How Many Attic Rafter Vents Do I Need

Of vent space for every 150 sq.

How many attic rafter vents do i need.

With the attic vent chute installed close to the bathroom vent discharge register the warm and humid air will always find its way back into the attic and often result in condensation mold growth. Calculate how many rafter vents you need. How many attic vent chutes rafter baffles do you need to optimize attic ventilation. How many attic soffit vent truss chutes do i need.

Multiply those two numbers and then divide by 150 to get the vent space square footage. And this guideline you ll need a minimum of. From left to right air flows through the soffit vents up over the baffles allowing for the required roof venting. The general rule is that you must have one square foot of vent space for every 150 square feet of attic area.

Near ridge of the roof. Measure the length and width of the house in feet. Your living area is wrapped with insulation which you heat and cool not the attic. You want to keep the warm moist air from the house from causing moisture on the underside of the roof.

To install the rafter vents staple them directly to the roof decking. Per the 2009 irc r806 3 vent and insulation clearance insulation shall not block the free flow of air. The rule of thumb on the amount of vent space needed is approximately 1 sq. 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 code associated issues. Thus if your attic is 450 square feet you need roof vents equaling 3 square feet. So if your attic is 1 500 sq. Rafter vents come in 4 foot lengths and 14 1 2 and 22 1 2 inch widths for different rafter spacings.

Rafter vents ensure the soffit vents are clear and there is a channel for outside air to move into the attic at the soffits and out through the gable or ridge vent. As a general rule your roof needs 1 square foot of vent area for every 150 square feet of attic space. Based on your 1100 sq. You may not need ventalation in each roof rafter bay but i doubt it will harm anything.

Of vent for every 300 sq.