August 2010
Do You Mind If I Vent?
Attic ventilation is important but often overlooked

The insulation in your home's attic (and hopefully there's enough) keeps blistering summer heat out of the living space. Proper attic ventilation helps insulation work even better.

On a typical summer day, attic temperatures may easily reach 130 degrees or higher. That's while you're trying to maintain a comfortable 78 degrees below. The trapped air inside insulation materials provides a barrier against heat movement. But some of the heat still makes its way inside.

One way to help the insulation is to decrease the temperature difference between the hot attic and cool living space. Attic vents do just that.

You don't need fancy vents that twirl in the wind or expensive electric-powered models to do the job. Plain, economical aluminum vents, if properly placed and installed, will do a good job of reducing attic temperatures. Although most homes have eave vents, additional vents are needed the entire length of the roof for proper ventilation.

Electric-powered vents may actually consume more electricity than they save, especially if the thermostat that regulates them is set too low.

To get proper airflow, attic vents should be placed at the highest and lowest parts of the attic - typically the soffits and the roof ridge. Soffits are the area under the roof overhang perpendicular to the outside walls.

Since warmer air rises, the combination of high and low vents accommodates natural convection. As hot air rises and exits through the ridge vents, cooler air through the low soffit vents will replace it.

Both ridge and soffit vents come in a continuous strip that provides the best results. But, installing them on existing homes may be difficult. Using a sufficient number of individual vents may be a better solution.

Once summer is over, attic vents still have a job to do. In the winter, they keep excess moisture from accumulating when water vapor from the living space contacts cooler surfaces in the unconditioned attic. That means don't cover them with plastic when the weather gets cooler!

Contact a roofer or insulation company to install attic ventilation. As with any contractor, get references and check them thoroughly before hiring them to work on your home.