Attics are often overlooked and may be viewed by homeowners as just another place to store excess boxes of clothes and decorations. This is a mistake because, if not properly ventilated, attic space can negatively affect energy bills, roofing shingles, insulation and indoor air quality.
When the sun hits the roof of a home during the summer months, the heat is absorbed into the attic. Without proper ventilation, the heat can radiate into the living space below, causing air conditioners, fans, refrigerators and other appliances to work harder. In this scenario, effective ventilation cools the home and can lead to reduced energy bills.
Proper ventilation is also important in the winter, when moisture is a primary concern. The daily activities of an average family of four generate approximately two to four gallons of water vapor. This vapor rises to the colder and dryer attic where it can condense if not properly vented, leading to the dampening of the attic insulation. Damp insulation causes wood rot, mold, and mildew, leading to poor indoor air quality in the rest of the home.
Poor ventilation can also affect the exterior of a home, in the winter, warm areas on a roof can lead to snow melt and the formation of ice dams. Ice Dams are formed in colder climates when heat bypasses insulation through light fixtures or exhaust systems, creating warm areas on the roof, melting an area of snow. This leads to the melted snow flowing down the roof until it hits a colder spot, where it refreezes and causes a back-up of ice on certain parts of the roof. Proper attic ventilation can remove the heated air from the attic and prevent ice damming in the winter before it becomes a hazard.
Excessive moisture and heat build-up can also cause the shingles and decking of your roof to deteriorate prematurely. Proper ventilation of the attic space reduces the surface temperature of the roof, eliminating moisture that can eat away at your home.
The best way to achieve balanced ventilation in your attic is to create continuous airflow along the entire underside of the roof sheathing. The flow of air from the lower portion to the upper portion operates like a chimney and is referred to as the “stack effect.”
Here are a few tips for avoiding common mistakes that homeowners, and even contractors, might make when installing a ventilations system:
- Check that intake vents are not covered with insulation or painted closed
- Insert attic insulation baffles in soffit of intake vents
- Use only one type of exhaust vents on the same roof of a common attic
Attic ventilation is green. A balanced ventilation system requires no energy to run and can help reduce bills and damage to your home. Be sure to ask your contractor about proper ventilation before sealing your attic structure. Visit www.ravcoalition.org for more information about attic ventilation.