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CV Strips for New Build Homes

Envirograf Cavity Barrier Strips around window

Installation of Product 55 – Cavity Barrier CV Strips around openings to provide protection for hundreds of new-build residential homes

In November 2020, NHBC updated its standards on Cavity Barriers to include the following:

6.1.4    The cavity in the masonry cavity wall of a building can provide a route for the spread of smoke and flames. Cavities should be closed with cavity barriers, in accordance with Building Regulations.

Cavity barriers should be provided:

  • at the edges of cavities, including around openings e.g. window and doors;
  • where the cavity abuts compartment walls and floors, and;
  • where to break up extensive cavities which could act as a route for fire spread.

Cavity barriers need to achieve a minimum of 30-minute fire resistance.

On a site in Canterbury in Kent of up to 500 new dwellings, our CV Cavity Barrier Strips were used to fire protect new builds. Due to the new NHBC standards, we ensured these were being followed on site. You can see the Strip run along the top of windows and openings and run consistently along compartment walls and floors.

The CV Cavity Strip is a flexible strip barrier that in the case of a fire will expand and seal the cavity for up to 120minutes of fire protection. It’s a thin flexible strip that contains high expansion intumescent wrapped in robust blue plastic sleeving to resist damage. The CV strips come with double-sided tape to help with adhering the product before mechanically fixing back with stainless steel fixings to the substrate at 300mm centres. We offer a wide variety of CV Cavity barrier strips to suit different cavity gap sizes. Contact us today for more information.


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Envirograf ® products are tested to British Standards & European Standards at approved test centres.

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