Insulating Roofs with Pavatex Wood Fibre

Insulating Roofs

Pavatex Roof Insulation Solutions


Insulating Roofs with Pavatex Wood Fibre

External Roof Insulation

A roof can be insulated at rafter level if the roof space is to be lived in such as with converted lofts, vaulted ceilings and dormer bungalows. The most effective method is to insulate the roof externally. This involves laying Isolair Multi wood fibre sarking boards above the rafters and placing Pavaflex or Pavatextil P flexible insulation between the rafters. This setup eliminates thermal bridging through the rafters, significantly improving the U-value of the roof. Known as a warm roof, this approach is recommended for new roofs or during roof renovations when tiles are being replaced. With external roof insulation, the rafters can be fully filled with insulation, as the ventilation space will be above the wood fibre sarking board, between vertical counter-battens.

Pavatex wood fibre insulation adds substantial thermal mass to the roof, helping regulate internal temperatures during summer by storing excess heat for up to 10-12 hours. Additionally, the high density of wood fibre significantly enhances acoustic insulation. Wood fibre also buffers moisture, maintaining optimal relative humidity levels, resulting in a healthier and more comfortable home or workplace environment.

Internal Roof Insulation

For existing roofs where tiles don’t need to be removed, insulation can be installed from the inside. However, it’s crucial to maintain a minimum 45mm ventilated cavity space to allow water vapour to evaporate through the eaves, and if possible, the ridge too. We recommend fitting the water-resistant Isolair Multi board between the rafters or draping the Pavatex ADB Breather Membrane up and between the rafters to protect the flexible wood fibre insulation from external moisture. If room height allows, Isolair Multi wood fibre board can be fitted to the underside of the rafters to reduce cold bridging.

This internal roof insulation system will also reduce summertime overheating and will add considerable acoustic insulation to the roof. It will greatly enhance the internal microclimate as wood fibre is a healthy, natural material without any added toxins and it absorbs and releases excessive humidity so that it can evaporate away.  This will greatly reduce the risk of condensation and mould growth on ceilings.