What Your Customers Want to Know about Attic Ventilation

Let’s answer these frequently asked attic ventilation questions.

By Andy Swan, Roof Saver.

We get attic ventilation questions from inquiring minds that seem to repeat over time – the questions, not the minds. So, let’s share the wealth of knowledge.

I have a continuous ridge vent and soffit vents installed. Is it a good idea to also have gable vents? No. The vent system was likely converted from a gable end exhaust to ridge vents at one time. The best practice is to seal the gable end vents from the inside of the attic using OSB or plywood to prevent the vent system from short-circuiting where air enters the gable and exhausts at the ridge. The International Residential code requires a minimum of three feet of vertical distance from the level of the intake to the level of the exhaust vents.

I live in a warm climate area so moisture condensation is not common. Is attic ventilation needed here? Yes. The obvious benefit of an attic vent system in your case is to reduce heat buildup in the attic. You are likely running the air conditioning more frequently because of the high attic temperature. A proper attic vent system allows the excess heat to escape the attic. The less obvious benefit is to vent excess moisture from the attic to deter the growth of mold.

How does an attic ventilation system prevent ice dams? Ice dams form when snow on the roof melts and the runoff then freezes at the edge of the roof. Eventually you can have heavy ice coverage that blocks water from flowing off the roof. The water may backup and leak into the attic space.

To solve this problem, you should first check the attic insulation to ensure proper coverage inside the entire attic. Once you are confident that the insulation is adequate, check the attic vent system to ensure you have at least one square foot of attic ventilation per 300 square feet of attic space. Fifty to sixty percent of the total net free area of the vent system should be intake at the soffit and 40 -50% is installed as exhaust at the ridge. When the vent system is working properly, the air inside the attic should be about as cold as the exterior air.

Andy Swan is president of Blocksom and Co., manufacturer of Roof Saver Ridge Vent. For more information on Roof Saver visit www.roofsaver.com<