Housewrap vs building paper
I am building an energy efficient house in Victoria, British Columbia. The wall system is 2×6 construction covered with 1 1/2″ XPS for a nominal R-27. The XPS will be calked at the perimeter and all joints taped to form the air barrier. In my municipality the Code requires that the the walls have a rain screen (it is actually a 1/2″ capillary break) and two planes of protection against water intrusion. The siding material constitutes the first plane of protection. The second plane of protection is either housewrap (such as Tyvek) or building paper is against the exterior of the sheathing (in my case the XPS).
My question is which material is superior as this second plane of protection against water? My framer and exterior finish carpenter both feel that building paper is better as it is less easily damaged and will tend to seal around nail holes. The local building official, on the other hand, feels that housewrap is the superior product.
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Replies
Ross,
Either product works fine. Installation details are far more critical than which product you choose.
For more information on all the options when choosing a water-resistive barrier (WRB) -- including housewrap, building paper, and asphalt felt -- see All About Water-Resistive Barriers.
How are you attaching your siding? Are you running vertical strapping at stud locations and fastening to the studs? If that's the case I'd probably go with housewrap over paper, only because I think it will hold its shape better over time with such infrequent fastening. I'm assuming you'd run the housewrap over the foam and then hold it in place with the strapping.
Hi Dan,
Vertical strapping (1/2"x2" PT ply) will be every 8" to form the rain screen (Code in this area).