The Purpose of Installing House Wrap
HOUSE WRAP is a dual function weather barrier.The HOUSE WRAP can not only reduce the drafts in the room, but also prevent the rainwater from penetrating into the wall and play a role of drainage.However, the HOUSE WRAP is not a vapor barrier. The uniqueness of HOUSE WRAP lies in that it can not only prevent rain water from penetrating, but also allow water vapor to be discharged out.HOUSE WRAP allows moisture from the interior to escape to the outside, while preventing rain from the outside from entering inside. Then where can be the HOUSE WRAP applied?Almost all the houses can use it after the sheath wall is completed.
To understand WATERPROOF MEMBRANE, we shall take a look at the following words:
Air permeability: the amount of air allowed to pass through (the coefficient of wind resistance)
Water vapor transmission: the amount of water vapor allowed to pass through ( the amount of water vapor which can pass through the membrane in a certain time.)
Water resistance: property that prevents external rainwater from penetrating
Moisture proof: the property of preventing moisture and water absorption
Durability: tear resistance
Importance of proper installation of BREATHABLE MEMBRANE:
For any kind of BREATHABLE MEMBRANE, the improper installation means the membrane will not work properly. And sometimes, improper installation will lead to harsh problems.
In general, BREATHABLE MEMBRANE is installed as an air barrier. In fact, BREATHABLE MEMBRANE will absorb water. If the installation method is not able to allow water vapor to pass through, then BREATHABLE MEMBRANE will cause serious water problems.
The installation tips of waterproof membrane
Follow the manufacturer's installation instructions
Windows and doors should be installed after the installation of waterproof membrane
Correct lap is the key ------ the upper WATERPROOF MEMBRANE should be installed outside the lower one.
Horizontal lap at least 6 inches
Vertical lap 6-12 inches (depending the strength of wind and rain in this area)
Install the wooden strip above the lap joint, and use thermal insulation screws to fix the strips.
Install drainage at the bottom of the cladding
Extend house wrap over the sill plate and foundation joint
How does water get into walls?
How does water get into walls?High humidity and extreme temperatures cause vapor diffusion.
Water vapor flows from a warm place to a cold place (into the wall cavity) and then condenses on a colder surface.When there are wind and rain, the rain will come into the gaps between the cladding, lap joints, utility cut-outs, electrical outlets, nail holes, etc.The wind blowing into the building creates a negative pressure within the wall structure, which siphons water into the wall.There are also water-absorbing cladding, such as brick, stone and stucco, which are porous structures.Behind the cladding, every house should have a drainage system, which can block the bulk rain water and form a second protective layer of the house and this MEMBRANE ROOF has the unique moisture control performance.