[topfiverecords]

Originally Posted by Shin Pad

Here is the thing about how you call things up on the drawings and in the specifications. Suppose you are doing a project where a portion of it is commercial construction with a backup wall, with air/vapour barrier (self adhered membrane) on the exterior side of the wall and insulation and cladding outboard of that, and then you have a portion of the building that is residential type construction with the traditional stud with batt insulation type construction, with a polyethylene sheet on the inside face of the studs and a building wrap material on the exterior side of the sheathing. So you are calling up the materials as an air/vapour barrier (on the commercial portion), a vapour barrier (poly) and air barrier (building wrap) on the residential portion. This could create confusion on site and in the bidding process. What if the contractor comes back and asks for an extra because he priced out vapour barrier (poly) on the commercial portion during the tender period instead of what you wanted which was the self adhered air/vapour barrier. I have seen this being tried by Contractors - they will try and get an extra on anything they can. So to avoid any confusion, you need to make sure you use the right nomenclature throughout your documents. So I would call the building wrap - exterior sheathing membrane. I would call the poly - vapour re_tarder and I would call the self adhered membrane air/vapour barrier. I would have a separate specification section for each material and the drawings would call out these materials using the same nomenclature so there is no confusion, it's absolutely clear which material goes where. Anyway - another reason for making the distinction between air/vapour barrier and vapour re_tarder.

And if you shaped it into a cup form you could call it a bag, or if you lay it flat in your yard you could call it a tarp or any other non-applicable distinction you want to make. You're killing an ant with a sledgehammer here and that just drags the topic away from the original point of use in a single family wall and ceiling assembly.

Originally Posted by Shin Pad

I know in single family residential, you don't have specifications (other than some notes on the drawings), and you are just using 6 mil polyethylene sheet, so it probably doesn't matter what you call it.

We don't have specifications other than some notes on the drawings? Huh?

It doesn't matter what you call it either after it's been installed which is what we're talking about here and not a specification situation on a multi-use development.

Originally Posted by Shin Pad

I have never seen the term "barrier challenged" before, but the important thing is, what you end up with when it is installed - and poly is definitely not a vapour "barrier" once it is installed.