Tyvek is the brand name for a product made by DuPont that helps to protect a home against wind and rain. During the construction process, workers apply it beneath the home's exterior cladding, such as siding, brick or wood. In effect, it helps to seal the completed home against outside air moisture. DuPont claims that homes wrapped in it often have lower overall energy costs.
Tyvek does its work because of its construction and materials. According to DuPont, it consists of a spun-bonded olefin (synthetic fiber) material made by combining another material, polyethylene, to it. Polyethylene itself is a synthetic plastic resin often seen in packaging and electrical insulation. DuPont makes Tyvek by taking polyethylene and olefin fiber and bonding them together through a heat-and-pressure process, creating an effective air barrier wrap.
Because olefin fiber and polyethylene are non-woven, they block the passage of excess water from a home's exterior into its interior walls. That can make Tyvek especially helpful during driving rainstorms, for example. In addition, moisture vapor in a home's wall system is able to pass through Tyvek from its back side, helping to keep interior walls dry. Keeping water out while letting moisture vapor leave is a particular strength of Tyvek home wrap.
DuPont states that Tyvek is able to reduce total heating and cooling costs of a home wrapped in it. That's because it serves as a type of thermal insulating material, preventing warm or cool air, depending on the season, from entering a home. It also keeps warm or cool air, again depending on the season, from leaving a home. Air between the exterior cladding and the Tyvek works as a thermal barrier.
Tyvek always goes over exterior wood-based wall sheathing, usually plywood of some sort. However, it won't work if it doesn't connect to all parts of what's known as a home's air barrier system. Foundation walls, the space around windows and doors, and anything else that penetrates walls or ceilings are all part of the air barrier system. This connection is necessary for Tyvek to be the principal component for airtightness in a home.
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