Everbuild Fireseal 300 is a five-hour rated, one part, emulsion acrylic based, intumescent acoustic sealant that gives a firm yet flexible seal to joints in a variety of fire rated structures. When exposed to heat, it swells greater than 3x of its original size, creating a char that will resist the passage of fire and smoke for up to 5 hours. Fireseal 300 is highly flexible and has a joint movement capability of +/- 12.5%. It can be used in joints up to 50mm wide.
The selected fillers used in this formulation also make it suitable for use as an acoustic sealant. It has excellent acoustic properties for sound deadening (average noise reduction of 29dB).


Available in:
300ml cartridge


  • Interior precast panel joints
  • Electrical Penetrations
  • Fire Walls
  • Interior window and door frames

See all applications in our Technical Data Sheet

See all applications in our Technical Data Sheet



Can Everbuild Fireseal 300 be used in external applications?

Although it is water resistant once fully cured, it is not recommended for external use. For external control joints, use Everbuild Hybriflex FR.

Does Everbuild Fireseal 300 have acoustic properties?

Yes, it has excellent acoustic properties for sound deadening, with an average noise reduction of 29dB. Further documentation can be accessed in our downloads section.

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