Boards and mats in fire protection
Boards and roll materials are the “dry” form of non-reactive fire protection. They need no mixing or drying, they arrive on site with factory-controlled thickness and density, and the quality of the system depends mainly on correct cutting and fixing. This makes them convenient for refurbishment, for work in occupied buildings and in weather that rules out wet trades.
Main types
Calcium silicate boards
Rigid non-combustible boards with a cement or lime-silica binder and reinforcing fibres. They are strong and moisture-resistant, can be worked with ordinary tools and are fixed with screws or staples. They are used for box encasement of columns and beams, protective linings for concrete slabs and tunnels, self-supporting fire-resisting ductwork, cable enclosures and shafts. Boards of different densities serve different purposes: dense boards for encasing load-bearing structures and for areas exposed to impact, lightweight boards for enclosures and ductwork, where weight matters.
Mineral wool fire protection boards
Rigid high-density stone wool boards, sometimes faced with glass tissue or foil. They are bonded with a special fire-rated adhesive and/or fixed with pins. They provide thermal and acoustic insulation at the same time, which makes them popular for protecting ductwork and steelwork in concealed areas.
Wired mats and wraps
Stone or basalt wool mats stitched to galvanised wire mesh, and thin foil-faced roll materials made of inorganic fibres. They are wrapped around circular and rectangular ductwork, pipework and steel members of complex shape. Roll materials are useful where space is tight.
Plasterboard and gypsum fibre boards
Used in lining and partition systems; for fire protection, special grades with enhanced fire resistance are used. Their limitation is sensitivity to moisture.
How they work
Boards and mats form a passive insulating barrier. Some materials (calcium silicate, gypsum) contain bound water and so absorb additional heat as they warm up. Stone wool retains its fibrous structure at high temperatures and does not melt under standard fire conditions. The weak point of any board system is the joints and fixings: fire can bypass the board through a gap, which is why the manufacturer strictly specifies overlaps, fixing centres and joint sealing.
How to choose
- Element and purpose. Encasing load-bearing steel, protecting a concrete floor slab, a fire-resisting duct, a cable enclosure — for each task the manufacturer has its own system and its own thickness tables.
- Required fire resistance rating. R for load-bearing structures, EI for ductwork and enclosures. The number of layers and the board thickness are taken from the approved solution.
- Reduced metal thickness. With box encasement, the perimeter of the box rather than that of the section profile is taken into account — which often allows the thickness to be reduced.
- Humidity and aggressiveness of the environment. Calcium silicate and stone wool tolerate humidity better than gypsum, but external use requires special solutions.
- Mechanical exposure and accessibility. Where impact is possible, dense boards are chosen, or soft materials are protected with a lining.
- Complete system. Adhesive, fixings, sealants and joint seals are part of the tested system and must not be substituted at will.
Common mistakes
- Buying boards without the adhesive, fixings and sealant specified for the system.
- Gaps and poorly fitted joints, no overlap at corners.
- Mineral wool materials left unprotected from wetting on site.
- Replacing one manufacturer’s board with an “equivalent” of the same thickness without an approved solution.
- Breaching the encasement when running services and not making it good afterwards.
Materials from leading manufacturers
- PROMATECT-H — Promat — dense calcium silicate board for encasing steel, lining concrete, and for shafts and partitions.
- PROMATECT-L500 — Promat — lightweight calcium silicate board for fire-resisting ductwork and cable enclosures.
- ROCKWOOL Conlit 150 — ROCKWOOL — rigid stone wool board for fire protection of load-bearing structural steel.
- ROCKWOOL Conlit Ductrock — ROCKWOOL — board faced with reinforced foil, for rectangular ductwork.
- ROCKWOOL Conlit Fire Mat — ROCKWOOL — wired mat (stitched to wire mesh) for circular ductwork.
- 3M Fire Barrier Duct Wrap 615+ — 3M — thin inorganic fibre mat in roll form for ventilation and kitchen extract ducts.
- Nullifire FB750 Intubatt — Nullifire (Tremco CPG) — mineral wool board with a fire protection coating, for sealing penetrations.
- PROMATECT-100 — Promat — non-combustible calcium silicate board for fire-rated ceilings, walls, shafts and protective membranes.
- PROMATECT-200 — Promat — calcium silicate board for boxed fire protection of steel structures and cable ducts.
- PROMATECT-XS — Promat — non-combustible A1 board for encasing steel columns and beams, up to 60 minutes.
- ROCKWOOL Conlit Steelprotect Section — ROCKWOOL — stone wool fire protection sections for round steel columns and sprinkler pipes.
- PROMATECT-250 — Promat — calcium silicate board for fire protection casings of steel columns and beams, R15–R120.
- 3M Interam Endothermic Mat E-54A — 3M — endothermic wrap mat protecting structural steel, cables and cable trays.
Frequently asked questions
Why is calcium silicate better than plasterboard?
It is more resistant to moisture and mechanical damage, retains its properties in damp areas and can be used to build self-supporting enclosures and ductwork. Plasterboard is cheaper but limited to dry conditions.
Can mineral wool board be fixed with adhesive alone?
Only if the manufacturer’s approved solution allows it. Many systems combine adhesive with mechanical fixing, particularly on vertical surfaces and soffits.
Do the boards provide thermal insulation?
Mineral wool boards do, and this often solves two problems at once, for example on ductwork. Calcium silicate boards also reduce heat loss, but their main role is fire protection and strength.