Roof Space Ventilation Requirements

Ventsure 4 foot strip heat moisture ridge vent 27 lineal feet required.

Roof space ventilation requirements.

Building codes vary. According to the fha federal housing administration us for every 300 square feet of attic floor area you should have at minimum one square foot ventilation. Measure the length and width of the attic floor space to be ventilated. Most building codes require a ratio of 1 150 ventilation space to attic floor space.

If your roof is 1200 sq ft soffit floor space you will need 4 sq feet of roof ventilation. 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. The air gap dimensions shown on the drawings are the minimum widths required for clear continuous ventilation air paths at the eaves. There should also be a 50 50 balance of attic venting and roof venting.

This pk topic provides commonly accepted ventilation practices compatible with a decra roof system installation. In order to facilitate this exchange of warm and cool air the general rule of thumb suggests installing at least 1 sq. Condensation encourages rot and mould growth. Roof voids must be ventilated in order to stop warm air condensing on cold surfaces.

Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca. Hence you would need two square feet 600 300 of attic ventilation. As an example in an attic that is 30 feet by 20 feet you would have 600 square feet of floor area. The key to proper ventilation of your roof and attic is balance.

Ventilation at the eaves. You can also contact your local municipality to check on building code in your area. According to their requirements you should have 1 square foot of attic ventilation per 300 sq ft of attic floor space. Duo pitch roofs greater than 200 pitch or greater than 10m span should have additional ventilation at the ridge to assist airflow through the roof void equivalent to at least a 3 mm wide continuous gap.

The amount of space you devote to intake must be equal to the amount you allow for exhaust and these must be calculated according to the size of your attic and slope of your roof. Typically building codes include minimum attic space ventilation requirements as well as the roofing industry weighing in on practical guidelines.