GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

WRB for a fiberboard wall assembly?

astroskidder | Posted in GBA Pro Help on

I’m building a house where the exterior walls have been sheathed with a bitumen treated structural fiberboard. I have two questions:

1. Should I tape the seams of the sheathing on the exterior side of the wall? If so, with what?

2. What is the best WRB for this type of wall assembly… building paper or Tyvek/Typar etc.?

Thanks.

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. GBA Editor
    Martin Holladay | | #1

    Daryl,
    Asphalt-impregnated fiberboard is hard to tape, as far as I know. I don't know of any tape that would work, but if I had to experiment, I would start by trying Siga Wigluv tape.

    Asphalt felt, building paper, or a plastic housewrap like Tyvek or Typar all work well as WRBs. The most important thing is getting the installation details right (lapping the WRB properly, and integrating the WRB with flashing at the window penetrations). These installation details matter more than the material you choose. For more information on this issue, see All About Water-Resistive Barriers.

  2. astroskidder | | #2

    Thanks Martin.

    We live in what can be a wet, hot climate and I'm concerned about vapour drive through the WRB on the exposed sunny sides of the cladding. I've read some reports about some housewraps actually making the matter worse by trapping water behind the WRB and causing problems with moisture sensitive assemblies like fiberboard, especially in cold climates (zone 6 for us).

  3. GBA Editor
    Martin Holladay | | #3

    Daryl,
    If you are worried about inward solar vapor drive:
    (a) It's best to avoid so-called reservoir claddings.
    (b) Make sure that your walls don't include interior polyethylene.
    (c) Include a ventilated rainscreen gap between your siding and the WRB.

    For more information on this issue, see When Sunshine Drives Moisture Into Walls.

Log in or create an account to post an answer.

Community

Recent Questions and Replies

  • |
  • |
  • |
  • |