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I had a new roof installed on my house a couple of years ago. The new roof has ridge vent along the peak of the main roof as well as where this gable vent is. I was reading on an unrelated topic that you should close off gable vents if you have ridge vents and if you have continuous soffit vents around the house (I do).

The vent is about 2' in diameter overall. Do I do any harm leaving it open, or should I close it off? It's the only gable vent on the house. Also, other than thin plywood, any thoughts on sealing it off from the outside? I am getting new insulation blown in and would rather not climb over or through it to get to the vent from the attic space. Also, I won't have a chance to get up there before the new insulation goes in.

isherwood
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TBoneHuff1970
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The ridge vent is the exhaust in this passive system; the soffit is the intake. Yes, the gable vent on the vertical wall need to be close or this will short circuit the system.

You need to make sure that the soffit vents are not blocked by insulation in the attic and that the area underneath the soffit vents are indeed providing air. Vinyl or aluminum soffits should be mounted directly under the roof rafters, though you sometimes see covers tacked up to wood soffits. The wood soffit needs cut out behind these covers, and that is always not the case. Many times, lazy workers cut much smaller holes behind these covers.

You should calculate the square inches of exhaust area and compare that to the square inches of intake area. The intake area must be greater than the exhaust area or the system will be starved and will attempt to pull air in along other routes, such as light fixtures etc.

Evil Elf
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