Attic Air Flow Calculation

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.

Attic air flow calculation.

A 50 x 30 attic would have a total area of 1 500 sq. Enter square footage calculate or enter the square footage of the attic or area to be vented. If your attic is well insulated the insulation might be plugging the spaces between rafters just above exterior walls. 7 12 to 10 12 roof pitches increase the amount of ventilation by 20 percent.

The solution is to add baffles which allow air to flow past the insulation photo 9. Our passive roof vents are ul certified and rated to withstand wind pressure in excess of 200 mph. 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. Attic mold rotting of roof sheathing and framing shortened roof life cracked paint and siding failure or an overheated home.

Let s see how a standard ridge vent product will calculate out. Our roof is 50 feet long so using a standard product we will get 900 square inches of ventilating space. 11 12 roof pitch and higher increase the amount of ventilation by 30 percent. That means air can t flow from the soffit vents to the roof vents.

Taking advantage of this natural process referred to as passive ventilation is the most common way to vent an attic. Proper air circulation through the attic space helps lower cooling bills and prolongs the life of roofing materials. Hot air exhaust vents located at the peak of the roof allow hot air to escape. Standard ridge vent produces 18 square inches of ventilating area per lineal foot.

How to determine the number of attic vents. 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. Soffit vents allow outside air to. Length x width of attic in feet 150 total sq.

For projects involving vents with motors the calculation formula is different. Of total vent space needed. Proper air ventilation in the roof prevents costly problems like. Baffles are available at home centers.

Daily activities in your home such as showering dishwater laundry or having the furnace on generate heat and moisture in the air. Ft divided by 150 equals 10 sq. Let owens corning roofing help you calculate exactly how much ventilation you will need for a healthy and balanced attic with our 4 step ventilation calculator. Home attic vent calculator for years we have been working with architects and specifiers to ensure affordable roof ventilation that upholds building code standards.