New house construction proceeds in stages. After the floor joists and subfloor are in place, the contractor will frame the interior and exterior wall of the house and install boxing on the exterior walls. Eventually, siding will cover the boxing, but most siding, unless it’s masonry, isn’t airtight. Cold winds, rain or snow may blow up and under the siding, reducing the energy efficiency in the home. To remedy this, most contractors install house wrap over the boxing before hanging the siding. Tyvek is a brand name of house wrap manufactured by DuPont.
House wrap reduces heating and cooling costs by reducing drafts that might otherwise blow through gaps in the siding and into the home around windows, outlets and switches. The United States Department of Energy estimates that as much as 30 percent of the cost to heat and cool a house comes from air leaks.
Tyvek HomeWrap repels water and restricts airflow. The house wrap is available in rolls that are 9 feet wide and 150 feet long. Although standard house walls are only 8 feet high, the house wrap must also cover the sill plate between the foundation and the bottom wall plate. DuPont manufactures special tape with which to seal the edges of the house wrap. Failure to use the exact products specified by DuPont might void the product’s limited warranty.
Installing house wrap is much like wrapping a huge birthday present. The contractor positions the end of the house wrap vertically at one corner of the home and rolls it out, keeping the wrap level, smoothing it and stapling it to the boxing. The wrap goes around the entire house, covering doors, windows and other openings. If the house has a second story, or the walls are taller than one width of house wrap covers, the upper section of wrap must overlap the lower section to ensure adequate water shedding. All seams must be sealed with house wrap tape.
Windows and Doors
The efficiency of house wrap depends upon the elimination of drafts. Windows and doors are more prone to drafts, because gaps remain between the door or window frame and the wall frame. Although most builders insulate this gap, it’s still a weak spot. To remedy this, the builder cuts the house wrap that covers a door or window in an “X” shape and pulls the triangular wrap sections snugly inside the door or window frame, stapling and taping them in place.
- Photo Credit Ryan McVay/Photodisc/Getty Images