How to Check for Proper Ventilation in the Attic & Soffits

Look around the house for signs of too little ventilation. Peeling outside paint, mold under the soffits and quickly aging asphalt roof shingles are prominent symptoms of a lack of ventilation.

Check the attic to determine whether it has a vapor barrier across the underneath of the roof. Measure the square footage of each ventilation area and add up the total. Check to see whether the vents have screens or other coverings over them. Remove any insulation that might have blown over the vents. For every 300 square feet of attic space with a vapor barrier, you should have a minimum of one square foot of ventilation vents. If you don't have a vapor barrier, it changes to 150 square feet to one. If the vents are screened over, add at least 25 percent to the square footage of vent space you should have.

Note the placement of the vents, whether high in the attic or low along the soffits, or a mixture. If the bulk of the vents are either high or low, you probably have poor circulation throughout the attic. Too few low vents means not enough fresh air is coming in, and too few high vents means not enough hot air is escaping.