Warm roofs generally do not require ventilation as there should be an Air & Vapour Control Layer (AVCL) or vapour barrier on the warm side of the insulation to prevent the passage of warm moisture laden air to the colder uninsulated parts of the roof.

Where the insulation follows the line of the rafters, often referred to as a ‘hybrid’ roof, this may or may not require ventilation depending upon the design detail and the roof covering type.