Ensuring your home has the proper attic ventilation according to these guidelines however can save yourself the stress and hassle of an emergency roof repair.
Formula for proper attic ventilation.
You can also contact your local municipality to check on building code in your area.
According to the national roofing contractors association nrca a power vent with an airflow rate of 1 0 cubic foot per minute per square foot of attic space measured at the attic floor is generally considered to be equivalent to a 1 150 ventilation ratio.
1 500 square feet 300 5 square feet.
1 100 square inches of intake net free area needed.
Next multiply the 4 square feet into cubic inches.
Remember the minimum area requirement when using a continuous system is a ratio of 1 300.
Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca.
There is a generally agreed upon formula that you can apply for balanced attic ventilation known as the 1 150 rule.
In order to find the right calculator divide the attic floor space by 300 sq feet.
1 100 square inches of exhaust net free area needed.
Calculate or enter the square footage of the attic or area to be vented.
See how simple that was.
2 200 2.
It states that for every 150 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.
Length x width of attic in feet 150 total sq.
Cool air in hot air out.
In our case the required 4 vents for the 1200 sq ft house multiply the 144 cubic inches by 4 576 cubic inches.
The next step is to select a suitable exhaust vent and intake vent that fits the roof design for best performance and best aesthetics.
Of attic space you need 1 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.
Tips for assessing your needs.
Now let s figure out how much ventilation space we need.
Ok so now we know the square footage of the attic area to be ventilated.
1 cubic foot is 12 x 12 144 cubic inches.
Calculate the total vent area needed 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.
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.
