Number Of Roof Vents Required

As a general rule your roof needs 1 square foot of vent area for every 150 square feet of attic space.

Number of roof vents required.

Calculate the square footage of your attic. In our case the required 4 vents for the 1200 sq ft house multiply the 144 cubic inches by 4 576 cubic inches. Measure the length and width of the attic space using a tape measure. Divide the vent s nfa into 1 100 to yield the number of vents needed either in linear feet or units pieces.

Next divide that number by 2. Embershield closeable soffit vents. Eac 16x8 metal soffit vents. A normal metal pot vent produces only 50 squares inches of free net area.

Foot of ventilation for every 150 sq. Near ridge of the roof. They should be divided equally between inlet and outlet vents and they can be used in any combination that will work with your roof s design. Multiple these two.

Eac 16x4 metal soffit vents. Federal housing authority recommends a minimum of at least 1 square foot of attic ventilation for every 300 square feet of attic floor space evenly split between intake and exhaust. It s time to install. After that find out the vent s nfa as rated by the manufacturer.

Thus if your attic is 450 square feet you need roof vents equaling 3 square feet. Lsv8 metal continuous soffit vents lineal feet 31 eap 4x12 plastic soffit vents. And this guideline you ll need a minimum of. The federal housing administration recommends 1 square foot of attic.

Attic ventilation requirements how many attic vents your roof needs industry standard for proper attic ventilation recommends for no vapor retarder type of attic insulation no paper plastic or aluminum layer between the attic floor and insulation layer 1 sq. So we would need at least six metal vents in addition to the lower soffit ventilation to meet minimum ventilation requirements. Divide the attic s square footage by 150. The calculations before indicated that we needed 2 square feet of ridge or upper roof ventilation.

Use the calculator below to find out how many exhaust and intake vents you will need on your house. This calculator gives you the required attic ventilation requirement. Based on your 1100 sq. Feet of attic space divided 50 50 between the inlets and outlets.

Two square feet equals 288 square inches.