200+ Branches nationwide

You’re never far from our expert advice and huge range of 6000+ products, plus thousands more made-to-order.

50 years in the trade

For five decades, we’ve served fabricators, installers, and specifiers across the UK.

Leading the field in sustainability

Last year we recycled 3,000,000 window frames, showing our commitment to sustainable home improvement.

Unrivalled choice of Profile Systems 

We offer our fabricators the widest range of systems in the UK and the technical support to back it up.


Cavalok Cavity Closers and Window Formers

Increase the insulation and thermal values of any property - housing, public sector, commercial, or industrial - with our outstanding window and door cavity closers. Manufactured from post-consumer recycled material and BBA certified, Cavalok cavity closers can be used with masonry, timber, and steel. They are the simplest and most effective way to seal cavities around wall openings, and provide a rigid template for bricklaying and window or door installation.

Cavalok qualities at a glance

 Provides a damp-proof course

Simplifies brickwork (no return bricks needed)

Provides thermal break

Prevents condensation damage

Reduces heat loss and CO2 emissions

Meets Accredited Construction Details regulations

Compliant with Part L of Building Regulations

Multiple outstanding cavity closers

Cavalok cavity closers enable brick courses to be completed and create an air-tight receiver for windows and doors. So whatever the size or make-up of a wall, you can now quickly and cost-effectively close the cavity at window and door openings – instantly increasing a property’s thermal efficiency and reducing its energy bills. 

  • Standard Window Closers are perfect for new build projects with cavities ranging from 50mm - 300mm.
  • Specialist Entrance Door Closers are designed for use on Jambs in door openings, the product encompasses an engineered insulation for more robustness and extra fixing strength for doors.
  • FlameBlok Fire Rated Cavity Closer is suitable for cavities up to 150mm and acts as a cavity barrier to Part B, Table A1 of Building Regulations.
  • Trade Closer is ideal for refurbishment projects, with a slotted design perfect for cavities measuring 50mm-100mm.
  • Overhead vent profile Eliminates the need for unsightly through-frame ventilation with a profile to maximise airflow.

Standard Window Closers

BBA certified and fully approved by the NHBC, the Cavalok Universal Cavity Closer is tailor made to your specification with every order. Easily fitted in cavities measuring between 50mm and 100mm, it is designed with bracing options, moulded corners, and brick wall ties. Unique frame hangers, window board receptors, and overhead ventilation complete the package. Combined, these intelligent features make it a suitable choice for all window systems.

Specialist Entrance Door Closers

Cavalok Specialist Entrance Door Closers are designed specifically for Entrances where doors need to be set back into the cavity to meet building regulations. The product encompasses a Hybrid Insulation that can be direct fixed into ensuring a strong secure fix for Doors and avoid the normal need for call backs to re fix. 100mm to 150mm available from stock.

FlameBlok Fire-Rated Cavity Closer

Tested by Chiltern International and found to provide at least 60 minutes’ fire integrity and a minimum of 45 minutes’ fire insulation with timber insulation, and 90 minutes’ integrity and insulation in masonry, FlameBlok Fire-Rated Cavity Closer creates a continuous fire-rated ring around the opening. Manufactured from 100% post-consumer recycled PVC-U for minimal environmental impact, it meets BS EN 1363 standards and is suitable for cavity sizes up to 150mm.

  • Cavity barrier to Part B, Table A1 of Building Regulations
  • Reduces fire risk during construction
  • Superior thermal performance
  • Saves on-site labour
  • In testing, timber frames fail before FlameBlok

Trade Closer

Trimmed to the cavity width and retro-fitted into new build or refurbishment cavity walls, Trade Closer provides a damp-proof course and a thermal break at door and window openings. Trade Closer can be nailed to brick or block walls before final sealant and plasterboard finishing. Position windows at least 30mm over the cavity for optimum performance.

  • Meets Accredited Construction Details
  • Closes cavity at sills and jambs
  • Made from post-consumer recycled PVC-U
  • Easy fix: clout nail to brick or blockwork
  • Thermal break to prevent condensation
  • Increases energy-efficient construction
  • Suitable for new builds and refurbs

Overhead Vent

Whether it’s deepest winter or the height of summer, buildings require a regular and fresh source of air to keep them well ventilated and comfortable.

Eliminating the need for unsightly through-frame ventilation, the new Eurocell Overhead Vent provides an attractive slimline over-frame ventilation profile that maximises airflow and minimises fabrication and because it vents over the window frame, it makes it easier to meet the requirements of Part F Building Regulations.

News from Eurocell

Tips, advice, blogs, case studies, and announcements: get all the latest developments direct from Eurocell HQ. You won’t miss a thing!

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Technical Hub

Check spec sheets, CAD drawings, data sheets, certifications, and more in our Technical Hub – so your next project goes without a hitch.

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News from Eurocell

Tips, advice, blogs, case studies, and announcements: get all the latest developments direct from Eurocell HQ. You won’t miss a thing!

View news >

Cavity Closers FAQs

Here at Eurocell Home, we believe making improvements to your home should be easy, and that you shouldn’t have to break the bank to do them. That’s why we’ve worked tirelessly for years to produce high-quality products, that offer excellent value for money.

Frequently Asked Questions
What does a cavity closer do?
A cavity closer is a critical building component that seals cavities around wall openings and provides a rigid template for bricklaying, and window or door installation. Cavity closers: ·        Provide a damp proof course (dpc) ·        Provide a thermal break ·        Prevent damage from condensation ·        Reduce heat loss and CO2 emissions ·        Provides an accurate opening for the window & door
What is a check reveal?
Check reveal is a construction method of building walls where the brickwork is returned into the opening of between 15mm-20mm on the jambs. This method is primarily used for severe weather rated areas if the designer has taken consideration of the added thermal properties that having windows and doors in check reveal provides.
What is the minimum value for a thermal pass?
The minimum thermal resistance as set out by the Accredited Construction Details (ACDs) Part L is 0.45_m²K/W
Can I direct fix into a closer?
With a standard EPS filled cavity closer you cannot use as a direct fix. With high-density CF EPS material you can use a cavity closer as a fixing point.
When do I need a hybrid closer?
A hybrid cavity closer is required when the load of the window or door will be primarily over the open cavity and where the loading capacity of a standard closer will not suffice. A structural closer will also be used if a direct fix through the window into the closer is used.
Will your closers work with timber frame?
Our cavity closer system can be used on timber frame and other frame constructions using our frame hanger system. This system is designed to support the cavity closer from the internal frame prior to the erection of the external skin.
Where should the window sit on the closer?
The Accredited Construction Details (ACDs) state that the min requirement for a window to be set back into the cavity is a minimum of 30mm from the inside face of the external skin. The further the set back of the window frame with the cavity, the better the thermal performance of the junction.
Where should I brace the closer?
The bracing system spans from jamb to jamb of the cavity closer frame and allows for rigid support for transportation and installation. Optional supports on the corners can be provided for the larger cavity widths. Cavalok corner braces can be provided.
Can I support my window / door over the closer?
Windows and doors set back a min of 30mm within the cavity can be supported by a standard cavity closer as the primary load will be supported by the external skin. If windows and doors are to be installed directly over the cavity, a structural assessment will need to take place by a member of our technical team.
Where do I brick up to?
The brick or external course should be built up to cill level for the cavity closer frame to then be inserted and to be used as a guide for building of the jambs.
Which type of cavity closer do I need?
Domestic dwellings comprising of a ground floor and first floor (masonry construction) only need a non-fire related cavity closer. Masonry construction of more than two stories or timber constructions must use a fire barrier (fire-rated closer or sock) or wooden pinch baton.  This is especially important for construction in Scotland, as the majority of building is timber frame. For multiple dwellings within one unit, the builder has to provide a fire barrier for continuation of a compartmental or party wall. This also applies to terraced housing.