Wall Sheathing Membrane

Sheathing membrane (traditionally referred to as sheathing paper) should be water resistant but vapour permeable. New materials, such as spunbonded polyolefins and poly-propylenes, are being used today that are not paper products. The sheathing membrane's function is to provide a second barrier to the entry of any wind and rain that might penetrate the cladding. It is also intended to direct water, which does penetrate the cladding, over the flashing at the base of the wall. It must be permeable enough, however, to permit any water vapour to escape from the interior that may penetrate imperfections in the air and vapour barriers. One layer of sheathing membrane is generally used over wall sheathing and may be applied horizontally or vertically with 4 in. (100 mm) laps at the joints. At horizontal flashings, the upper sheet should be lapped over the lower sheet to direct moisture outward.

Where wall sheathing is not used, two layers of sheathing membrane are needed unless a large panel siding such as plywood is used. Both layers are applied vertically, with the joints lapped 4 in. (100 mm) at the studs. Both layers are stapled to the framing members, the top layer with staples spaced every 6 in. (150 mm) along the edges of the sheet to hold it securely in place.

Wood Working for Amateur Craftsman

Wood Working for Amateur Craftsman

THIS book is one of the series of Handbooks on industrial subjects being published by the Popular Mechanics Company. Like Popular Mechanics Magazine, and like the other books in this series, it is written so you can understand it. The purpose of Popular Mechanics Handbooks is to supply a growing demand for high-class, up-to-date and accurate text-books, suitable for home study as well as for class use, on all mechanical subjects. The textand illustrations, in each instance, have been prepared expressly for this series by well known experts, and revised by the editor of Popular Mechanics.

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