So my partner and I are working to restore an old interior brick wall (about 100 years old). We have stripped off the plaster and cleared out all the loose, crumbling mortar in some sections of the brick. But this has left some gaps, particularly between the brick wall and the wooden sash window frame.

We are a bit stuck on what is the best material or combination of materials to fill it with. Our thinking is to fill the gap between window and brick with expanding foam and then use a lime mortar or lime putty over the top of the foam. We would also repoint some sections of the brick using the same soft lime mortar. Is this a good idea? We would appreciate any advice!

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  • Thanks for your reply! Added a photo. Our goal is to repoint the wall and to have it as an exposed brick internal feature wall. Just not sure about filling these large holes. Particularly around the window frame.
    – Laura B
    Aug 28, 2023 at 21:34
  • Your photo doesn't show us much. The critical area is in deep shadow.
    – isherwood
    Aug 28, 2023 at 23:39
  • To be clear, this is the interior side of an exterior wall—correct?
    – Huesmann
    Aug 29, 2023 at 12:58
  • Welcome. Please take the tour so you know how to use this site.
    – isherwood
    Aug 29, 2023 at 13:24
  • I lifted the shadows in the photo so you can see in the hole better. Looks like a double-skinned wall, possibly even with an air-gap [though I'm not sure how common a gap was a century ago]
    – Tetsujin
    Sep 9, 2023 at 13:28

1 Answer 1


This seems like a classic case for mortar pointing to me (often called "tuckpointing", though somewhat erroneously). It was filled with mortar before and that's the right thing to fill it with again. It'll look right and be solid.

There's little benefit to be gained from trying to add insulation, but it may make sense to caulk from the outside to seal against drafts.


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