0 Helpful?

WRB for a fiberboard wall assembly?

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.

Asked by Daryl Ross
Posted Jul 1, 2014 12:33 AM ET
Edited Jul 1, 2014 7:32 AM ET

Tags:

3 Answers

Select your preferred way to display the comments and click "Save settings" to activate your changes.
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.

Answered by Martin Holladay
Posted Jul 1, 2014 7:55 AM ET

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).

Answered by Daryl Ross
Posted Jul 1, 2014 10:49 AM ET

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.

Answered by Martin Holladay
Posted Jul 1, 2014 10:58 AM ET

Other Questions in GBA Pro help

Dense Packing Cellulose with the Krendl 425

In Energy efficiency and durability | Asked by Joe Duchek | May 23, 17

Average lighting, appliance and plug loads for PV sizing?

In Mechanicals | Asked by Burke Stoller | May 23, 17

Opinions on my exterior options

In Energy efficiency and durability | Asked by Jeremy Archer | May 15, 17

Sealing PT sill plate to concrete slab ?

In Energy efficiency and durability | Asked by Mark McFarlane | May 20, 17

How to deal with duct-work that installed in unconditioned attic and a powered attic ventilator?

In Energy efficiency and durability | Asked by TedLiu | May 22, 17
Register for a free account and join the conversation


Get a free account and join the conversation!
Become a GBA PRO!