Radiant barrier on rafters or directly on deck?

[ctgottapee]

See page 6 of that pdf for where the air 'pocket' should be.

Stapling directly to the deck is effective in the south, as you are preventing heat from radiating down from the sun heated deck, the air pocket being the attack space. Proper attic venting {in a vented attic} eliminates some of these gains as far as installed Rvalue.

Preventing radiating outward toward the deck isn't really an issue, and the dynamics of it don't make for promising Rvalues even when it is. That insulation maker use to provide a diagram on it's label showing relative Rvalues in various situations so you could see the differences.

Note the issues others have mentioned, like keeping it clean, etc.
Also if you don't loop over the rafters, you are skipping a portion of the roof deck and will lose some benefit.

Your best bet would be to return the product and buy a much lower cost wide roll of pre-perf aluminum foil that you can find online or via most lumber yards.

Originally Posted by Brandon727

I'm going to be installing a radiant barrier this weekend, Location lower Central Florida so my only goal is keeping the heat out.
From everything I've read radiant barriers need an air pocket to be effective, but the manufacturer of the radiant barrier suggest you can staple it directly to the deck if in a southern climate. I assume they suggest that method in the south to keep heat out.
Page 3 here http://pdf.lowes.com/productdocument...hRQXZEX0J3RQ.. advises a direct to deck staple method.


Should I hang it between the rafters creating an air channel, or should i staple directly to the deck?