What is the recommendation for plugging a 3 inch gap for installing an air conditoner.?
Answers:
You can use a product called Great Stuff, which is a foam filler. I would then seal it well with a caulk called Phynoseal.
Other answers:
No foam will not(by itself). But use a piece pf wood with the foam.
No foam will not(by itself). But use a piece pf wood with the foam.
You can use the foam but sometimes it can get real messy and then you have to worry about what it looks like after. Try the filler kit I suggested earlier.
A piece of wood. You can get pre-painted/finished trim pieces that are easy to cut and install. Look at any of the big hardware stores. Back it with foam for insulation and stability.