Description
Fixing 12 mm fibre-cement carrier boards to a timber or steel frame calls for a fastener built for the alkaline zone behind a cement basecoat, where a standard zinc-plated screw can corrode within two to three years. The STS 38 mm render board screw answers that with a Ruspert zinc-aluminium-ceramic coating, a flush conical head, and 25 mm minimum frame embedment — supplied 250 to a trade box.
Where STS Render Board Screws Perform Best — UK Applications
The STS 38 mm render board screw fixes 12 mm fibre-cement carrier boards to timber and light-gauge steel framing on external render and EWI facades, driving through the full board thickness to reach a 25 mm minimum embedment in the frame behind. That embedment is what delivers the pull-through resistance a fully rendered 45 kg panel needs under UK wind load and thermal cycling. Supplied through the Renders World rendering cement boards range, it is the matched fastener for the carrier-board system rather than a general-purpose fixing adapted to the job.
The screw suits three settings cleanly: external rendered facades on frame construction, internal wet-room and tile-backer installations on 12 mm fibre-cement board, and steel-frame builds up to roughly 1.2 mm gauge where the self-drilling tip bites without a pilot hole. Get the fastener right and the render finish behind stays clean for the working life of the facade.
Why Trade Specifiers Choose STS Render Board Screws
- Ruspert corrosion protection for the basecoat zone: the zinc-aluminium-ceramic multi-layer coating references ASTM B117 / DIN 50018 salt-spray performance and holds up in the sustained high-pH contact zone behind a cement basecoat, preventing the rust bleed-through that ends the service life of standard zinc-plated fixings.
- Flush conical countersunk head: the 7 mm head seats level with the board face once driven, leaving a flat plane for basecoat and mesh so no screw head telegraphs through the render topcoat.
- Length engineered for 12 mm board: 38 mm gives full board penetration plus the 25 mm minimum frame embedment that pull-through calculations require for a rendered fibre-cement panel under wind load.
- Self-drilling tip for light-gauge steel: drives directly into steel channels up to around 1.2 mm gauge without a pilot hole, suiting the prefabricated steel-stud systems common across UK facade work.
- 250-piece trade box: covers roughly 6–8 m² of board area at standard fixing centres, letting the order schedule match measured board quantities without over-ordering.
Technical Specifications — STS Render Board Screws Data Sheet Highlights
| Property | Value |
|---|---|
| Screw length | 38 mm |
| Head type | Conical countersunk, flush finish · 7 mm head diameter |
| Major / minor diameter | 3.95 mm / 2.68 mm |
| Coating | Ruspert zinc-aluminium-ceramic multi-layer |
| Quantity per box | 250 pcs |
| Board compatibility | STS / NoMorePly 12 mm fibre-cement carrier board |
| Minimum frame embedment | 25 mm into timber stud or light-gauge steel channel |
| Substrate suitability | Timber stud · light-gauge steel up to ~1.2 mm gauge |
| Approx. coverage per box | 6–8 m² at standard fixing centres |
| Corrosion reference | Ruspert performance referenced to ASTM B117 / DIN 50018 salt-spray testing |
How to Apply STS Render Board Screws — Fixing Centres, Depth Setting, Coverage
Drive screws at the centres the board manufacturer specifies — typically 200–300 mm around the board perimeter and 300 mm on intermediate studs. A depth-setting attachment on the drill driver lands every head precisely flush: over-driving fractures the fibre-cement matrix around the head and creates a weak point beneath the render, while under-driving leaves a proud head that disrupts basecoat flatness.
These screws are the matched fixing for both the STS full-size render board and the half-size board, which share the same 12 mm thickness and fixing schedule, so one screw specification covers both formats. For the full board installation sequence — layout, cutting patterns, expansion-gap detailing, and basecoat integration — the cement boards for rendering guide walks through the worked process.
Installation Notes — Edge Distance, Steel Gauge, and Site Storage
For the best result, pre-drill pilot holes where screw positions fall within 15 mm of a board edge. Fibre cement is brittle at close edge distances, and driving without a pilot risks splitting a narrow strip. Beyond 15 mm from any edge, the thread cuts cleanly into the board matrix at standard drill-driver speeds with no pilot needed.
On light-gauge steel, confirm gauge before committing to a fixing pattern: the self-drilling tip penetrates channels up to around 1.2 mm cleanly, and heavier sections benefit from a pre-drilled clearance hole first. Store boxes closed in a dry location — the Ruspert coating performs reliably once a screw is installed, and keeping unfixed screws out of standing water keeps them in first-class condition until they go in. Where insulation boards form part of the substrate build-up, the insulation fixing accessories range supplies the dedicated plugs and anchors that suit EPS and mineral-wool boards.
Pro Tips From UK Installers Using STS Render Board Screws
- Calculate pack count from board count: a 2.4 m × 1.2 m board on studs at 600 mm centres with 200 mm perimeter fixings takes roughly 35–40 screws, so one 250-piece box covers six to seven boards. Order one box per six boards, add 10% for edge replacements, and the pack count lands first time.
- Set the depth attachment on a sacrificial board first: dial in the flush depth before working the elevation proper, and the whole panel pulls level under basecoat instead of telegraphing screw heads through the topcoat.
- Keep the matched fastener in the specification: the alkaline zone behind a cement basecoat is exactly the exposure Ruspert is formulated for, and the per-screw cost is trivial against facade remediation — so the corrosion-rated screw is the confident choice every time.
- Verify steel gauge at survey stage: a 1.2 mm ceiling covers most UK light-gauge systems, but flag heavier prefabricated frames early so pre-drilling is planned into the programme rather than discovered on day one.
Is the STS 38 mm Render Board Screw Right for Your Project?
- Fixing STS or NoMorePly 12 mm boards for external render: the system-matched fastener, with flush head, Ruspert protection, and embedment calibrated for 12 mm board pull-through under wind load.
- Internal wet-room and tile-backer board work: the same corrosion resistance holds up behind tile adhesive and waterproofing membranes in bathrooms, wet rooms, and pool surrounds.
- Insulation-board fixing for EWI: a different product family — for EPS, graphite EPS, or mineral-wool boards, the fixing accessories range covers the dedicated mechanical fixings and base tracks.
- Masonry substrates with direct render: not applicable where render goes straight onto masonry without a carrier board; the Renders World rendering menu covers that primer-and-basecoat route.
FAQ — STS Render Board Screw Coverage, Compatibility, Ordering
How many screws do I need per board?
A full 2.4 m × 1.2 m board fixed to timber studs at 600 mm centres with perimeter fixings at 200 mm takes approximately 35–40 screws. One 250-piece box covers roughly six to seven full boards, so the working ratio is one box per six boards plus 10% contingency. On half-size boards, screw count drops to around 12–15 per board.
Can these screws be used on steel framing?
The self-drilling tip penetrates light-gauge steel channels up to around 1.2 mm thickness directly, without a pilot hole. For heavier sections, pre-drill a clearance hole through the steel first, then drive the screw through the board into the frame. Confirming gauge at specification stage keeps the fixing pattern matched to the substrate.
What makes the Ruspert coating better than standard galvanising?
Ruspert is a multi-layer zinc-aluminium-ceramic system that outperforms single-layer zinc plating in alkaline, moisture-rich conditions. Behind a cement basecoat, the high-pH contact zone drives corrosion on standard zinc-plated screws, and the resulting rust can bleed through the topcoat within two to three years. Ruspert resists that exposure, referencing ASTM B117 / DIN 50018 salt-spray performance and holding clamping force across the render system's working life.
Do the screws need pre-drilling into the board?
Pre-drilling is needed only where positions fall within 15 mm of a board edge, to prevent splitting along the close-edge fibre line. Everywhere else the thread cuts cleanly at standard drill-driver speed. A depth-setting attachment lands every head flush, giving the basecoat the level plane it needs to pull true.
Can I use general-purpose wood or drywall screws instead?
Substituting standard zinc-plated fasteners is best avoided. The alkaline environment behind a cement basecoat accelerates corrosion on generic fixings, and rust streaks through the topcoat within two to three years are an invasive repair. The Ruspert coating is formulated for exactly this exposure, so specifying the matched screw protects the finish for the long term.
How should the screws be stored on site?
Keep boxes closed in a dry location. The coating performs reliably once a screw is driven into a sealed installation; keeping unfixed screws out of prolonged standing water keeps them in first-class condition, and a sealed box on a dry shelf in the compound is all it takes.
Technical Documentation — STS Render Board Screws TDS