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.
Required residential roof vents.
Typically building codes include minimum requirements applicable to attic ventilation.
Ventsure 4 foot strip heat moisture ridge vent.
Vent pipes shall terminate not less than 6 inches above the roof measured from the highest point where the vent intersects the roof.
The roofing industry also has practical guide lines for attic ventilation.
Code requirements the international building code.
Before we explore how to ventilate an attic space it is prudent to understand how much ventilation is needed.
Ventilation can be accomplished using various products and techniques.
Effective attic ventilation systems reduce damaging heat and moisture in your attic promote energy efficiency by helping to reduce the load on your air conditioner in the summer and also reduce the risk of ice dam formation on your roof.
Choose one of the following products to meet the recommended exhaust nfva of 528 square inches.
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.
They are easy to install under the roof s overhang which is known as the soffit are generally hidden from sight and provide excellent protection from weather outdoor debris and pests while still allowing air to flow into the attic.
Continuous or individual soffits.
Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca.
The following are the requirements taken directly from the irc.
If your roof is 1200 sq ft soffit floor space you will need 4 sq feet of roof ventilation.
Proper attic ventilation can be an impor tant performance consideration when design ing and installing steep slope roof systems.
In our case the required 4 vents for the 1200 sq ft.
1 cubic foot is 12 x 12 144 cubic inches.
The ventilation amount and opening size requirements can be found in section 806 roof ventilation of chapter 8 roof ceiling construction.
Next multiply the 4 square feet into cubic inches.
The majority of the requirements related to attic ventilation have not changed much from the previous editions.
In order to find the right calculator divide the attic floor space by 300 sq feet.
Where a roof is used for any purpose other than weather protection vents shall extend at least 7 feet above the roof and shall be properly supported.
Taking advantage of this natural process referred to as passive ventilation is the most common way to vent an attic.
Soffit vents are one of the most popular intake vent styles.
