Intumescent Seals is a division of Dixon International Group Limited



THERM-A-STRIP is a low pressure intumescent strip material which has been developed for applications where a pressure forming product is disadvantageous. The degree of expansion is moderate in order to provide some resistance to erosion.


THERM-A-STRIP has been developed to provide excellent sealing properties combined with the benefit of a flexible strip of intumescent material. It is particularly useful in cases where there is a possibility of localized flaming due to combustible products since it generates fire retardant gases when heated.


fire door

THERM-A-STRIP can be supplied in a variety of shapes so that it can be used in a wide range of applications including gaskets for ironmongery protection i.e. locks, latches, bolts, hinges etc. It is also useful in applications where the gap to be filled is small and the fire retardant properties are beneficial such as overpanels.


THERM-A-STRIP is a flexible phosphate based intumescent product giving an approximate ten fold increase in volume when exposed to heat. Its activation temperature is around 180°C. THERM-A-STRIP is supplied in a natural white finish which, because of its resistance to both atmospheric moisture and carbon dioxide, requires no additional surface protection. The material may be decorated with a wide range of conventional finishes without impairing the performance. It is available with or without a self-adhesive backing strip.



THERM-A-STRIP is supplied as standard white but it can be coloured if required.*

Contact our Technical Department for further information.

Nominal sizes are available in the following dimensions:

  • 10 mm x 2 mm
  • 15 mm x 2 mm
  • 20 mm x 2 mm
  • 25 mm x 2 mm
  • 30 mm x 2 mm
  • 38 mm x 2 mm

And in standard lengths of 1050 mm and 2100 mm. Other sizes and lengths are available to special order.

Other thicknesses from 1 mm upwards, widths up to 130mm wide and lengths up to 3000 mm are available on request.

* Colours may vary slightly between examples illustrated in print, online and actual examples - which will depend upon lighting conditions in situ.

Test Evidence

THERM-A-STRIP has been successfully tested as a component of various doorsets to meet the fire resistance performance requirements of BS 476:Part 20 & 22. It is currently being evaluated to BS EN-1634-1.

Copies of test reports and assessment evidence are available on request.

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Related Products

When THERM-A-STRIP is used for bespoke applications it may be beneficial to use it in conjunction with other products to enhance its performance.

Please contact our Technical Department for further advice.