Recommended Ventilation Requirements

The typical scenarios cover cold roofs (when the insulation is at ceiling joist level) and warm roofs (when the insulation follows the line of the rafter). When we discuss roof space ventilation we often refer to low level (eaves) ventilation and high level (ridge) ventilation.

Generally high level ventilation can be provided by the use of our Roll Fix Dry Ridge systems or vent tiles. Similarly, low level ventilation can be provided by the use of our range of eaves ventilation products or vent tiles.

The equivalent of a continuous 10mm ventilation opening at low level, combined with the equivalent of a continuous 5mm ventilation opening at high level for roof pitches over 35° and spans greater than 10m. 

For roof pitches below 15° the low level ventilation should be increased to the equivalent of a 25mm ventilation opening.

The equivalent of a continuous 10mm ventilation opening at low level combined with the equivalent of a continuous 5mm ventilation opening at high level. 

For roof pitches below 15° the low level ventilation should be increased to the equivalent of a 25mm ventilation opening.

The equivalent of a continuous 25mm ventilation opening on opposite sides.

The equivalent of a continuous 10mm ventilation opening at low level, with the equivalent of a continuous 5mm ventilation opening immediately below and 10mm immediately above each dividing wall, ensuring each void is ventilated.

The equivalent of a continuous 25mm ventilation opening at low level combined with the equivalent of a continuous 5mm ventilation opening at high level. A 50mm air gap between the insulation and underlay should be maintained.