Questions we are asked

Cement, silica sand, high-performance additives and cellulose fibre. It is cured in an autoclave — superheated steam at high pressure, which enhances the reaction between the cement and the silica. Cemtone states that this gives improved strength, lower moisture movement and high fire resistance.

Every sheet is 1220 × 2440 mm, in seven thicknesses: 6, 8, 9, 10, 12, 15 and 18 mm. Custom sizes can be manufactured for a specific project.

A full 1220 × 2440 mm sheet weighs 24 kg at 6 mm · 32 kg at 8 mm · 36 kg at 9 mm · 40 kg at 10 mm · 48 kg at 12 mm · 60 kg at 15 mm · 72 kg at 18 mm.

Per square metre that is 8.1 · 10.7 · 12.1 · 13.4 · 16.1 · 20.2 · 24.2 kg. Use the per-square-metre figure for a dead load, and the per-sheet figure for handling and delivery.

No. Gypsum board has a paper face and a gypsum core. Cemtone board is cement, silica sand and cellulose fibre, cured under pressure. We do not publish a side-by-side comparison, because we have not tested gypsum board ourselves.

No. A sample was independently tested to ISO 1182 and found non-combustible.

That is a result about the material, not a rating for a wall. A fire-rated wall or shaft is a complete assembly — board, framing, fixings, cavity and insulation — tested together for a period in minutes. If you need a period for a particular assembly, it has to come from a test of that assembly.

Yes. Use 9–12 mm as a wall underlay beneath ceramic tiles. The board passes five durability tests to BS EN 12467 — impermeability, freeze–thaw, heat–rain, warm water and soak–dry.

Add stud frames at every connection and hanging point, such as a basin or sanitary ware, and use tiles no larger than 600 × 600 mm.

It is water resistant, and it passed the BS EN 12467 impermeability test. That is not the same as a waterproof membrane. In a wet area the board is the substrate; the tiling and sealing system above it does the waterproofing.

No. Cemtone lists the board as termite proof. It is a cement-based sheet, not a timber one.

Interior wall 6, 8, 9 or 10 mm · internal wall underlay 8, 9, 10 or 12 mm · ceiling 6, 8 or 9 mm · external wall and facade 10, 12, 15 or 18 mm · external or internal floor 12, 15 or 18 mm · floor underlay 9, 10 or 12 mm · sub roof 9, 10, 12 or 15 mm · wet area under tile 9 or 12 mm.

Where a surface is exposed externally, our wall guidance suggests more than 12 mm, or as specified.

For walls, verticals at 400 ±10 mm to 600 ±10 mm and horizontals at 2440 mm, so the board meets the frame at its own end rather than at a cut. For floors, a 400 ±10 × 400 ±10 mm grid. For ceilings, 400 ±10 to 600 ±10 mm.

200–300 mm along a board edge and 300–400 mm in the field. Stay 75 mm clear of a corner and 30 mm clear of an edge. Drill pilot holes — do not punch them.

Yes — 2–3 mm, or a butt joint as the job requires. Cover the gaps with mesh tape, then fill gaps and screw holes with Cemtone putty.

On a frame for most uses: a 1.2 mm steel stud internally, or a 3 inch × 2.3 mm steel tube frame externally — galvanized or steel, as the project engineer specifies. Start the board 100 mm above floor level, to keep the board and the studs out of water.

Over an existing cement floor it is fixed directly, with concrete nails every 200 mm.

Yes. Clean with a damp cloth, apply at least one coat of primer, then 100% acrylic colour. For a gloss finish, apply semi-gloss acrylic or polyurethane at least twice.

The board is alkaline — pH 10 to 12 — which is normal for a cement product. Choose primers, sealants and adhesives rated for an alkaline substrate.

Yes. Clean the board with a damp cloth and apply Cemtone Sealer, or a bonding coat left 1–4 hours to set, then the tile adhesive. Tiles should be no larger than 600 × 600 mm.