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Building envelopes In Ontario

H3Hans | Posted in Energy Efficiency and Durability on

Hoping someone may be able to point me in the right direction here. I am looking for some resources about building envelopes for Ontario Canada. Any recommendations would be greatly appreciated. Specifically looking for information related to air barriers, perm ratings and air tightness that isn’t written in code jargon.


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  1. Expert Member
    AKOS TOTH | | #1


    This is probably a good start:

    The reality is that the current OBC is pretty good, many of the assemblies in there would have been considered high performance a decade ago.

    Anything other that compliance package A1 has exterior rigid wall insulation, which is what you want for a good wall. If you want better than code, than go with thicker insulation.

    I wouldn't worry about permeability, just build to code. Flash your windows properly, tape your plywood seams, detail your interior poly well and you won't have issues. It never hurts to go with 1 perm or higher rigid insulation to get more outward drying.

  2. GBA Editor
    Brian Pontolilo | | #2
  3. Jon_R | | #3

    If you are going to run AC, then don't use poly on the interior. With that, do worry about exterior perms (> 1 perm is best). See here for info.

    1. Expert Member
      BILL WICHERS | | #4

      The OP is asking about Canadian code. I’m pretty sure Ontario building codes require interior poly in the walls. My brother in law is a builder over there, and every site I’ve seen has had interior poly and extensive detailing.


      1. this_page_left_blank | | #5

        It's pervasive, but not required by code. A vapour barrier is required, but there's nothing saying it has to be PE. My house has 7/16" OSB as the vapour barrier. The code specifically mentions both coatings on gypsum and the insulation itself being the vapour barrier.

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