House Wrap Under Roof Sheathing

In general a sheathing wrap should have a perm rating of at least 5 to enable walls to dry out in a reasonable period of time should they get wet.

House wrap under roof sheathing.

It is literally wrapped around a building cut out around windows and doors and taped at the seams. Traditional sheathing wraps such as asphalt felt and grade d building paper used under stucco both measure about 5 perms. Where you ll often see plywood used instead of osb is in roof sheathing where the risks of moisture and leaks are greater. That keeps drafts from reaching your insulation and prevents heated and cooled air from seeping out through the walls.

In theory the sheathing on your home should never get wet as long as the proper preparations are made when siding the home flashing house wrap j channel caulk etc. The reason for this is the housewrap manufacterers instructions call out their own product not their competitors. You can find a complete library of technical documents for the zip system at this link. At the same time the sheathing wrap must be permeable enough to allow drying to the building s exterior if the framing or sheathing should get wet.

Plastic housewraps range from around 5 to over 50 perms. House wrap behind a building s siding is an excellent secondary defense against the weather. Seal all seams with a special tape provided by the house wrap manufacturer. When used to slow winds its job is to seal gaps and leaks in the osb panels or plywood sheathing that makes up your home s exterior walls.

The other wrinkle is that when using zip sheathing very few manufactures include instructions for installation on that type of sheathing. Depending on how it s hung house wrap can either act as a moisture or wind barrier. Wrap the fabric around the edges of windows. It just a matter of careful detailing especially around doors windows and other joints prone to leakage.

A house built well with wood sheathing covered with asphalt paper or plastic house wrap can perform as well as one with zip sheathing. Most house wraps are weather resistant barriers wrbs that aim to prevent air and moisture infiltration to the wall system while protecting the sheathing. In this post we compared barricade wrap plus tyvek homewrap homeguard house wrap certainteed certawrap and the zip system. The homes i built then still look brand new today.

The primary goal of a sheathing wrap or housewrap is to protect a building s structural components from water. I ve been using hardie siding in the texas heat for over 10 years. Hardiewrap weather barrier is installed over the sheathing beneath the exterior siding to reduce water and air infiltration. Work from the bottom up overlapping the lower courses.

General recommendations that usually apply to fabric type house wrap include.