Attic Ventilation Help

Ventilation Ratio

• Whether you are having a problem with inconsistent temperatures and humidity levels in your home, or your attic is suffering from leaks or wind-damage, an improper ventilation ratio could be to blame. Ventilation ratio refers to the square-footage of ventilation an attic has in relation to the overall square-footage of an attic's ceiling space. When a ventilation ratio is too low, hot, humid air has a more difficult time escaping homes, while cold dry air has a more difficult time entering homes. When a ventilation ratio is too high, the excessive open space can encourage leaks and allows wind gusts to have a more severe impact on rooftops. According to Servicemagic.com, a proper ventilation ratio for an attic is typically around 1 to 300, which means an attic should have 1 square foot of ventilation for every 300 square feet of ceiling. However, this is just an estimated figure, so you should always consult with a professional to determine your home's specific ventilation requirements.

Non-Mechanical Vents

• If you know your home needs attic ventilation, but you are unsure what type of system to install, consider the two main varieties: non-mechanical and mechanical. Non-mechanical vents utilize slats or screens to allow air to flow freely in and out of attics. Some of the most common non-mechanical vents include ridge vents, soffit vents and gable vents. A ridge vent is a long section of vent that runs along the entire top peak of a home's roof. People commonly use them in conjunction with soffit vents, which run along the undersides of an attic's overhanging edges. While ridge vents are ideal for allowing hot air to escape, soffit vents are ideal for allowing cool air to enter. Gable vents are compact non-mechanical vents that homeowners install on the sides of attic walls, particularly where the walls peak.

Mechanical Vents

• Also known as ventilators, mechanical vents suck air in and out of attics using turbines or fans. Homeowners can install mechanical vents within attic walls, within the roof or existing non-mechanical gable vents. While some types of mechanical vents, known as non-powered vents, utilize the wind to turn their fans and turbines for generating suction, the most effective mechanical vents, known as powered vents, turn their fans and turbines with motors.

Insulation Advice

• Installing insulation on the underside of a roof, between attic rafters, can cut down on ventilation. However, instead of removing or avoiding such insulation, you can increase circulation by installing rafter vents underneath it. Rafter vents are long, plastic panels, which have ridges for guiding air beneath roof insulation.