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  • For sealing joints, voids/irregular holes in walls, partitions and other structures.
  • Provides primerless sealing and bonding on a wide range of substrates including ceramic, plaster, plastics, masonry, wood, stone and metals.
  • Internal sealing around doors and windows.
  • Sealing where air quality for health is important.
  • Sanitary applications including showers.
  • Sealing of gaps around fitted furniture and worktops.
  • Sealing around flooring.
  • Fire-resistant sealing.
  • Radon-resistant sealing.
  • Decorating caulking and sealing.
  • Air and sound sealing.


KemStop FR Flexi Sealant is a four hour fire rated sealant and adhesive. It is suitable for a wide variety of building trade applications including decorating, flooring, joinery, plumbing and tiling. This product is both a sealant and adhesive and free from dangerous emissions.

KemStop FR Flexi Sealant is also a non-reactive environmentally friendly chemistry that ensures compatibility with most building materials. It will move dynamically to accommodate the natural or unexpected movements of sealed/bonded joints within a building, for long-lasting performance.

Features and benefits:

  • Primerless adhesion.
  • Excellent adhesion to most common substrates.
  • Dynamic for low and high modulus applications.
  • Fast cure - max bond strength is attained in 24 hours.
  • 3D joint movement capability minimum 25%.
  • Can be used for all applications internally.
  • Fire-rated up to 4 hours both integrity and insulation.
  • Resistant against radon (radioactive particles).
  • Recommended for use in joints up to 20 mm wide, larger joints widths can be accommodated.
  • Excellent slump resistance.
  • VOC free.
  • Resistant to mould and mildew.
  • Low dirt pick up.
  • Non-staining on susceptible surfaces.
  • Easy to apply and tool off.
  • Excess can be wiped before curing with a damp cloth.
  • Paintable, low shrinkage, does not yellow.
  • Compatible with a wide range of substrates.

General information












Pr_30_31_76_40 Intumescent firestop sealantsPrimary


P12/47 Sealant

P12/390 Sealant

Specification data - Intumescent firestop sealants



Manufacturer guidance

Ready to use thixotropic paste.

Fire performance


Fire resistance

Up to class EI 240 when tested as part of a system.

Guidance for specification option:

KemStop FR Flexi Sealant maintains the integrity of a joint in a fire situation giving a minimum of 4 hours as long as the surrounding construction remains intact. Both the sealant and the backing material must be applied to a minimum depth to achieve the stated fire resistance. The type of backing material must be as specified. Consult the manufacturer's literature for details.

Reaction to fire

Classification D-s2, d0.



Radon gas resistance - Joints

Z = 2.9, 108 s/m (1.5 mm thickness).

Sound insulation

Single sided seal ≥12 mm depth: 62 dB; Double sided seal ≥12 mm depth: >62 dB.


KemStop Fire Rated Flexi Sealant Technical Data Sheet

KemStop Fire Rated Flexi Sealant Technical Data Sheet

Similar products from Kemwell Fire International Ltd

KemStop FR Acrylic Sealant

KemStop FR Acrylic Sealant