Cavity Formers

Cavity formers ensure window openings are ready for installation.

Cavity Formers

Cavity Formers are the simplest, most effective way to seal cavities around wall openings and provide a rigid window or door frame template. As well as acting as a brickwork former, they enhance thermal efficiency, create a damp-proof course and prevent thermal bridging in accordance with Part L of the Building Regulations.

  • 2, 3 or 4 sided cavity formers.
  • Closes any size cavity between 50mm and 300mm.
  • Circles, arches, ovals and combination T or P shape frames.
  • BBA certified and meet Part L of the Building Regulations.

Benefits of Cavity Formers.

Built-in thermal efficiency

Cavity formers incorporate an insulated core, which not only improves thermal efficiency for Part L Building Regulations compliance, but also saves time on site because no additional insulation needs to be fitted.


Cavity formers are very easy to install and eliminate the time-consuming process of fitting.

Prevent cold-bridging, condensation and mould

Using rigid cavity formers achieves a close fit around all building apertures to prevent draughts. It creates an effective damp-proof barrier and prevents cold-bridging, condensation and mould growth.

Eco-friendly made from 100% recycled material

Cavity formers are manufactured entirely from recycled post-consumer waste. Today, with the Code for Sustainable Homes offering credits to builders who use sustainable materials and energy-efficient products, Cavalok cavity closures are the obvious choice for every new-build project.