subject: Which Moisture Barrier's Right For Your Vinyl Siding Project? [print this page] Although it will provide some supplemental protection to your house from rain and snow, vinyl siding is not designed to be a watertight barrier to the weather. Vinyl siding is instead designed to be an exterior shell that allows the materials underneath to breathe. For that reason, it's particularly important to choose a house wrap that will protect your home from the elements and keep wind and water from sneaking inside, where it can cause discomfort and damage.
Why a Moisture Barrier under Vinyl Siding?
According to the Vinyl Siding Institute, a proper weather resistant barrier beneath your vinyl siding sheds moisture and diverts water away from your home. The barrier system includes your vinyl siding, flashing at key wall openings, the weather-resistant wrapping, and sheathing--which is the wood sheets encasing your home. What that barrier must have is typically determined by your local building codes.
How to Wrap a House for Vinyl Siding
House wraps come in large rolls that are unfurled over the exterior sheathing of a home and then stapled to the wood before vinyl siding installation. The wrap is rolled out prior to the installation of doors and windows, and the material is rolled over these openings and then cut from the inside and pulled into the interior walls and stapled tight. It's not difficult to install the wrapping on a home under construction, but it will take two people working together to keep the wrapping tight and flat.
Here are some things to keep in mind if you are installing your own house wrap:
Do not leave house wrap exposed to the sunlight very long; most house wraps degrade when left in the sun.
Read the installation instructions; your house wrap may have an inside and outside face, and the wrap won't perform properly if it's installed backwards. Seams must be taped with special adhesives, not ordinary duct tape.
Wraps and flashing around windows and doors must be overlapped by pieces above it, like roofing shingles.
Avoid wrinkles when installing housewrap.
There are about seven major brands of housewrap on the market, but since there is no uniform testing standards, it's difficult to determine which one is better. Check with your local building department first to see if they have standards for house wraps; some are thicker than others, and there may be different rules about how long the wrap should be applied.
