How Much Roof Ventilation Do I Need

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.

How much roof ventilation do i need.

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. Jones takes this measurement and divides it by 150 for a total of 7 36 square feet of ventilation space that is needed. Jones must now take this required ventilation space and compare it against the total ventilation that he currently has for his attic space. 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.

Generally speaking you need a ratio of 1 300 where for every 300 square feet of ceiling space you need 1 square foot of attic ventilation. That said air resistance and interference such as vent grates reduces the area of true ventilation. Also your building codes may dictate how many and which kind of vents you need to use. Use these numbers to select proportion and place static ventilation products.

Based on your 1100 sq. This shortcut conveniently calculates the 2015 international residential building code minimum irc section r806 roof ventilation 1 which states in part 1 square foot of net free area for every 150 square feet of attic floor space with the attic defined as length x width floor of the attic. That depends on a few different variables including the size of the roof the roofing material and what the building will be used for. And this guideline you ll need a minimum of.

Thus if your attic is 450 square feet you need roof vents equaling 3 square feet. Near ridge of the roof. 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. To calculate the ventilation required with such a vapor barrier divide the square footage of the attic by 300 instead of 150.

As a general rule your roof needs 1 square foot of vent area for every 150 square feet of attic space. In order to facilitate this exchange of warm and cool air the general rule of thumb suggests installing at least 1 sq. Of vent for every 300 sq. Static ventilation needs may be reduced if you have an uninterrupted ceiling vapor barrier installed with a rating of 0 1 perm or less.

Building codes vary.