Intumescent Seals is a division of Dixon International Group Limited


Entrance doors to flats and apartments in multi-storey buildings are commonly required to be fire resisting to 30 or sometimes 60 minutes. As these doors generally provide the primary or often only access, many have apertures cut in them to serve as letter boxes. Such apertures clearly compromise the fire integrity of the door. THERM-A-PLATE provides a simple solution to this problem by providing a lining kit for both FD30 and FD60 specification doors.


THERM-A-PLATE is installed by lining the letter box aperture with pre cut sections of the appropriate width, typically 45mm for FD30 fire doors and 54mm for FD60 fire doors. For small letter plate apertures up to 50mm high, 4mm thick intumescent sections are used. For deeper sections up to 120mm high 6mm thick intumescent sections are used. For the largest 120mm x 300mm apertures the intumescent sections are additionally fixed with 4no. 30mm x 1.5mm steel pins at 50mm from the aperture ends and 10mm from the door faces.

The intumescent sections may be trimmed to suit the exact aperture size. It is recommended that metal letter plates ( not supplied)  are included in accordance with the appropriate code of practice BS8214:2008.    



THERM-A-PLATE intumescent kits provide a critical contribution to the fire resistance performance of fire door sets of 30 and 60 minutes construction.


THERM-A-PLATE kits are available in the following standard sizes:

Aperture FD30 FD60
50mm x 250mm LPTA45 LPTA54
85mm x 250mm LPTC45 LPTB54
120mm x 300mm LPTC45 LPTC54


Test Evidence

THERM-A-PLATE kits performance has been proven in full scale fire resistance tests BS476-20:1987 on fire doors of 30 & 60 minutes construction.