House Wrap Common Questions
How does House Wrap work?
House Wrap is made by a special non-woven fabric. This kind of non-woven fabric can effectively prevent water outside, but can discharge water vapor from inside the wall cavity. No one knows the technical principle of it. We can understand the non-woven internal structure like this: the fiber seam is larger than the diameter of air molecule and smaller than that of water molecule. So, only the water vapor can pass through the fiber seam. So the product is waterproof and breathable.Good house wrap is made by hot pressing technology. Some products are compounded by adhesive pressure. Although this product has certain permeability, it is not able to withstand high temperature. Under the high temperature of more than 45 degrees Celsius, the permeability of the product will soon go to 0, making the product lose its due permeability.
Will the installation of Waterproof Membrane make the house too tight?
In order to meet the gradually increasing requirements of energy efficiency, “building tight; ventilating right” seams the best way.
Mechanical ventilation is quite good for modern buildings with high tightness, but blower door testing on homes show that natural air exchange are also acceptable for houses with waterproof membranes.
Can a waterproof membrane become a true weatherproof layer?
Yes, the waterproof membrane is made of a unique material that prevents air and large amounts of water from penetration, while also discharging steam from inside the wall cavity.
Why should we use flashing tape above waterproof membrane?
At the laps of the waterproof membrane, the flashing tape can maintain the overall wind resistance and waterproof properties of the house structure.
Why do we use wooden strips to fix the air barrier?
Use wood as fastening facility has much more advantages than nails. Fix the Air Barrier with the wood strip, and pave the air barrier evenly before. The nail should penetrate through the wood strip the membrane and fixed onto the sheath wall board. It is better to use double sided butly tape between the membrane laps, which is right under the wooden strip. The butyl tape will seal all the seams between the nail and air barrier well. Finally, the use of flashing butyl tape upon the seam can enhance the waterproof performance of the product.
If I have installed an insulating layer, why should I need a building wrap?
Only when the air inside the wall cavity is dry can the R value of the insulation layer achieve the desired effect.With an average wind speed of 8 miles per hour, the air is easy to penetrate in from cracks and crevices inside the wall, even in new built houses. In this occasion, you may lose as much as 30% of your heating and cooling energy.The function of the building wrap is to effectively prevent airflow from entering the insulation, so that the insulation layer can work with the original R value.Not only that, but the building wrap can also prevent moisture from entering the walls, preventing house from being invaded by water and moisture problems.
Breathable Membrane application
Breathable Membrane is a kind of waterproof and windproof material for construction.
Breathable Membrane can be used in large commercial buildings behind stucco, stone, marble, metal panels, brick, granite and EIFS.The Breathable Membrane can effectively control the penetration problem of air and water, and discharge the water vapor inside the wall out to establish efficient building enclosure structure.
Is it necessary to remove old construction paper before using new breathable membrane?
No, it's not important to take the construction paper off before you install the new breathable membrane.However, damage areas that is invisible under construction paper must be carefully examined.And some old construction paper is not breathable,so if left on the wall, the breathable performance may lose some of its ability to distribute moisture to the outside.