Description
Supplied within our rendering cement boards range, the STS 38 mm render board screws are the system-matched fixing for STS and NoMorePly 12 mm fibre-cement carrier boards on timber-frame and light-gauge steel-frame render systems. Each trade box holds 250 screws with a Ruspert multi-layer zinc-aluminium-ceramic coating engineered to hold its corrosion resistance behind the alkaline cement basecoat zone where standard zinc-plated fasteners typically fail within 2–3 years. Stocked for trade collection or next-day UK dispatch from our Southampton warehouse.
What STS Render Board Screws Do in a Fibre-Cement Render Substrate
The STS 38 mm render board screw is purpose-designed for fixing 12 mm fibre-cement carrier boards to timber and light-gauge steel framing in external render and EWI applications. At 38 mm length, the screw penetrates the full 12 mm board thickness and achieves a minimum 25 mm embedment into the timber stud or steel channel behind, providing the pull-through resistance needed to hold a board weighing up to 45 kg securely against wind load and thermal-cycling forces on an exposed facade.
The Ruspert coating is a multi-layer zinc-aluminium-ceramic finish that outperforms standard galvanising in alkaline environments — meaningful because the cement-based basecoat applied over the board creates a sustained high-pH contact zone around every screw head. Standard zinc-plated screws can corrode and stain within 2–3 years behind a render system; the Ruspert finish is the engineered response to that exposure condition and maintains full clamping force across the working life of the facade.
What Makes the STS 38 mm Ruspert-Coated Screw Worth Specifying
- Ruspert multi-layer corrosion protection: the zinc-aluminium-ceramic coating delivers ASTM B117 / DIN 50018 corrosion-resistance performance in the alkaline basecoat zone, preventing the rust-staining bleed-through that costs typical zinc-plated fixings their service life behind render.
- Conical countersunk head for flush finish: the head profile seats flush with the board face once driven, leaving a flat plane for basecoat and mesh — proud screw heads telegraph through the render finish, and the countersunk profile eliminates that defect at source.
- Engineered length for 12 mm board substrates: 38 mm gives full board penetration plus the 25 mm minimum embedment that pull-through resistance calculations require for a fully rendered 45 kg fibre-cement panel under wind load.
- System-matched to STS and NoMorePly boards: thread profile, head geometry, and torque characteristics are tested specifically for the density and composition of 12 mm fibre-cement construction board rather than adapted from general-purpose fixings.
- 250-piece trade box: covers roughly 6–8 m² of board area at standard fixing centres — a practical pack quantity that reduces site waste and lets the order schedule match measured board quantities cleanly.
- Self-drilling tip for light-gauge steel: the tip drives directly into steel channels up to approximately 1.2 mm gauge without a pilot hole, suiting the prefabricated steel-stud constructions used across UK light-gauge facade systems.
Technical Specifications — STS Render Board Screws Data
| Property | Value |
|---|---|
| Screw length | 38 mm |
| Head type | Conical countersunk — flush finish |
| Coating | Ruspert (zinc-aluminium-ceramic multi-layer) |
| Quantity per box | 250 pcs |
| Board compatibility | STS / NoMorePly 12 mm fibre-cement carrier board |
| Minimum embedment in framing | 25 mm into timber stud or light-gauge steel channel |
| Substrate suitability | Timber stud · light-gauge steel up to ~1.2 mm gauge |
| Approximate coverage per box | 6–8 m² at standard fixing centres |
| Approximate screws per full board | 35–40 per 2.4 m × 1.2 m board (timber studs at 600 mm centres, perimeter at 200 mm) |
| Corrosion-resistance reference | Ruspert performance referenced against ASTM B117 / DIN 50018 neutral salt-spray testing |
How STS Render Board Screws Install Into STS 12 mm Carrier Boards
Drive screws at the fixing centres specified by the board manufacturer — typically 200–300 mm around the board perimeter and 300 mm on intermediate studs. Use a depth-setting attachment on the drill driver so every head sits precisely flush with the board face: over-driving cracks the fibre-cement matrix locally around the head and creates a weak point beneath the render, while under-driving leaves a proud head that disrupts the basecoat flatness across the panel.
These screws are the matched fixing for the STS full-size render board and the half-size variant — both share the same 12 mm thickness and the same fixing schedule, so the screws cover both formats without separate SKU planning. For the complete board installation sequence — layout planning, cutting patterns, fixing centres, expansion-gap detailing, and basecoat integration — the cement boards for rendering guide walks through the worked process. For projects where insulation boards rather than fibre-cement boards form part of the substrate build-up, the insulation fixing accessories range covers the dedicated plugs, anchors, and base tracks that suit EPS, graphite EPS, and mineral-wool board fixing.
Installation Notes — Edge Distance, Depth Setting, Steel-Gauge Limits
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 hole risks splitting a narrow strip that then requires board replacement. At positions further than 15 mm from any edge, the screw thread cuts cleanly into the board matrix at standard drill-driver speeds, no pilot needed.
On light-gauge steel framing, confirm steel thickness before committing to a fixing pattern — the self-drilling tip penetrates channels up to approximately 1.2 mm gauge cleanly, and heavier sections require a pre-drilled clearance hole through the steel before driving the screw through the board and into the frame behind. Store boxes in a dry location on site: the Ruspert coating performs reliably once the screw is installed, but boxes left open and exposed to standing water can develop surface discolouration on the unfixed screws — cosmetically poor, though it does not affect the structural performance of screws once driven.
What UK Installers Do Differently With STS Render Board Screws
- Calculate pack count from board count, not linear metres: a standard 2.4 m × 1.2 m board at 600 mm stud 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 as a working ratio, add a 10% contingency for edge replacements and misdrives, and the pack count lands first time.
- Set the depth attachment once at the start: dial in the depth on a sacrificial board before working on the elevation proper. A consistent flush finish across the panel is the difference between a basecoat that pulls level cleanly and one that telegraphs every screw head through the topcoat.
- Resist the temptation to substitute general-purpose screws: the alkaline contact zone behind a cement basecoat will corrode standard zinc-plated wood screws or drywall screws within 2–3 years, and rust streaks bleeding through the render are an invasive repair to put right. The Ruspert coating is specifically formulated for this exposure — the price difference per screw is trivial against the cost of facade remediation.
- Stage screws to the lift sequence: on storey-height work, two boxes at scaffold level cover most lifts cleanly without runs back to the storage compound — pre-position the boxes on each lift before boards go up rather than carrying packs back and forth.
- Verify steel gauge at specification stage: a 1.2 mm gauge ceiling covers most light-gauge UK facade systems, but heavier prefabricated frames need pre-drilling planned into the programme rather than discovered on day one — flag this in the early survey for steel-frame projects.
Is the STS 38 mm Render Board Screw Right for Your Project?
- Fixing STS or NoMorePly 12 mm fibre-cement boards for external render: the system-matched fastener — flush countersunk head, Ruspert corrosion protection, length and embedment calibrated for 12 mm board pull-through resistance under wind load.
- Internal wet-room and tile-backer board installations: the same screws suit internal applications where 12 mm fibre-cement board serves as tile backer in bathrooms, wet rooms, and pool surrounds — Ruspert corrosion protection holds up behind tile adhesive and waterproofing membranes equally well.
- Steel-frame builds up to 1.2 mm gauge: the self-drilling tip handles light-gauge steel channels directly, with pre-drilling reserved for heavier prefabricated steel sections where the gauge exceeds the screw's rated capacity.
- Insulation-board fixing for EWI: not the right product family — for fixing EPS, graphite EPS, or mineral-wool boards in EWI systems, the insulation fixing accessories range covers the dedicated mechanical fixings, base tracks, and spiral anchors purpose-built for insulation substrates.
- Masonry substrates with direct render: not applicable where render goes directly onto a masonry substrate without a carrier-board layer — the screw is a board-fixing component, not a render-system component on solid wall builds.
FAQ — STS Render Board Screw Coverage, Compatibility, Ordering
How many screws do I need per board?
A full 2.4 m × 1.2 m fibre-cement board fixed to timber studs at 600 mm centres with perimeter fixings at 200 mm requires approximately 35–40 screws. One 250-piece box covers roughly six to seven full boards, so the working ratio for ordering is one box per six boards plus a 10% contingency for edge replacements and misdrives. On half-size boards (1.2 m × 0.8 m), screw count drops proportionally to roughly 12–15 per board.
Can these screws be used on steel framing?
The self-drilling tip penetrates light-gauge steel channels up to approximately 1.2 mm thickness directly, without a pilot hole. For heavier steel sections, pre-drill a clearance hole through the steel before driving the screw through the board and into the frame. Confirm the steel gauge at specification stage so the fixing pattern matches the substrate — discovering a heavier-than-rated section on day one of the install adds significant time to the programme.
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 and moisture-rich environments. Behind a cement-based basecoat, the sustained high-pH contact zone accelerates corrosion on standard zinc-plated screws, and the resulting rust can bleed through the render topcoat as visible staining within 2–3 years. Ruspert is engineered to resist that chemical exposure — the coating references ASTM B117 / DIN 50018 neutral salt-spray performance and holds clamping force across the working life of the render system.
Do the screws require pre-drilling into the fibre-cement board?
Pre-drilling is needed only where screw positions fall within 15 mm of a board edge to prevent splitting along the close-edge fibre line. At all other positions, the screw thread cuts cleanly into the board matrix at standard drill-driver speeds without a pilot hole. Use a depth-setting attachment on the driver to land every head flush with the board face — that is the consistent finish basecoat needs to pull level across the panel.
Can I use general-purpose wood screws or drywall screws instead?
Substituting standard zinc-plated fasteners is not advisable. The alkaline environment behind a cement-based basecoat accelerates corrosion on generic fixings, and rust streaks bleeding through the render topcoat within 2–3 years are an invasive cosmetic repair to remediate. The Ruspert coating on the STS screws is specifically formulated for this exposure — the per-screw cost difference against the remediation cost makes this an obvious specification choice.
How should the screws be stored on site before use?
Store boxes in a dry location with the lid closed. The Ruspert coating performs reliably once the screw is driven into a sealed installation, but unfixed screws exposed to prolonged standing water in an open box can develop a surface discolouration that — while cosmetically unappealing — does not affect the structural or corrosion performance of the screw once installed. A sealed plastic box on a dry shelf in the storage compound avoids the issue entirely.
Technical Documentation — STS Render Board Screws Datasheet