House Wrap: Air Sealing and Protection From the Elements
Use house wrap when framing a home to block out moisture and unwanted air.
When you go out in bad weather, you wear a jacket to protect yourself from rain, wind and other elements. A home should be protected in the same fashion. Without a protective barrier, the home can get wet, which can lead to wood rot and mold growth.
Is there a better way to protect a home from these elements?
Using a house wrap during the framing stage of construction will prevent moisture from entering the home. This will protect the house from rotting and from developing mold or fungus. Additionally, air infiltration through the framed walls will be blocked.
The "best practice" for protecting your home from wind and water while allowing it to "breathe" is to install a layer of "house wrap" made of a thin layer of spun-bonded polyethylene.
Here's how to do it:
- Start at a corner, but make sure you have 2 to 3 feet of house wrap to overlap the corner. Wrap it around the corner and continue nailing or stapling as you move. Wrap the entire building, including door and window openings.
- Use button nails or minimum 1-inch staples to fasten the house wrap every 12 to 18 inches along the vertical studs.
- Make an inverted "y" cut, or "martini glass cut," over the window openings. Fold the flaps in through the opening of the two sides and the sill and fasten them inside.
Many builders do not install a drainage plane at all. The builders who do often install "building paper," a sheet of asphalt-impregnated felt paper, to protect the house from exterior water penetration. Unlike house wrap, however, building paper doesn't effectively reduce air infiltration because it has many seams, while house wrap is a continuous sheet with minimal overlaps.
House wrap produces a breathable, weather-resistant barrier that will reduce energy costs and prevent wind-driven rain from entering the walls of a home.