If you are a homeowner, understanding what housewrap is and its purpose is important if you are looking into buying a new construction home. Homebuilders can benefit from understanding issues that are commonly found with housewrap during an inspection to work diligently from facing those same errors.

Housewrap is a sheathing material, usually made from plastic or spun-fiber polyethylene, that serves to protect the building envelope from water intrusion. Housewrap also always water vapor, or humid air, to escape the interior; its purpose is to help protect a home from water damage and mold.

The most recognized branded material for house wrap is Tyvek®, which is a synthetic housewrap material made of flash-spun, high-density polyethylene and is manufactured by DuPont. Tyvek® is so widely used because it resists air and moisture intrusion better than many others available on the market.

Other types of housewrap could include those made from:

• Micro-perforated cross-lapped films
• Films laminated on spun-bond and non-woven material
• Films laminated to polypropylene-woven material
• Asphalt-impregnated paper (commonly known as tar paper)

Housewrap has many benefits, primarily its protection from water-based environmental factors. It is widely used in areas heavily known for humidity and rainfall to help protect the framing of the house. Because it allows vapor to escape but not enter, homes with housewrap are better protected against conditions ideal for mold growth. With these being the primary purposes for using housewrap, they also provide a third benefit—improved insulation of the home by restricting airflow.

It is important to note that even with some restriction in vapor movement, housewrap is not a vapor retarder. It must be installed with the proper lapping to ensure its water intrusion prevention capabilities are put to best effort. Housewrapping also cannot be exposed to the elements for too long. The inspection should occur shortly after installation and siding, or cladding installed over it to ensure the housewrap does not become damaged.

Before calling out a home or building inspector, check for these common mistakes:

• Housewrap is supposed to be installed before the windows and doors are installed.
• Installation should have been conducted as recommended by the manufacture to ensure the housewrap functions as it the manufacture designed it to.
• The upper layers of housewrap should overlap the lower layers—this avoids improper channeling of water.
• Vertical joints should be overlapped by a minimum of 6 inches but no more than 12 inches.
• Horizontal joints should be overlapped by at minimum of 6 inches.
• Proper joints require covering with tape specifically designed to be used in coordination with housewrap.
• When installing the housewrap, staples or roofing nails should be used and should be a minimum of 1 inch in length. They should also be spaced 12-18 inches on-center.
• There should be a drainage provision installed at the bottom of all external siding or cladding material.
• The foundation joint and the sill plate need to be covered by housewrap.

By double checking for these common errors, homebuilders can avoid delays in their build timeline and prevent an increase in costs due to the reinstallation and additional work hours. Home inspectors  and homebuyers can also train themselves to look for these key components to ensure the housewrap was properly installed and will work as intended.