When installing retrofit windows, what type of insulation works best overall? Fiberglass, open cell foam tape, or spray foam?
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| Posted in Energy Efficiency and Durability on
When installing retrofit windows, what type of insulation works best for overall performance? Fiberglass, open cell foam tape, or closed cell spray foam?
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Bradley,
Retrofit window installation does not usually require any insulation improvements to a home.
Perhaps you are asking about air sealing the gap between the new window frames and the rough opening?
Brad
I figured you meant the gap between the window frame and the rough opening. Use a minimal expansion foam specifically for window installation so you don't warp the window frame and cause operation problems. There are a ton of manufacturers. I personally use Todol products that I get from EFI. Fiberglass insulation is not an air barrier and a waste of time and effort. More than likely the old gaps were filled with pieces of batts. They are usually covered in black, which is a sign of air infiltration. I have never used open cell foam tape (unless you are referring to weatherstripping) I personally would not use that either because the adhesives on the tape fail over time.
My trick, I oversize rough opening which gives me more room to fit low expanding spray foam in deep. I just seal the deep area, then add fiberglass to fill out area. The fiberglass stops the foam from frothing out and then needing to be removed.