Roof Ventilation Regulations

Part h of the building regulations regarding drainage state that water should drain to one or two edges.

Roof ventilation regulations.

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. The net free vent area nfva shall not be less than 1 150 of the area of the space being vented. Warm roofs must have a vcl bonded to the deck. 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. Condensation encourages rot and mould growth. The air gap dimensions shown on the drawings are the minimum widths required for clear continuous ventilation air paths at the eaves. Roofs must be wind resistant and strong enough to walk on.

Waterproofing should extend up the adjacent walls at least 150mm from the roof surface. 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. Roof voids must be ventilated in order to stop warm air condensing on cold surfaces. Required ventilation openings shall open directly to the outside air and shall be protected to prevent the entry of birds rodents snakes and other similar creatures.

These ventilation needs are calculated differently. R806 2 minimum vent area.