Herminigilde (Apr 10, 2012)

We pretty much always frame to fit if needed then use foam in basement/concrete wall replacements. I can't remember ever mixing cement/mortar. 

I'm interested in other opinions...


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## Lettusbee (May 8, 2010)

I used to retrofit a lot of egress windows, and every once in a while, the concrete cutting guy will get a little carried away, leaving us with less than perfect openings. 
We will use precision non shrink grout in those cases. Not because it does any thing for our structure, but it because it's easy to work with, especially on vertical forms. It also works well with a grout bag.

https://www.quikrete.com/productlines/nonshrinkprecisiongrout.asp


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## heavy_d (Dec 4, 2012)

noward said:


> Foam is much better than using cement.Foam may act as a barrier to fill up the gaps..so I think its better...


Just curious what you mean "foam may act as a barrier".

Sent from my SGH-I337M using Tapatalk


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