FEB GRC fibreglass concrete windowsill
The FEB GRC reinforced fibreglass concrete window cill simply retrofits on top of the existing sill to provide the necessary clearance for external insulation.

Once bonded in place it is virtually indistinguishable from a conventional concrete window cill.

Unlike competitors’ aluminium cills, the GRC cill does not rattle or clang when struck by heavy rain or hail and can be finished with any masonry finish, paint or render. The fibreglass reinforcement makes the cill extremely robust, and once bonded in place it is virtually indistinguishable from a conventional concrete window cill. The FEB GRC window cill requires minimal maintenance and can easily be finished with a maintenance-free render if desired.

FEB GRC Window Cill Application

The FEB GRC window cill is designed to accommodate the refurbishment and retrofitting of external insulation. The lightweight concrete is both aesthetically pleasing and durable and can be used in all applications where retrofitting is required.


The FEB GRC window cill is a ready to use and is resistant to adverse weather conditions. The lightweight cill is a cement based composite material with alkali-resistant fibres that are randomly dispersed throughout the product. The glass fibres add flexural, tensile and impact strength. The resulting material allows the production of a strong yet lightweight durable product.

Advantages of the FEB GRC window cill

  • High strength to weight ratio
  • Reduced weight leads to lower transport and erection costs
  • Maintenance free, no steel to corrode
  • High impact strength
  • Improved surface detail
  • Non-combustible
  • Premium quality finish

Find out more about the FEB GRC window Cill

Fast EcoBuild are sole agents for the FEB GRC window cill. If you wish to place an order or if you want to know more about our products, contact Fast EcoBuild.