How Many Soffit Vents Are Necessary?

Red eaves in the foreground, white eaves in the background.

Soffit vents are vital in keeping air flowing throughout your attic space. Even if you have vents in your roof, you still need to have soffit vents to allow the air to circulate naturally. There are a number of different types of vents to choose from, so getting the ones to suit you should not be difficult, although you will still need to work out how many to purchase. This article provides some guidelines to help you make that decision.

Building Regulations

The amount of soffit ventilation you need will depend upon building regulations. There are strict rules about exactly how many soffits, also called air intake vents, are required and how far apart they must be. Check your local authority for the specific regulations in your area and get a list of requirements. You could also check with local building inspectors once the soffits have been fitted to make sure you did it right.

Measure Your Attic

The building requirements will probably tell you to place a certain number of soffit vents per square foot of ceiling space. For example, you might have to place one soffit vent and one other kind of vent for each 150 sq. foot of ceiling. Therefore, you will probably have to measure the area of your attic to find out how many soffit vents you will need.