Envirograf Intumescent Letterbox Liner

Availability: In Stock


An intumescent letter box liner comprising two adhesive L-shaped sections which are fitted into existing mail apertures.

Used for improving the fire rating of existing letter box apertures.


An intumescent letter box liner in two L-shaped sections with double-sided tape on the back for easy fixing, which can be cut to suit the size of the opening. Non-standard sizes can be made to order. For existing letter box openings in fire doors or where existing and internal letter box flaps wish to be used. Aperture sizes up to the limit for each type (LBL1 & LBL2) can be accommodated by cutting the liner with a sharp knife as required. A bare wood opening must be sealed with a paint or wood sealer before fixing. To fit doors from 38mm to 70mm thick.


  • Provides up to 68 minutes protection
  • Can be custom made to suit a range of aperture sizes.
  • Suitable for fitting to doors from 38mm to 70mm thick.
  • Liner can be easily cut to size to fit the opening.

Application Instructions:

2 L-shaped sections supplied with double sided tape on the back. Place long section on top of the side section and cut both angles to length. Peel off double sided tape and adhere to the inside of the opening. It is advisable to put panel pins into both side pieces.

Order References:

LBL1 (85 x 340mm).

LBL2 (65 x 290mm).


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