Roof Ventilation Regulations

The net free vent area nfva shall not be less than 1 150 of the area of the space being vented.

Roof ventilation regulations.

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. 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. These ventilation needs are calculated differently. The air gap dimensions shown on the drawings are the minimum widths required for clear continuous ventilation air paths at the eaves.

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. Condensation encourages rot and mould growth. Waterproofing should extend up the adjacent walls at least 150mm from the roof surface. R806 2 minimum vent area.

Warm roofs must have a vcl bonded to the deck. Roof voids must be ventilated in order to stop warm air condensing on cold surfaces. Part h of the building regulations regarding drainage state that water should drain to one or two edges. Roofs must be wind resistant and strong enough to walk on.

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 key to proper ventilation of your roof and attic is balance.