Replies

1. Expert Member
   Dana Dorsett|Feb 11, 2015 05:31pm|#1

   The vapor permeance of 1.5" pink board is about 0.6-0.8 perms, which is a bit on the tight side, but still OK as long as there is still ventilation space between the foam and siding. Unfaced 1.5" EPS would have about twice the drying capacity.

   Even though you wrote "... between the nailers on the outside of the vapor barrier..." it sounds like you're actually putting the foam on the interior side of the vapor barrier? If that's the case- the foam is on the interior side of the assembly, you'll get somewhat better performance out of 1.5" of foil-faced polyiso than you would out of pink board, and the cost may even be cheaper.

2. 
   wjrobinson|Feb 11, 2015 07:52pm|#2

   No plans?
   No permit of said plans that must be followed or amended?
   No builder with appropriate knowledge?

   How can someone post in the middle of building a project the need for specifications?

   I have never ever started a project that needed plans and permits like how people post here at GBA.

   I don't get it, someone clue me in. I must be stupid.

3. GBA Editor
   Martin Holladay|Feb 12, 2015 08:30am|#3

   Dennis,
   I agree with Dana that your description is confusing. Do you plan to install the rigid foam on the interior side of the polyethylene vapor barrier, or on the exterior side?

   我们不知道你的位置或气候区, so it's hard to provide advice. In general, this type of building definitely needs a good air barrier as part of the wall system -- but in most climate zones, it doesn't need a polyethylene vapor barrier.

4. GBA Editor
   Martin Holladay|Feb 12, 2015 08:32am|#4

   AJ,
   I'm happy to explain things to help you with your confusion. By now, AJ, you should know that there are many regions in the U.S. where there are no building codes and no need for building permits. I live in such a region.

   One reason that some jobs don't have a builder is that owners do the work themselves.