Insulating Above And Between The Rafters

“…is well suited to new build projects and to refurbishments…”

Ballytherm insulation may be used to form warm pitched roofs by applying it over and between the rafters.
Applying a layer of insulation over the rafters brings the whole roof within the insulated envelope and maximises the available head room. This method is well suited to new build projects and to refurbishments where the roof covering is being stripped off and replaced.

The properties of Ballytherm insulation match those required for this application: its low thermal conductivity minimizes the thickness of insulation required, whilst it is strong enough to support the loads imposed from the roof covering via the battens.

The Ballytherm boards should be set in two layers, one extending in a continuous layer over the top of the rafters, which is restrained by counter battens, and the second cut to fit between the rafters and held in place by battens, clips or partially driven nails. The insulation is protected by the internal finish fixed to the underside of the rafters. The reflective surface of the boards reduces radiation heat loss across the air spaces and further improve the thermal performance of the roof.

The thickness of Ballytherm insulation required to meet regulations may be determined from table 10.

Table 10

Further Advice & Information

For more information about Ballytherm products, technical advice, or guidance on the suitability of our products for your project, contact us at + 353 (0)49 95 27000,, email us at or use our contact form.

Roof Insulation

Design Guidance