I have a home that is over 50years old. The basement window opening, (casement) is Steel. build into the home. Not removeable. Can’t screw into it. I am thinking the STEEL gets cold. Wondering if there is an ‘Insulation’ to put around the replacement windows when I install them to keep the cold from transferring to the windows? Any recommendations? Will the spray foam insulate it enough. Should I shim it with something? Felt tape? Not sure what would work. Thanks for any advice. (ps, I’m 76 never done windows. Always a first time for this old lady)
Welcome to the forum Barbara. You are just a little older than me and certainly young enough to organise this.
Are you able to post pictures of the window from inside and out? Also, could you consider a somewhat smaller window by the time work is done?
Hello Tim, Yes, I am installing a slightly smaller window. I’m just preparing with everything we will need before we remove the old windows… Spiders… heat… dirt… Keeping the runs to the hardware store down.
Trying to think of everything before we begin.
Spray foam, Caulk, etc.
So you have the new window already? That may limit the options. How much space have you allowed for?
I am ordering them tomorrow. I just cleaned the window wells and measured. About an inch on the sides to 1/2 inch on top. Might be a bit more . The window ledge isn’t flat, It has a raised lip. I’m just wondering if an insulation would be recommended? I can order whatever size I need.
Thank you
How wide is the metal casement and how thick is the wall? Is the wall insulated or are there plans to insulate it?
If insulated what is the thickness of the insulation? Being a basement I assume any insulation is internal, unless perhaps this is an exposed wall of a half basement, in which case external insulation is a possibility.
How thick is the replacement window frame?
These are ‘average’ size. Nothing special. Basement windows so I’m not spending thousands of dollars. Just want to keep the bugs and the cold/heat out. I was thinking like a ‘felt strip’ around the outer edge of the windows. Something like that. So as not to transfer the cold from the steel to the window. Am I over thinking this?
I’m guessing from your reply that the basement is not routinely occupied. The standard of insulation does not need to be so high if that is the case but you still don’t need the warmth of the house being sucked out from under the floor.
If at all possible I would move the new window in or out sufficiently to abandon the current metal sub frame and then use expanding foam tape to make an airtight, water tight, insulating seal. There are discussions elsewhere on this forum about tape use. I’ll have a look and then add a link here.
Thank you for your responses. I think we figured it out. We will ‘wrap’ the window with a felt band to give space between the window side and the Galvanized Steel frame. We will use foam after installing to insulate the gaps and keep the window efficient. Then frame the window on the inside.
p.s. Yes, the basement is finished and is occupied. It’s a 2 bedroom, 1 bath, den, office, laundry room with a cement floor. Finished many years ago. It’s below grade so I doubt if much insulation was used. It stays warm other than the 60 year old aluminum framed, single pane, windows. That is what we will remedy. I’m looking forward to it. Thank you for you time and input. Barbara
Hello to everyone!
First off, good for you for tackling this project! It’s a great question, and dealing with old steel casements is a common challenge in older homes here in Idaho.
You are correct to be concerned about the steel transferring cold; it’s a major source of drafts and heat loss. Spray foam is actually the right product for this job, but it must be used correctly.
Here is the best practice for insulating a replacement window in a steel basement opening:
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Dry-Fit the Window: Before applying any foam, place the new window into the opening to check the fit.
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Use LOW-EXPANSION Foam: This is the most critical step. Do not use the standard “window and door” spray foam, as it expands with too much pressure and can warp the frame of your new window, making it impossible to open and close. You need “Low-Expansion” foam specifically.
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Shim for Stability: Use composite or plastic shims to hold the window perfectly level and square in the opening before you foam.
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Foam the Gap: Apply the low-expansion foam in the gap between the window frame and the steel casement. Fill the gap about 1/3 to 1/2 full—remember, it will expand.
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Do Not Disturb: Let the foam cure completely according to the can’s instructions before trimming off the excess.
While this is a doable DIY project, the combination of a basement installation, a non-standard steel frame, and the precise handling of foam and shims can be tricky. A professional installer deals with this regularly and has the right materials and techniques to ensure a weather-tight, insulated, and problem-free installation.
A company like ours (CK’s) handles basement window replacements like this all the time. We would take care of the sourcing, the low-expansion foam, and the proper installation to make sure your basement stays warmer and draft-free.
For reference, low expanding, closed cell, foam is available in the UK. I bought some a while ago from Travis Perkins, who I believe have branches throughout the country, but it was necessary to order from their web site, which I did Click and Collect. It took several days to supply. Alternatively you could try one of the eco builders merchants.
Choose shims that are less likely to cause a thermal bridge or use ones that are less than half the frame depth with staggered support from inside and outside the frame.
When foaming I never assume that some path for air movement hasn’t been left and add airtightness measures on the inside.