Roof Space Ventilation Requirements

Proper attic area ventilation is an important performance consideration for a home or building with a steep slope roof.

Roof space ventilation requirements. Typically building codes include minimum attic space ventilation requirements as well as the roofing industry weighing in on practical guidelines. Condensation encourages rot and mould growth. Ventsure 4 foot strip heat moisture ridge vent 27 lineal feet required. 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.

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 should also be a 50 50 balance of attic venting and roof venting. Bs 5250 sets out the minimum requirements for roof space ventilation. If your roof is 1200 sq ft soffit floor space you will need 4 sq feet of roof ventilation.

Most building codes require a ratio of 1 150 ventilation space to attic floor space. With the many well documented benefits of dry fix systems it also makes perfect. Ventilation at the eaves. For example in the average house with a cold loft there should be a minimum of a 7mm continuous ventilation gap at eaves when using a vapour permeable underlay with a normal unsealed ceiling.

Roof voids must be ventilated in order to stop warm air condensing on cold surfaces. In order to facilitate this exchange of warm and cool air the general rule of thumb suggests installing at least 1 sq. Building codes vary. 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.

According to their requirements you should have 1 square foot of attic ventilation per 300 sq ft of attic floor space. 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. The air gap dimensions shown on the drawings are the minimum widths required for clear continuous ventilation air paths at the eaves.

Roof vents choose one of the following products to meet the recommended exhaust nfva of 528 square inches.