new windows
#1

I'm installing new windows into existing rough openings. I have gaps between the new windows and the existing openings, 1/4" to 3/4". What would be the best thermal seal? Foam? Thanks.
#2
NOT foam. It will set up too hard to allow the window frame to expand and contract as it needs to. Use fiberglass insulation, and put it in loosely, so it maintains its 'fluff'. Get it in rolls sold as pipe insulation at any hardware or big box store.