Partial Fill Cavity Wall Insulation

Insulating partial fill cavity walls

Thermal Performance

The thermal performance of cavity walls may be improved by installing Ballytherm insulation within the cavity. This method is well suited to new build projects. The properties of Ballytherm insulation match those required for this application: its low thermal conductivity minimises the thickness of insulation required to meet performance standards and so limits the overall cavity width.

Ballytherm is moisture resistant and will not be affected by moisture within the cavity. Ballytherm boards should be fitted to the outer face of the inner leaf.

They should be supported on wall ties and restrained against the masonry by clips fitted over the wall ties.

The boards are available with butt edged or tongue and grooved edges. They should be installed with staggered vertical joints to give a continuous layer of insulation.

The thickness of Ballytherm insulation required to meet regulations may be determined from table 8.

Table 8

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.

Floor Insulation

Design Guidance