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Housewrap keeps a home dry and enery-efficient no matter what kind of exterior finish is applied. Photo courtesy of DuPont Tyvek,
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By Deborah L. O'Mara
When housewrap is installed properly, your customers are sure to stay warm, dry and comfortable. But just as important, the wall assembly of the house itself will be dry, which is crucial to its longevity.
However, there are some critical steps to proper installation—essential to how well it performs. The best housewrap in the world can't do its job unless it is applied properly.
Housewrap is made of fine, high-density polyethylene fibers that are strong and vapor-permeable, yet water-, chemical-, puncture-, tear- and abrasion-resistant. Applied to the exterior of the structure, it increases air and water resistance and lowers heating and cooling costs while providing better protection against water and moisture intrusion. The unique qualities of the products on the market stop air flow through wall cavities, help hold out bulk water and wind-driven rain, and allow moisture vapor to escape from inside walls.
For the contractor, housewrap serves double-duty. It helps protect the work site and structure early in the construction stages, and ultimately provides the homeowner with a more energy-efficient home that is better protected from damage by trapped moisture.
"You want to prevent the elements from coming in as early as possible in the construction stage," says Kirk Moffitt, president of Moffitt Construction in Evanston, Ill. Kirk has been in the remodeling business for some 13 years with his brother Dave, vice president of operations. The firm specializes in kitchens, baths and additions. "Housewrap is a barrier for the overall structure, and it keeps workers dry during the time when the structure is open, which can be two to three months," says Kirk.
In addition to keeping the raw elements out, housewrap and other residential wall sheathing provide moisture and mold resistance, increasingly important to his customers, says Mike Speciale, owner of Speciale Homes in Austin, Texas.
To begin with, Kirk adds, "the tighter the installation, the better." He says the product must be installed taut with no air barriers behind it or loose or flapping areas. He offers these other words of wisdom:
- Keep the housewrap smooth and straight throughout the installation.
- Overlap each layer to the outside as you go up so that moisture will drain to the outside.
- Overlap the seams of the housewrap at least one foot and secure the seams tightly with tape designed specifically for the sheathing.
- To install around windows, cut an "I" in the window opening. The top of the I-cut is horizontal with the top window rough opening. The vertical cut is about ¾ of the window opening height. The bottom of the I-cut then goes into the bottom corners of the roughed-in window opening. Side and bottom flaps are folded to the inside of the framed-in rough window opening and fastened about every six inches. The top and bottom corners of the window opening are then flashed from front to back to create an air seal. (The cut edges of the housewrap in the bottom corners of the window opening are taped to prevent water infiltration.
- Beware of tears in the product; they lessen its effectiveness as a weather barrier and may allow wind or moisture to penetrate.
- Apply the sheathing with staples or button cap nails.
- Make use of different sizes; it generally comes in four-, nine- and 10-foot rolls.
Properly installed housewrap takes an eye to technique, but the results pay off in years of comfort, energy efficiency and durability.
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