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Gable Vents

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August 1, 2023 at 12:02 a.m.

alextolle

Lyn in Pennsylvania asked the following:

Do I need gable vents if I have a top vent? The house was built in the mid 70s and upstairs is always hot in summer and cold in winter. New siding and roof installed three years ago. New AC unit was installed this month and was told we needed side vents if upstairs is to be cooler. Getting mixed advice.

August 1, 2023 at 12:05 a.m.

alextolle

Below is what our roofing expert Marty from Go Roof Tune Up had to say in response to your question:

You need PROPER VENTING.

Your attic needs to breathe in cool air from the lower sections of the roof (eave) and exhaust the hot air at the top (ridge, gable). Adding venting at the upper section of the attic will not help properly ventilate the attic unless it is along with adding the amount of venting to the lower section.

Most venting professionals recommend a 50% upper and 50% lower mix with a total net free air space of at least 1sq in to 300 sq in. Some building departments require 1/150. But always 50% exhaust, 50% intake.

Many companies that make attic ventilation products have very helpful calculators on their website.

Marty

August 1, 2023 at 2:48 p.m.

alextolle

John Kenney of Cotney Consulting Group says:

Lyn in PA:

For an attic to vent correctly, you need a vent that pulls the air and another venting source that allows the air to enter and pull through, such as a roof ridge vent and soffit vent combination. This allows the air to flow freely and exhaust out through the ridge or roof vent.

A gable vent is usually a side power-operated vent that pulls air through an attic. They do not work and can be counter-productive with rooftop vents. Adding vents at the soffit would be a better choice to pull the air up through the power-operated rooftop vent or ridge vent.