Renovation Above Rafter Insulation


Renovation Above-Rafter Insulation for Roofs

DuPont™ Tyvek® and AirGuard® can help you get the most out of renovation above-rafter insulation by protecting it from moisture and uncontrolled air leakage.

Renovation above-rafter insulation is often the preferred option when renovating roofs from the outside or repairing structural damage – especially when construction conditions do not permit renovation from within. To avoid heat loss and moisture damage, it pays to install an airtight roof membrane such as DuPont™ Tyvek® or DuPont™ AirGuard® between the rafters and the above-rafter insulation. This will improve the insulation properties of the building envelope and provide proven, durable protection. Depending on the building structure and the insulation material, either a vapour-open (DuPont™ Tyvek®) or vapour-closed (DuPont™ AirGuard®) membrane should be used.

DuPont™ Tyvek® and DuPont™ AirGuard® membranes are specially designed to minimise condensation and convective heat loss. They reduce heat loss in winter and increase thermal comfort in summer – all without intruding on living space. They can also help to provide additional R-value that can be added to the building structure.

DuPont™ Tyvek® and DuPont™ AirGuard® are fit for use as an windtightness layer in above-rafter insulation systems. They can be installed from the exterior without any problems.

Our recently developed AirGuard® Smart membranes go even further. These moisture adaptive (‘variable Sd’) membranes adjust their water vapour permeability automatically as humidity levels change.

The vapour resistance of DuPont™ AirGuard® Smart lies between 0.26MNs/g and more than 150 MNs/g, (Sd value 0.05m – more than 30m). In dry building structures, DuPont™ AirGuard® Smart acts as a traditional air and vapour control layer (AVCL), providing effective condensation control and airtightness. Even in temporarily high air humidity zones, water vapour diffusion is reduced and excess moisture in the envelope can dry out, both to the inside and outside.


Building In Energy


Tyvek® Supro at the Jamaica Inn: Reliable resistance for a windswept cultural icon

The famous Jamaica Inn is situated 280metres above sea level on Bodmin moor. The roof of its new accommodation extension benefits from advanced breather membrane Tyvek® Supro, which is fully compliant with BS5534:2014