I'm looking to replace a basement window and I'm unsure about how to measure it correctly. Should I measure from the very edge of the metal frame (like the yellow line in my reference image) or from inside the frame (like the red line), or is there another method I should be following? Any tips would be appreciated! Thanks!
1 Answer
When measuring for your new window, you need to focus on the actual opening size, which looks like it corresponds to the yellow lines in your image. I recently replaced two of my windows and first demo'd the old one to get a clean opening. I measured it carefully and ordered my new windows 1/4" smaller than the opening, which worked out great. I also used spray foam to fill any gaps and finished it off with caulk around the edges.

Got it, thanks! So the yellow lines are indeed where I measure from. How did the 1/4" undersized work for you? I hear different opinions about how much to go undersized—some say 1/4", some 3/8", and others 1/2". Did you need to drill into the frame, or did the spray foam and caulking hold everything in place?