Masonry cavity wall constructions can be filled with a rigid full fill polyisocyanurate (PIR) insulation product, the selected product should carry third-party certification confirming its suitability for use in cavity wall applications.

How does a rigid full fill solution differ from a partial fill solution?

Rigid insulation boards for masonry cavity walls have typically been associated with partial fill applications only.

Rigid full fill insulation solutions have gained acceptance in the marketplace thanks to their design and manufacture, which ensures the inside of the building is protected from rainwater ingress even without a residual 50mm cavity.

Rigid full fill insulation boards are manufactured from the same thermally efficient foam insulation as partial fill products, and they are provided in the same convenient board size to suit standard wall tie spacing.

The primary difference is that they typically feature a profiled board edge, compared to the square edge that is common to partial fill products. The profiled edge helps boards to lock together once installed and stop any rainwater from tracking across the board joints to the inner leaf masonry.

The ability of a rigid full fill insulation solution to resist water penetration is independently tested and incorporated into third-party certification, such as a BBA certificate. Without that assessment, a product cannot be used as masonry cavity wall insulation.

About Thermaclass Cavity Wall 21

Thermaclass Cavity Wall 21 is a rigid full fill cavity wall insulation solution from Celotex. It offers a thermal conductivity of 0.021 W/m.K, a tongue and groove board edge profile, and BBA certification for full fill cavity wall applications.

Find out more by downloading the Thermaclass Cavity Wall 21 product brochure or contact our technical support team to learn more about how this solution could benefit your project.