Two culprits

Two culprits cause most of the building-durability and health problems associated with improper attic ventilation –moisture and heat.

Moisture

Moisture is created inside a home each time someone takes a shower, cooks, does dishes, or does laundry. Moisture from these activities will almost always make its way to the attic. Moist air is drawn to the attic in two ways.

The first is through a process known as “vapor diffusion.” Water vapor naturally migrates from high to low humidity conditions –such as from the living space to the attic. The force of vapor diffusion is so great that moisture will even travel through sheet rock and vapor barriers designed to retard this process.

The second way is by air moving through openings cut into the building envelope. Such openings are common and include recessed lighting fixtures and attic hatches. If bathroom or kitchen fans are not properly ducted to the outside, the migration of moisture to the attic is more pronounced.