Trusted Fire Protection for
Internal Timber Applications
SENTRIN FRI
Sentrin FRI is a humidity-resistant, pressure-impregnated fire retardant treatment for timber used in dry or protected interior environments. Designed to meet Euroclass B or C standards, it helps slow the spread of flames, reduce smoke, and limit heat output in the event of a fire - while preserving the structural and aesthetic integrity of your timber.
Tested and certified under ISO 9001 conditions, Sentrin FRI ensures long-lasting, maintenance-free performance, and is fully compliant with UK Building Regulations.
WHY IT MATTERS
In the event of a fire, untreated wood can accelerate flame spread and smoke generation - compromising escape times and increasing building damage. Sentrin FRI chemically reacts with the combustible gases released during fire, forming a protective char that insulates the timber and slows combustion.
This treatment helps ensure that timber used in walls, ceilings, joinery, or structural interiors meets today’s strict fire safety standards - without affecting strength, appearance, or lifespan.
FIRE CLASSIFICATION & COMPLIANCE
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Tested to BS EN 13501-1 (Reaction to Fire)
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Achieves Euroclass B or Euroclass C depending on species and build-up
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Complies with UK Building Regulations – Document B (e.g. Class 0 or 1 equivalents)
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Fully suitable for HR (Humidity Resistant) and DI (Dry Internal) use
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Every consignment includes a Treatment Certificate and optional stamped items for traceability
Sentrin FRI is a lifetime fire retardant for internal timber, offering performance for the full life of the building or structure without the need for maintenance or reapplication—even in humid, but protected, interior environments.
THE PROCESS
Treatment Process
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Timber is placed in a sealed autoclave
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A vacuum removes air from the timber cells
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The vessel is flooded with warm fire retardant solution
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Pressure forces the solution deep into the wood
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A final vacuum removes excess liquid
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Timber is kiln-dried to its final moisture content
The full cycle takes 90 - 240 minutes, with drying and conditioning tailored to project requirements. No waste is produced in the process.
BENEFITS
Benefits at a Glance
Certified Fire Performance
Achieves Euroclass B or C ratings to reduce flame spread, smoke, and heat. Fully compliant with UK Building Regulations for interior safety.
Maintenance-Free, Lifetime Use
Designed to perform for the full service life of the building - no reapplication or inspection required under normal conditions.
Preserves Timber Integrity
The treatment does not affect strength, durability, or finish - ideal for load-bearing timber and visible joinery
Humidity Resistant
Formulated for performance in humid interiors (up to 85% RH), making it suitable for high-traffic or semi-moist environments like corridors or stairwells.
Handling, Fixings &
Storage
HANDLING
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Fixtures & Fixings: Sentrin FRI is non-corrosive to standard metal fittings
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Gluing: Compatible with most waterproof adhesives; avoid low-strength options like PVA
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Reworking: Cross-cutting is permitted, but no rip-sawing or planing (may expose untreated surfaces); sanding is acceptable
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Storage: Keep timber dry and protected from re-wetting. Exposure to rain will degrade fire performance
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Health & Safety: Treated timber should not be used in direct contact with food, water, or animal bedding