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Cavity Closers

cavity closers by Nationwide windows and doors
cavity closers by Nationwide windows and doors
cavity closers by Nationwide windows and doors

We supply the most widely used frame forming closure in the UK. The Cavalok cavity closer takes all the hassle, time and uncertainty out of creating windows and door openings in new buildings.

Any new build project will benefit from these quick to create, precise, rigid, robust openings that are fully compliant with Building Regulations and Accredited Construction Details and are NHBC and BBA approved.

Cavity Closers

Features & Benefits

Simplifies Brickwork

Eliminates the need for return bricks, resulting in a simpler and more efficient construction process

Thermally Broken

Provides a thermal break to effectively curb heat loss, leading to decreased CO2 emissions


Compliant with Part L of Building Regulations, for full compliance

Faster Delivery Times

Increases on-site efficiency to help deliver projects on time

Increased Accuracy

Negates the need for survey, saving time and ensuring accuracy

No Damp or Condensation

Provides a damp-proof course and prevents condensation damage

How Cavity Closers Work

Providing a rigid bricklaying template, window acceptor, damp-proof course and thermal break all-in-one, the PVCu Cavalok cavity closure range is designed to create window and door openings while sealing cavities between 50mm and 300mm wide.

In addition, its built-in insulation delivers enhanced thermal efficiency and it is also manufactured entirely from post-consumer recycled PVCu. Fire-rated cavity closers can also act as a barrier to enhance fire protection in your buildings.

We offer a range of cavity closer products to fit cavities from 50mm to 300mm wide, catering for every type of building:

Cavalok Cavity Closer

Insulated closer for 50mm-100mm cavity walls


Combined fire barrier and insulated cavity closer


Insulated cavity closer for buildings with wider cavities, from 125mm to 300mm wide

Why choose Nationwide?

Our History

Over 30 years of experience in our chosen markets - new build and social housing

Scale You Can Rely On

We manufacture and install one product, every minute of every working day

Investment In People

We are the only fabricator to have an in-house GQA approved centre for training and qualifications

Quality Assurance

Stringent quality control maintains our reputation for delivering high quality products and installations