There is a window in my basement where quite a bit of cold air is coming in. The draft is coming not from the window itself, but the space between the layers of brick. What is the best way to insulate around the window and as a bonus finish this window so it looks a little nicer?

basement window

basement window front

  • 2
    Is that flat board outside the window edge or inline with the jamb?
    – isherwood
    Jan 15, 2017 at 15:29
  • The wood framing is odd since it is actually smaller than the window. I've added another photo. Jan 15, 2017 at 18:23

2 Answers 2


Normally, windows are installed into masonry with a wooden "buck", a frame wrapping all sides with treated lumber. (See photos #1 and #2.) This is bolted and sealed to the concrete or brick. The window is installed inside the buck with a small gap, which is itself insulated and sealed, and a finished extension jamb is installed to the interior of the window frame where necessary.

In your case, the best you can do is seal all gaps with more spray foam. I'd mask the entire window with tape, then spray the brick face with thin layers. Wait until the foam expands, then add more if needed.

The gap at the top of the photo needs to be addressed, too. I'd probably fill i with fiberglass batt insulation. Stuff it loosely, but completely full. I'd need better photos of that area to offer more advice.

  • "treated lumber" could be mistaken for "pressure treated lumber"; which is a code violation, when used within the interior, in many, if not most, U.S. jurisdictions. Jan 15, 2017 at 17:08
  • 2
    Pressure treated lumber is a code requirement on indoor concrete slab where I live. I don't think that "...many if not most..." is accurate. Jan 15, 2017 at 17:19
  • Window bucks, sill plates, bottom wall plates and any other direct-contact application has required pressure treated lumber in my area for decades.
    – isherwood
    Jan 15, 2017 at 18:30
  • Yes, there is no "buck" for the window - it goes right to the brick. (There is wooden brick molding on the outside but i guess that just covers the gap between the window and brick and hides the foam.) Do you think it's possible to add an extension jamb in such a tight space? Jan 15, 2017 at 18:30
  • You can't add an extension jamb since your framing is where the jamb would be. Basically, the window is too large for that opening.
    – isherwood
    Jan 15, 2017 at 18:31

Foam is fine all around. Be sure to follow directions as it will take several passes.

Make sure your caulk is always looking good in the fall if you're in an area that gets snow, because it seems like that window's going to have snow melting against it in the winter.

Can also use standard insulation, I just prefer foam for smaller areas.

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