How to calculate Soffit Vent Size – eHowSoffit Ventilation Size Requirements: Calculation

Vents in an attic contribute to the air quality in the attic.They allow for a continuous flow of air through the attic.It reduces condensation, extends the life of the roof and prevents mold.It helps lower the cost of air conditioning because it prevents heat from building up in the attic during the summer.Determine the correct number of soffit vents for your home.

Measure the length and width of your attic.To calculate the square footage of the attic, multiply these together.

You need 1 square foot of vent space for each 150 square feet of attic space if you divide the square footage by 150.Modern insulated homes need this ratio.If you have 3,000 square feet of attic space, this equates to 20 square Feet of Ventilation Needed.

An equal number of ridge vents would be required to divide the total ventilation needed by 2.You would need 10 square feet of vent space.