NHBC Regulation 2011

Insulation and control of condensation:

7.2 – D11 (a) Ventilation of main roof spaces

Pitched roofs with insulation at ceiling level should always be ventilated to the outside air to minimise the risk of ventilation.

7.2 – S14

• Cross Ventilation of the roof is provided
• Insulation does not block the ventilation path at eaves level
• Insulation is laid over the whole loft area, including the wall plate
• There are no gaps in the insulation

BS5250 Control of Condensation in buildings:

When using both LR and HR roofing underlays and on all roof pitches, “the harmful effects of condensation can be controlled by ventilation beneath the roofing underlay.”

BRE Report - Thermal Insulation - avoiding risks

2.1 (c) Provide an air path to the roof space from the eaves ventilation opening equivalent to a 50mm continuous gap.
2.3 Condensation of Thermal Bridges
2.3 (a) Carry the loft insulation over the wall plate to link with the cavity insulation.