GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Audio Play Icon Headphones Icon Plus Icon Minus Icon Check Icon Print Icon Picture icon Single Arrow Icon Double Arrow Icon Hamburger Icon TV Icon Close Icon Sorted Hamburger/Search Icon

Community and Q&A

Vapor barrier at interior high humidity locations?

Ryan Magladry Ottawa, Ontario | Posted in General Questions on

Location: Ottawa, Ontario
Wall is 12″ thick R44:
2″ R8 EPS, zip system sheathing, 2×6 c/w R22 Rockwool, Intello+ interior smart vapour retarder, 2×4 c/w R14 Rockwool, interior finishing as specd

It is a limited vapour open wall in both directions.

I have a bathtub shower combo (acrylic base and acrylic surround), and a shower (acrylic base and tile over waterproof gypsum) against the exterior wall.

Given that these bathrooms will see elevated humidity should i add some 6 mil poly on the inside of the studs, between stud and the acrylic surround/waterpoof drywall?  In these 2 areas of the house the concentrated vapour/humidity will not be able to cross the poly?

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.

Replies

  1. User avatar GBA Editor
    Martin Holladay | | #1

    Ryan,
    This is a judgment call. If I were you, I would probably use interior polyethylene at the shower.

  2. User avatar
    Jon R | | #2

    My take is that an exhaust fan will create negative pressure and stop humid air/water ex-filtration (which can move a lot of moisture quickly). For the short (I assume) time that it's super humid, not much diffusion will occur - without poly, it can dry inward over many hours of normal humidity.

  3. Ryan Magladry Ottawa, Ontario | | #3

    Jon, I am using a balanced erv, so it wont have the moisture moving potential of a dedicated direct exhaust fan.

Log in or create an account to post an answer.

Community

Recent Questions and Replies

  • |
  • |
  • |
  • |