Home > Companies > Eurocell plc > BigBlok Cavity Closer

With larger cavities being specified across new-build properties in order to meet stringent thermal efficiency regulations, BigBlok is meeting the demand for a simple slot-together system that quickly and cost-effectively closes off window and door openings of any size in any type of wall. Making it an essential component for low U-value construction, helping to achieve higher ratings in the Code for Sustainable Homes.

Features and benefits:

  • Creates rigid bricklaying template and seals walls with cavities up to 300 mm, helping in meeting stringent thermal efficiency regulations.
  • Manufactured from 100% post-consumer recycled UPVC – delivering a sustainable solution.
  • Closes opening with continuous CFC/HCFC-free insulation – reducing U-values to prevent thermal bridging.
  • Quick and easy to fabricate and fit, with straight cuts and slot-together fitting
  • Compatible with UPVC, timber, steel and composite doors and windows
  • Tough and robust to withstand demanding site conditions
  • Extensive range of fitting options to suit every building project


  • Meets Accredited Construction Details.
  • Meets Part L of Building Regulations.

NBS Specification

NBS Create logo
This product is associated with the following NBS Create clause:
45-25-20/455 Plastics cavity closers

NBS Specification

NBS Buliding logo
This product is associated with the following NBS clauses:

Product specification

An important note about specifying



Eurocell plc


+44 (0)1773 842100

Product reference

BigBlok Cavity closer

Cavity width

[125 mm]
[140 mm]
[150 mm]
[170 mm]
[200 mm]
[250 mm]
[300 mm]


[Not required]
[Quick fit window retainer]
[Thermal barrier]
[Cavalok corners]

Manufacturer details

Fairbrook House,
Clover Nook Road,
Derbyshire, DE55 4RF
Tel +44 (0)1773 842100
Fax +44 (0)1773 842109
NBS Plus