Description
Use the STS NoMorePly 12mm fibre cement board (2.4 m × 1.2 m) as a high-strength, A1 non-combustible render carrier wherever the substrate cannot accept render directly — timber frame, SIPs, steel frame, or external soffits. Supplied as a full sheet from our render carrier boards collection, this 45 kg board meets BS EN 12467:2016 + A1:2016 and provides a dimensionally stable face for thin-coat silicone, mineral, and acrylic systems.
Product Overview
The 2400 × 1200 × 12 mm fibre cement board is the standard render-carrier format on UK timber-frame and steel-frame facades, delivering a Class A1 non-combustible substrate at a measured density of 1.28 g/cm³. The full-sheet format reduces joint count compared with the half-size 1.2 × 0.8 m board, which matters on tall elevations where every additional joint becomes a basecoat reinforcement task.
Bending strength is rated at 12.46 MPa dry and 12.91 MPa after warm-water saturation — the saturated value is the one to read carefully, because it confirms the board does not soften when wetted by basecoat or driving rain. Pull-through resistance averages 1,650 N at the screw, which is why STS render board screws transfer load reliably into the carrier without the washer pulling through.
Key Benefits
- Class A1 non-combustible — tested to EN 13501-1, EN ISO 1182 and EN ISO 1716, suitable for facades where the project fire strategy requires non-combustible build-up.
- Dimensionally stable across moisture cycles — linear variation of 0.16% means joints stay tight after basecoat application, reducing reflective cracking.
- Render-ready face when primed — primed water impermeability shows no damp patch after 192 hours, giving basecoat consistent suction.
- Heavy-duty fixing performance — 1,650 N mean pull-through and 840 N pull-out values support direct fixing of cabinets, sills, and ancillary trims.
- Full BS EN 12467 compliance — Category A, Class 2 mechanical (MOR), with verified freeze-thaw, heat-rain, warm-water and soak-dry durability.
Technical Specifications
| Property | Value |
|---|---|
| Dimensions | 2400 × 1200 × 12 mm |
| Board weight | 45 kg (±2%) |
| Density | 1.28 g/cm³ |
| Bending strength (dry / saturated) | 12.46 MPa / 12.91 MPa |
| Compression strength | 14.42 MPa |
| Linear variation (moisture) | 0.16% |
| Thermal conductivity (λ) | 0.241 W/mK |
| Reaction to fire | Euro Class A1 (non-combustible) |
| Pull-through / pull-out (mean) | 1,650 N / 840 N |
| Standard | BS EN 12467:2016 + A1:2016 |
Application & Compatibility
The 12 mm carrier works best on timber-frame and metal-frame walls where the sheathing layer needs to support a thin-coat render directly, on EWI build-ups requiring a non-combustible carrier behind the insulation, and on internal wet-room rendering. Joints should be staggered, screwed to studs at 200 mm centres on perimeters and 300 mm in the field, then taped and basecoated with a fibre-enhanced adhesive embedded with 100 mm mesh overlap across every joint.
For specification, fixing pattern, and render compatibility detail, the cement boards for rendering UK guide walks through carrier selection, joint treatment, and primer choice for thin-coat silicone systems.
Installation Notes
Fix with STS 38 mm render board screws — these are the matched fastener and deliver the published 1,650 N pull-through value. Drive flush with the board face, never countersunk, so the basecoat layer can bridge cleanly without dimples telegraphing through the finish coat. Where the carrier sits within an insulated build-up, additional EWI mechanical fixings may be required to anchor the assembly back to the structural wall — confirm the spacing schedule against the system designer's drawing.
For the cleanest joint result, leave a 3–4 mm gap between boards, fill with a flexible cementitious adhesive, and embed mesh while the adhesive is still wet. Prime the full surface with a quartz primer before render to equalise suction, particularly across taped joints where the adhesive absorbs differently from the board face.
Trade Insight
On tall elevations, the 2.4 × 1.2 m sheet keeps joint count down, but the 45 kg weight means two-person handling on scaffolds is the realistic working assumption. For dormer cheeks, soffit returns, and small reveal panels where the full sheet is wasteful, the smaller 1.2 × 0.8 m carrier board cuts material loss and is easier to manoeuvre into tight access. Plan the cutting schedule before delivery so off-cuts from the full sheets are graded for verge and reveal use rather than skipped.
Is This Product Right for Your Project?
- Render carrier on timber-frame walls: ideal — full sheet covers a stud bay run with minimum joints.
- Smaller panels, dormers, or reveals: consider the half-size 1.2 × 0.8 m board — lower waste, easier handling.
- EWI on solid masonry: a carrier board is rarely needed — render directly onto basecoated insulation in most cases.
- Fire-strategy-driven facades: the A1 classification supports non-combustible build-ups where the project fire strategy requires it.
Frequently Asked Questions
Is the 12 mm board genuinely Class A1?
Yes — tested to EN 13501-1 with supporting EN ISO 1182 and EN ISO 1716 results, the board is classified Euro Class A1 non-combustible. This makes it suitable as a render carrier within build-ups where the fire strategy specifies non-combustible materials, subject to current Approved Document B guidance.
How many screws per board?
Typical fixing pattern is 200 mm centres on board perimeters and 300 mm in the field, giving roughly 30–35 screws per 2.88 m² sheet on stud framing. Always cross-reference the system designer's spacing schedule for the specific facade build-up.
Do I need to prime before rendering?
Yes. Quartz primer equalises suction between the board face and the basecoated joints, which delivers a more uniform render finish. The TDS confirms primed water impermeability remains intact after 192 hours of test exposure.
How heavy is one sheet?
45 kg per board (±2% tolerance). Plan two-person handling, especially at height — see the cement board rendering guide for site-handling recommendations.
Technical Documentation