Brad Diepholz talks about "Attic Ventilation-part 3"

Brad Diepholz talks about “Attic Ventilation-part 3”

Brad Diepholz found the following information.

When winter arrives and temperatures plunge you might think the movement of heated air would no longer cause problems in attics. This is not true! With seasonal changes the conditions just reverse.

Heat does not travel from an attic into the home. Instead heated indoor air travels from the home into the attic area. Moisture also travels into the attic during the winter months.

Furnace warmed air circulates through the house picking up water vapor generated by activities like cooking, showers, laundry and washing the dishes. The use of humidifiers during the winter months is common. This provides an abundant and continual source of moisture.

Keep in mind that the warmer the air is the greater it holds moisture. The problem is especially acute in homes with electric heating. Most of these homes were built before the 70’s using the advanced insulation materials and methods.

As a result most are air tight allowing minimal infiltration of outside air. Plus electric heat sources do not require air for combustion, so another common source of outdoor air has been eliminated.

The positive side of these super insulated homes is the greater energy efficiency.  Because of the cooler drier outdoor air is kept out the indoor air holds greater amount of moisture.

Problems arise when the warm moist air from the living area moves toward the attic where the air is cooler and drier. The moist air is drawn to the attic in two ways. The first is through a process called vapor diffusion. It is a process in which water vapor naturally travels from high humidity conditions to low humidity conditions.

The force of vapor diffusion is so great that moisture even travels through building materials such as dry wall or sheet rock. Vapor barriers for all their effectiveness cannot totally stop this process.

The second way will be explained on my next blog.

Typed by Brad Diepholz