Housewrap with rigid insulation
cjm5199
| Posted in Green Building Techniques on
I am in the process of building a home with 3/8 zip sheathing, with two layers of rigid poly iso on the exterior of the sheathing. I have read “Musings of an Energy Nerd – How to Install Rigid Foam Sheathing and it discussed the placement of the WRB. I have installed windows as “outies.” Two questions 1. Do I need a house wrap product on the exterior of the foam or will the zip sheathing suffice? 2. If I do need a house wrap how are people installing it over rigid foam? Fastening to the exterior of the vertical furring strips or sandwiching between the furring strips and the foam board?
Thanks for your help!
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
Christopher,
Every house needs a water-resistive barrier (WRB). In your case, you can choose to make the Zip sheathing the WRB, or (if you prefer) you can add housewrap and the housewrap can be your WRB. Either way will work, but you need to know which layer is your WRB -- because all of your flashing has to be integrated with your WRB.
For more information on this issue, see All About Water-Resistive Barriers.
Although Zip sheathing can work as a WRB, some people prefer to add housewrap, since it is easier to integrate housewrap with your flashing than to integrate Zip sheathing with your flashing. (Housewrap can be lapped).
If you want to include housewrap, you have to decide where to put it. See this article: Where Does the Housewrap Go?
Q. "If I do need a housewrap, how are people installing it over rigid foam? Fastening to the exterior of the vertical furring strips or sandwiching between the furring strips and the foam board?"
A. Sandwiching it between the furring strips and the foam board.