Had to choose between spray foam and rigid board for my attic last month

I spent three weekends reading forums and watching videos trying to decide. The foam guys quoted me $2,800 for a full spray job which seemed steep. I went with 4 inches of rigid foam board with taped seams for about $600 instead. Turns out the rigid board is actually outperforming what my neighbor got from his spray foam contractor. The install was way easier than I thought, just time consuming cutting around the trusses. Has anyone else here tried the foam board route and found it worked better than they expected?

2 comments

2 Comments

grantthomas1mo ago

Exactly 4 inches is the sweet spot for rigid foam in most attics. I did the same thing two years ago and my utility bills dropped about 15% that first winter. Just make sure you seal every gap with canned foam or you'll lose all that R-value.

the_keith1mo ago

Exactly 4 inches is the sweet spot" nailed it. I did the same and found the canned foam for edges made a bigger difference than I expected, worth the extra hour of work.