Flat Roof Ventilation Requirements

A ridge vent is a ventilation strip that is placed along the ridgeline of the home.

Flat roof ventilation requirements.

In the instances where a warm flat roof has been laid ventilation isn t usually required. To meet the requirements set out by the government for thermal insulation roof ventilation may be a requirement in order to achieve the desired certification for the property. Hot roofs have the roof deck then insulation then the roofing material. Vent a cold deck dont vent a warm deck.

Duo pitch roofs greater than 20 0 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. Why is it important to ventilate a flat roof. It depends on where the insulation is installed. It makes a difference with your venting requirements if you have a warm deck insulation between the roof deck and the membrane or a cold deck insulation below the roof deck.

As the single ply roofing association spra points out this type of flat roofing is strong durable completely sealed and usually lasts at least 25 30 years. Openings in roof framing members shall conform to the requirements of section r802 7. As opposed to old built up felt roofing with joins new single ply waterproof membranes are now most commonly used. Prior to installing the ridge vent a 1 inch wide strip of roof decking is cut out along both sides of the ridgeline to allow for air movement through the vent.

The answer depends on the type of roof you have. Cold roofs and warm roofs. The requirements for a cold flat roof is to provide the equivalent of 25 000mm m of ventilation on two opposing sides of the roof in accordance with british standards bs5250 2011 control of condensation in buildings. Any type of roof from tpo to epdm can be either hot or cold.

There are two types of flat roof. Additionally if the span is greater than 10m the overall ventilation area should be increased to at least 0 6 of the total roof area. How much ventilation does a flat roof need. Attic ventilation shall not be required when determined not necessary by the code official due to atmospheric or climatic conditions.

The glidevale technical team has co. Required ventilation openings shall open directly to the outside air.