NBS Source
List your products

Designed to create window and door openings while sealing cavities between 50–100 mm wide. Fully compatible will all types of building, whether masonry, steel or timber-framed, and with PVC-U, wood, metal and composite windows and doors.

With built-in insulation the cavity closer delivers enhanced thermal efficiency to meet current Building Regulations.

Manufactured from recycled PVC-U.


  • Insulates and seals cavities around windows and doors – improving thermal performance and eliminating draughts.
  • Quick and easy to fabricate and fit, with straight cuts and slot-together fitting – saving time and money.
  • Creates a rigid template for bricklaying, with no need for dummy formers – providing an accurate, square opening every time.
  • Tough, robust design – able to withstand the most demanding site conditions.
  • Universal design – accepts all window systems.
  • Fully approved by BBA and NHBC as a closer and acceptor and complies with Accredited Construction Details (ACDs).

General information
Specification data


Black brick tie (to tie cavity closer to brickwork).


50 mm.


75 mm.

Product Options


- Framehanger:

Framehanger bracket is available for fixing cavity closers to steel or timber frames before the brick skin is built. Designed for use with the majority of 60 or 70 mm window and door systems. Where the single frame weight exceeds 150 kg an initial pre test is recommended using a mock timber frame. Consult Cavalock for details.

Third party certifications
Similar products from Cavalok Building Products Ltd