Number Of Roof Vents Required

Embershield closeable soffit vents.

Number of roof vents required.

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. And this guideline you ll need a minimum of. 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.

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. Eac 16x4 metal soffit vents. Two square feet equals 288 square inches.

The federal housing administration recommends 1 square foot of attic. Lsv8 metal continuous soffit vents lineal feet 31 eap 4x12 plastic soffit vents. Based on your 1100 sq. As a general rule your roof needs 1 square foot of vent area for every 150 square feet of attic space.

The calculations before indicated that we needed 2 square feet of ridge or upper roof ventilation. So we would need at least six metal vents in addition to the lower soffit ventilation to meet minimum ventilation requirements. Next divide that number by 2. Feet of attic space divided 50 50 between the inlets and outlets.

Multiple these two. Measure the length and width of the attic space using a tape measure. A normal metal pot vent produces only 50 squares inches of free net area. It s time to install.

Near ridge of the roof. After that find out the vent s nfa as rated by the manufacturer. Divide the attic s square footage by 150. Thus if your attic is 450 square feet you need roof vents equaling 3 square feet.

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. The next step is to select a suitable exhaust vent and intake vent that fits the roof design for best performance and best aesthetics. Foot of ventilation for every 150 sq. Now you know how many square inches of attic roof venting you need for the roof and soffit.

How to determine the number of attic vents.