STS Construction Board TG4 18mm Thick Fibre Cement Acoustic Floorboard

• Floor build-ups requiring acoustic mass — used as the high-mass floor deck in acoustic floor systems, either as a single layer or in combination with acoustic underlay. At 1200kg/m³, TG4 adds substantially more surface mass per mm of thickness than chipboard (typically 600–700kg/m³) or plywood (500–600kg/m³), directly improving the airborne sound reduction of the floor assembly.
• Wet rooms, bathrooms, and kitchens — the cement-based composition is unaffected by moisture exposure, making TG4 suitable as a subfloor deck in wet areas where chipboard or OSB would swell, delaminate, or rot. Water absorption of 36% after 22 hours submersion confirms the material absorbs moisture without losing structural integrity or dimensional stability.
• Loft conversions — as a floor deck providing both acoustic performance and structural rigidity across existing ceiling joists. The Class A1 fire rating satisfies building regulations requirements for fire compartmentation in loft conversion floor builds.
• Flat roofs and mezzanine flooring — the dimensional stability and moisture resistance of the cement composition makes TG4 suitable for flat roof decking and elevated mezzanine floors where timber-based boards are vulnerable to movement from moisture cycling.
• New build and renovation — compatible with underfloor heating systems. The thermal conductivity of 0.172 W/m.K and U value of 0.1047 W/m²K confirm the board does not significantly impede heat transfer from underfloor heating to the floor surface.

• 1200kg/m³ density — high acoustic mass. The mass of a floor assembly is one of the primary determinants of airborne sound reduction. TG4 at 1200kg/m³ provides approximately twice the surface mass of chipboard at equivalent thickness, directly improving the acoustic performance of the floor build-up without requiring additional layers.
• Class A1 fire classification — non-combustible. Achieves the highest reaction to fire classification under EN 13501-1. TG4 will not contribute to the development or spread of fire, satisfying building regulations requirements for fire-rated floor assemblies in loft conversions, flats, and commercial buildings.
• Moisture resistant — dimensionally stable. Unlike chipboard and OSB, which swell, delaminate, and lose structural integrity when exposed to moisture, the cement composition of TG4 remains dimensionally stable. Suitable for permanent use in wet areas and external or semi-external applications where moisture exposure is unavoidable.
• Tongue and groove on all four sides. Four-sided T&G profiling interlocks boards in both directions, eliminating the need for noggins or additional edge support at every joint and providing a rigid, continuous floor surface across the installation.
• Compatible with underfloor heating. Thermal conductivity of 0.172 W/m.K ensures effective heat transfer from wet or electric underfloor heating systems through the board to the floor surface above.
• 100% recyclable. The cement and mineral composition is fully recyclable at end of life.

Cut SilentBoards using a circular saw fixed with a vacuum extractor and a PCD saw blade. This method will cut boards easily and mitigate dust. Boards are fixed with board text facing up.

2. Laying Boards In Place.

If the boards are being used with a floating floor system the boards should be loose laid on top of the R10 Acoustic Matting.

If the boards are being fixed directly onto timber or steel joists they should be a maximum of 600mm centre. To achieve an acceptable finish it is important that floor joists are level. We would recommend you also incorporate Green Glue Joist Tape to minimise squeaking.

3. Secure With Screws (Ignore this if fitting a Floating Floor System)

Secure with 12 x 50mm Fibre Cement Board Screws placed at a minimum of 12mm from the square edge and 5mm from the side of the joist. Ensure screws are placed a minimum distance of 25mm from the tongue and grove edge.

4. Apply Adhesive To The Grove.

Lay in a brick bond pattern. Tongue and grove joins do not need to end on a joist but all square edges should be fully supported. Secure subsequent boards by applying Mega Strength PU Adhesive along the length of the boards grove, before inserting the tongue of the next board. Ready to install finish surface immediately.

Floating Floor System

First ensure that the floor is completely clean, free of dirt and debris. Before you begin installation it is good practice to ensure that there are no loose floorboards. Loose boards can squeak and once the floating floor system has been fitted there won’t be any access to the floorboards. When screwing the floorboards down ensure that you will not screw through pipes or cables. You will also need to remove any existing skirting.

1. Seal any gaps in the existing floorboards with AC95 Acoustic Sealant. If there are holes that are too large for sealant repair the floor with replacement boards.

2. Lay the layer of Soundproofing mat on the floor in the direction perpendicular to the direction of the floorboards. Glue the soundproofing mat down using Advanced Acoustics Contact Adhesive to minimise ‘walking’ of materials. Lay the soundproofing mat right up to the wall. When laying the soundproofing may ensure there are no gaps between sheets.

3. Tape all the joints with Jointing Tape.

4. Run a 5mm thick, 25mm wide Resilient Sealing tape around the perimeter of the room at floor level. This will help to create a seal up to the wall and aid to minimise flanking sound.

5. Lay the R10 Acoustic Matting with the rubber side down. Lay the R10 perpendicular to the layer of soundproofing mat. Lay the R10 right up to the resilient sealing tape.

6. Tape all the joints with jointing tape.

7. Loose lay the SilentBoard straight onto the R10 with the writing side up. Lay in a brick bond fashion perpendicular to the layer of R10. The first row of boards should be butted up the resilient tape. Cut SilentBoards using a circular saw fixed with a vacuum extractor and a PCD saw blade. Secure subsequent boards by applying mega strength PU adhesive along the length of the boards grove, before inserting the tongue of the next board.

8. Using AC95 seal the perimeter of the floor.

9. You can now refit your skirting ensuring you leave a 2mm gap between the SilentBoard and the skirting.

10. Seal the gap with AC95 Acoustic Sealant.

11. You can now fit your finish floor covering.

Is the 22mm board always the better acoustic choice?

Thickness alone should not decide the purchase. Choose the board required by the support arrangement and floor specification, then consider the acoustic build-up as a whole. The 18mm option may suit a height-constrained system, but it should not replace a specified 22mm deck without checking suitability.

Can I replace chipboard with TG4 and expect it to solve footsteps?

TG4 adds a high-mass deck, but impact-noise control also depends on how the floor is separated from the structure. If footsteps are the main problem, consider a floating assembly rather than relying on a board substitution alone.

Can I screw the boards down to make the floor feel more secure?

If it is a floating-floor installation loose-lay the boards over the resilient layer and bond the tongue-and-groove joints with PU adhesive. Screwing through to the supporting floor would create rigid connections. Do not combine the direct-fix and floating-floor methods.

What should I check before ordering for an upstairs room?

Check the structural suitability, complete floor height and handling access. The listed board weights are 18.8kg for 18mm and 24.8kg for 22mm, so plan both the installed load and how the boards will reach the room.

Why is delivery charged on this product?

Due to the weight of this product, orders are shipped via a specialist freight company rather than standard parcel delivery. Delivery is still on a next-day service. For larger quantities, orders may be dispatched on a pallet. If you would prefer to collect, this option is available at the payment stage — our facility is located in Mansfield, Nottinghamshire.