STS TG4 Construction Board | Fibre Cement | 600mm x 1200mm x 18mm
STS TG4 is a fibre cement construction board composed of Portland cement, cellulose fibres, sand, water, and minor aggregates, manufactured to a density of 1200kg/m³. The high mass density is the primary acoustic property of the board — at 1200kg/m³, a single 18mm board weighs 18.8kg and presents significantly more resistance to airborne sound transmission than chipboard or plywood of equivalent thickness.
The cement-based composition also makes the board dimensionally stable in the presence of moisture, non-combustible to Class A1, and unaffected by rot, expansion, or shape change that causes long-term acoustic and structural problems with timber-based boards.
Tongue and groove profiling on all four edges allows boards to interlock on all sides, eliminating step joints at the board edges and providing a stable, continuous floor surface without the need for additional edge support at every joint. Compatible with metal, timber, and concrete substructures.
Minimum order is 10 boards due to shipping constraints.
Applications
- 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.
Product Benefits
- 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.
Installation
Store boards flat in dry conditions before installation. TG4 is a heavy board — at 18.8kg per board, two-person handling is recommended for overhead or large-scale installations. Cut using a diamond-tipped or carbide blade — standard wood-cutting blades will not cut fibre cement effectively and will wear rapidly. Lay boards with staggered joints and engage the tongue and groove on all four sides before fixing. Fix to the substructure using STS Mega Strength PU Adhesive and mechanical fixings appropriate to the substructure type. The high pH of the cement composition (10.4) means prolonged skin contact should be avoided during cutting and handling — wear gloves and a dust mask when cutting.
The Technical Details
| Product Name | STS TG4 Construction Board 18mm |
| Product Size | 1200mm x 600mm |
| Product Thickness | 18mm |
| Area Covered Per Board | 0.72sqm |
| Product Weight | 18.8kg |
| Density | 1200kg/m3 |
| Thickness Tolerance | +/- 5% |
| Dimension Tolerance | +/- 1mm |
| Weight Tolerance | +/- 5% |
| Modulus Of Rupture EMC - min | 10 MPa |
| Free Moisture Content | 6% |
| Water Absorption - submersion after 22 hours | 36% |
| Lamina Bond Strength | 0.9 MPa |
| Thermal Conductivity (K) (30° C Mean Temperature) | 0.172 W/M .k |
| pH Value | 10.4 |
| U Value | 0.1047 Wm2K |
| Fire Classification | Class A1 |
17%
13%
