How to manage moisture for a long-lasting home
Controlling moisture can make your home more energy-efficient, less costly to heat and cool, more comfortable, and prevent mold growth, according to the U.S. Department of Energy.
Moisture or water vapor moves in and out of a home in three ways:
- With air currents
- By diffusion through materials
- By heat transfer
Air movement accounts for about 98% of all water vapor movement because air naturally moves from high-pressure areas to lower pressure areas by the easiest path available, generally through any available hole or crack in the building envelope.
The other two driving forces -- diffusion through materials and heat transfer -- are much slower processes. Most common building materials slow moisture diffusion to a large degree, although they never stop it completely.
Building professionals and codes sometimes focus on managing moisture with a vapor barrier, but in some cases barriers can actually create moisture problems.
A vapor barrier manages water vapor diffusion, which is actually the smallest moisture source in buildings. Typically a vapor barrier is generally required on the inside of the wall and rain comes from the outside. When moisture does find its way inside a wall system, through a leak, a burst pipe or exposure during construction, a vapor barrier (especially if located at the wrong side of the wall) can prevent drying, creating ideal conditions for mold, rot and corrosion.
DuPont™ Tyvek® HomeWrap® weather barriers protect wall systems from water damage and air intrusion.
DuPont™ Tyvek® HomeWrap® is the original house wrap, incorporating unique material science that helps keep air and water out, while letting water vapor escape.
So while it’s highly effective at preventing bulk water intrusion, it’s also permeable, or breathable, to allow any water that does find its way into the wall system to find its way back out again as water vapor. This ability to allow unwanted moisture to escape can allow walls to dry more quickly to help protect against water damage from within. That’s an important added layer of protection that vapor barriers can’t provide.
Topics: Thermal Envelope