Replies

1. GBA Editor
   Martin Holladay | Apr 16, 2019 11:55am | #1

   Ryan,
   A minimum of R-10 of continuous insulation, according to most codes.

2. Expert Member
   Dana Dorsett | Apr 16, 2019 11:58am | #2

   R100 would be great!

   The IRC calls out R10 minimum.

   Pick a number between 10 and 100...

   If you have access to a foam reclaimer even 4"- 5" of roofing EPS (usually Type VIII, 1.25 lbs per cubic foot) is substantially cheaper than 2.5" of virgin stock Type II (1.5lbs ) or Type IX (2.0lbs.). While less dense foam takes on more moisture into it's interstitial spaces when in soil contact, even Type-I (1.o lbs) delivers better than R3/inch unless the soil is completely saturate (is building in a swamp that requires sump pumps to be working 365 days /year?)

3. 
   rhl_ | Apr 16, 2019 12:27pm | #3

   Thanks guys. I know EPS is preferred. We are having some trouble sourcing EPS, the reclaimer people don’t have stock at the moment. We are doing 3” of XPS. I wanted to do 4” but the contractor is making a stink, so Im living with 3”. It’s better than nothing.

1. Expert Member
   MALCOLM TAYLOR | Apr 16, 2019 12:51pm | #4

   "It’s better than nothing."

   It's better than R-1o.