Number Of Roof Vents Required

How to determine the number of attic vents.

Number of roof vents required.

Two square feet equals 288 square inches. 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. So we would need at least six metal vents in addition to the lower soffit ventilation to meet minimum ventilation requirements.

The federal housing administration recommends 1 square foot of attic. The next step is to select a suitable exhaust vent and intake vent that fits the roof design for best performance and best aesthetics. In our case the required 4 vents for the 1200 sq ft house multiply the 144 cubic inches by 4 576 cubic inches. Feet of attic space divided 50 50 between the inlets and outlets.

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

Foot of ventilation for every 150 sq. Based on your 1100 sq. Eac 16x8 metal soffit vents. Near ridge of the roof.

Now you know how many square inches of attic roof venting you need for the roof and soffit. Thus if your attic is 450 square feet you need roof vents equaling 3 square feet. Embershield closeable soffit vents. Calculate the square footage of your attic.

It s time to install. Multiple these two. Next divide that number by 2. After that find out the vent s nfa as rated by the manufacturer.

Divide the vent s nfa into 1 100 to yield the number of vents needed either in linear feet or units pieces. 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. Lsv8 metal continuous soffit vents lineal feet 31 eap 4x12 plastic soffit vents. Eac 16x4 metal soffit vents.

This calculator gives you the required attic ventilation requirement.