Basement window measurement
#1
03-25-08, 07:44 AM
Join Date: Nov 2005
Location: Northampton, PA
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Basement window measurement
This summer I'm going to replace two old hopper windows in my basement that has a poured foundation. I've been reading here in the forum on measuring but I haven't come across this in any posts. My rough openings are 32.5" across the outside but 33.5" across the inside where the old frames meet the concrete. It doesn't appear there is any major application of mortar on the outside to account for the narrower measurement It just looks like it was poured with a .5" lip on each side and the bottom. Did they do it that way in the '20s when the house was built? If so I should get replacement windows that fit the inside measurement and but up against the lip on the outside. Correct?
#3
03-25-08, 04:15 PM
Group Moderator
I'm guessing that you have a cinder block foundation? Or is it a poured foundation?
If you can see the mortar lines on the cinder block on the inside, but can't see the mortar lines on the outside, then it's likely that the entire exterior has been skim coated (parged) with some type of mortar. Once you find this out, then you'll know.
You could also tear out 1 window and then cut a piece of 3/4" CDX plywood to stick back in the hole, and temporarily anchor it in place with some 2x4's and tapcon cement screws. When you're unsure of how to measure, tearing out a window is often better than just guessing and hoping you have it right.
If you have parged cement on the exterior, it could be that you'd go with the larger interior measurement since your windows would likely push up against the exterior parged cement as if it were an exterior blind stop.
But you'll need to figure out if it's parged or not.
If you can see the mortar lines on the cinder block on the inside, but can't see the mortar lines on the outside, then it's likely that the entire exterior has been skim coated (parged) with some type of mortar. Once you find this out, then you'll know.
You could also tear out 1 window and then cut a piece of 3/4" CDX plywood to stick back in the hole, and temporarily anchor it in place with some 2x4's and tapcon cement screws. When you're unsure of how to measure, tearing out a window is often better than just guessing and hoping you have it right.
If you have parged cement on the exterior, it could be that you'd go with the larger interior measurement since your windows would likely push up against the exterior parged cement as if it were an exterior blind stop.
But you'll need to figure out if it's parged or not.
#4
03-25-08, 07:22 PM
Join Date: Nov 2005
Location: Northampton, PA
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Thanks for the replies. My foundation is all poured. I know I've read many places to measure for new windows from the outside so I guess I would be looking for trouble if I went with the inside measurement. I like the idea of tearing out one window and see what situation I have.
#5
03-25-08, 07:42 PM
Group Moderator
I guess it's possible that the window was installed during the pour and there are different levels surrounding it. So yeah, if you can tear a window out to ascertain the rough opening, I'd say it would be well worth it.
