When exhausted directly outside.
Roof venting requirements.
Ft of net free venting.
Section r806 roof ventilation r806 1 ventilation required enclosed attics and enclosed rafter spaces formed where ceilings are applied directly to the underside of roof rafters shall have cross ventilation for each separate space by ventilating openings protected against the entrance of rain or snow.
Measure the length and width of the attic floor space to be ventilated.
Before we explore how to ventilate an attic space it is prudent to understand how much ventilation is needed.
Ft or more of unobstructed roof venting also known at 2 7 sq.
Ventsure 4 foot strip heat moisture ridge vent 27 lineal feet required.
Theinternational building code 2012 edition ibc 2012 requires enclosed attics and enclosed rafter spaces formed where ceilings are applied directly to the underside of roof framing to have cross ventilation for each separate space.
Building codes vary.
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.
Enclosed attics and enclosed rafter spaces formed where ceilings are applied directly to the underside of roof rafters shall have cross ventilation for each separate space by ventilating openings protected against the entrance of rain or snow.
According to their requirements you should have 1 square foot of attic ventilation per 300 sq ft of attic floor space.
N a the exception to this rule is when using a whole house fan that ducts directly to the outside of your home.
Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca.
Ventilation can be accomplished using various products and techniques.
Most building codes require a ratio of 1 150 ventilation space to attic floor space.
The net free vent area nfva shall not be less than 1 150 of the area of the space being vented.
The key to proper ventilation of your roof and attic is balance.
If your roof is 1200 sq ft soffit floor space you will need 4 sq feet of roof ventilation.
Roof vents choose one of the following products to meet the recommended exhaust nfva of 528 square inches.
