Attic Air Flow Calculation

Hot air exhaust vents located at the peak of the roof allow hot air to escape.

Attic air flow calculation.

Length x width of attic in feet 150 total sq. 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. 11 12 roof pitch and higher increase the amount of ventilation by 30 percent. Soffit vents allow outside air to.

How to determine the number of attic vents. Daily activities in your home such as showering dishwater laundry or having the furnace on generate heat and moisture in the air. Baffles are available at home centers. Up to 6 12 roof pitch use the standard formula as explained in this article.

Nine hundred square inches equals 6 25 square feet. Of total vent space needed. 7 12 to 10 12 roof pitches increase the amount of ventilation by 20 percent. Proper air circulation through the attic space helps lower cooling bills and prolongs the life of roofing materials.

That means air can t flow from the soffit vents to the roof vents. Our roof is 50 feet long so using a standard product we will get 900 square inches of ventilating space. Standard ridge vent produces 18 square inches of ventilating area per lineal foot. Home attic vent calculator for years we have been working with architects and specifiers to ensure affordable roof ventilation that upholds building code standards.

For projects involving vents with motors the calculation formula is different. Ft divided by 150 equals 10 sq. Calculate the total vent area needed. Let s see how a standard ridge vent product will calculate out.

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. Proper air ventilation in the roof prevents costly problems like. 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. If your attic is well insulated the insulation might be plugging the spaces between rafters just above exterior walls.

Taking advantage of this natural process referred to as passive ventilation is the most common way to vent an attic. The solution is to add baffles which allow air to flow past the insulation photo 9. Attic mold rotting of roof sheathing and framing shortened roof life cracked paint and siding failure or an overheated home. A 50 x 30 attic would have a total area of 1 500 sq.