How Much Air Flow Does My Attic Need

The soffit vents allow convective air movement from the soffits of the residence to the ridge vent.

How much air flow does my attic need.

First determine your attic area by multiplying the length by the width. Then aim for about 1 sq. Attic for example has an area of 1 200 sq. A 50 x 30 attic would have a total area of 1 500 sq.

That said air resistance and interference such as vent grates reduces the area of true ventilation. A 30 x 40 ft. Ft divided by 150 equals 10 sq. Multiply the length of the attic times the width in feet to find the attic area then divide by 150 to find the total square feet of vent space needed.

An attic baffle is simply an item to regulate the flow of air aka required roof venting and impede it the insulation from interfering with each other. This characteristic of air may be used to help create a flow of air ventilating the attic. In order to facilitate this exchange of warm and cool air the general rule of thumb suggests installing at least 1 sq. By my calc pxr squared says area of exhaust vent is 165 square inches.

Of total vent space needed. Exhaust fan is 14 5 inches in diameter so i figure given this is going to be a tight box i gotta put some intake vent on it and want air intake starting at the bottom and distributed around so all sides of generator get cooling and air flow. Calculate the total vent area needed. Federal housing authority recommends a minimum of at least 1 square foot of attic ventilation evenly split between intake and exhaust for every 300 square feet of attic floor space.

In addition insulation baffles must be installed at the point where the attic floor meets the roofline to prevent the attic insulation from migrating into the cavities and restricting the airflow from the soffit vents. Placing exhaust vents in the roof the gables or at the ridge of the roof and providing adequate air intake vents in the soffits best accomplishes this. This results in a constant upward air movement due to the buoyancy of warmer air. How many vents do you need.

Length x width of attic in feet 150 total sq. I need additional exhaust ventilation in my roof with the planned installation of a whole house fan in the attic of my home located in sf bay area. You mention exhaust vents shouldn t exceed intake vents in the roof for proper circulation. However with only two 1 ft x 2 ft gable roof vents i ll need an additional 7 sq ft of exhaust vents.

So now comes issue of air intake. Of vent for every 300 sq. Proper attic ventilation consists of a balance between air intake at your eaves soffits or fascias and air exhaust at or near your roof ridge.