Replies

1. Expert Member
   MALCOLM TAYLOR | Feb 27, 2020 07:56pm | #1

   Hobscon,

   Acceptable practically, or acceptable by building codes?

2. 
   Hobcon | Feb 27, 2020 08:19pm | #2

   building code. I'm in southern maine and the code office isn't familiar with the product

1. Expert Member
   Dana Dorsett | Feb 28, 2020 03:46pm | #3

   Does the code office read and understand specs?

   Download and print the spec, circling the relevant portions.

   Per the spec :
   ---------
   WVP Perms (US)
   As per ASTM E96 less than 1.0 perm
   grains/(hr ft2
   in Hg)
   -----------
   See: https://www.sherwin-williams.com/document/PDS/en/035777633175/

   Less than 1 perm = Class II vapor retarder.

   More short-form definitions from the US DOE:

   https://www.energy.gov/sites/prod/files/2014/01/f6/4_3b_ba_innov_vaporretarderclassification_011713.pdf

   Where / what type of assembly is the local code office demanding a vapor a barrier?

   Maine's residential code is based on IRC 2015, which includes the use of Class-II vapor retarders on wall assemblies:

   https://up.codes/viewer/maine/irc-2015/chapter/7/wall-covering#R702.7

   With a Class I or Class II vapor retarder the roof/attic ventilation requirements are cut in half:

   https://up.codes/viewer/maine/irc-2015/chapter/8/roof-ceiling-construction#R806.2

   The verbiage and relevant code sections didn't change between IRC 2015 and IRC 2018, so even if the local township has upgraded to the newer version it's still good.

3. 
   cmobuilds | Feb 28, 2020 04:35pm | #4

   Think the thickness of the coat (mils) is important. One inspector asked to see the empty buckets so he knew the coverage wasn't skimped. He didn't do the math though, he was just trying to flex.

1. Expert Member
   MALCOLM TAYLOR | Feb 28, 2020 04:46pm | #5

   Note to self: Alway keep several empty paint buckets on site!

1. 
   cmobuilds | Feb 28, 2020 04:58pm | #6

   Just write “vapor barrier paint” with a sharpie on some old buckets.