FBLS Fire Block Grille

Three types of fire block grilles or louvres - two simple black ones and a steel mesh version.

Fire block grilles are fitted to fire-rated doors that require ventilation. Standard louvres allow air flow to a room, but will also permit flames and smoke to pass through the door. Zero’s Fire Block Louvre System (FBLS) will maintain the integrity of fire doors, allowing ventilation but preventing the spread of fire. The complete set consists of:

  • An intumescent fire block grille just 14mm thick fitted in the door leaf.
  • A two-part steel louvre set fixed to both sides of the door to hold the fire block in place.

In the event of a fire, the intumescent material expands to 80 times its original volume. It fills the ventilation void and preventing the spread of flames and smoke.

The FBLS fire block grille is suitable for:

  • Timber fire doors that have been tested for integrity of up to 60 minutes.
  • Steel fire doors that have been tested for integrity of up to 240 minutes.

We stock 14 standard sizes, including 610mm x 610mm and 457mm x 1524mm (width x height). Order any size from a minimum 152mm x 152mm cut-out.

Fire block grille louvre frames are supplied in galvanised mild steel, grey-primed and ready for powder coating. Powder-coated finishes and stainless steel frames are available for special order. Our FBLS louvres suit doors with a minimum thickness of 44mm upwards (no maximum). We can also provide fire-rated fusible link louvres and standard non-fire rated louvres.


You can fit fire block grilles to any area that needs ventilation but that is protected by a fire-rated door. Here are a few examples:

  • Plant room doors
  • Stores
  • Computer rooms
  • Server rooms
  • Changing facilities
  • Manufacturing areas


Take a look at the full product details and catalogue, or phone +44 (0) 1785 282910 for assistance.