Trapped air is an excellent insulator. As long as the air is NOT MOVING. The double pane windows in our home or a Thermos® bottle are two good examples of how trapped air acts as an insulator to keep what's inside warm or cold.

Wall insulation works the same way. As long as the air inside the insulation stays still and dry, the insulation works to its rated R-value. The result is a comfortable home.

But, an average 2,500 square foot home has more than 1/2 mile of cracks and crevices in the wall cavity and if the wind blows even a little (and it blows, on average, 8 mph across the US), air is forced into your home. Your heater or air conditioner will run more often to keep you comfortable, resulting in higher energy bills.

For over 20 years, DuPont™ Tyvek® has made millions of homes more energy efficient and more comfortable. DuPont™ Tyvek® reduces the movement of air into your home and also helps keep water (from driving rain, for example) out of your walls. DuPont™ Tyvek® can breathe too. That means that if moisture does get inside you walls DuPont™ Tyvek® lets it pass through to the outside. Helping to keep air and water out; letting moisture vapor pass through—it's the perfect way to keep you comfortable year round.

The average wall has 3.5 inches of insulation which, under ideal conditions, has an installed R-value of R-14. (Installed R-value includes the whole wall system, with studs, sheathing board, insulation and siding, and takes wind movement into account.) Tests have shown that, when outside air moves into the wall through any tiny crack or crevice resulting from normal construction practices, the insulation can lose up to 63% of its installed R-value. DuPont™ Tyvek® stops extra air from flowing into a wall.

Controlling the air coming into your walls is more important than adding more insulation to give you the performance and comfort you expect. Be sure to get the best insulating effectiveness and energy efficiency in your home.