RENDERING CEMENT BOARDS

Renders World supplies rendering cement boards to UK render contractors as a three-part substrate package — two board formats and the matched screw — inside the wider rendering materials range.

Which UK Builds Need a Render Carrier Board

Rendering cement boards carry thin-coat render on framed construction, and the STS NoMorePly sheet is manufactured to BS EN 12467:2016 + A1:2016 at 45 kg per 2,400 × 1,200 mm board — the substrate timber frame, light steel frame and SIP facades need.

The cavity governs all three: STS requires a ventilated void behind the board, open top and bottom, with a minimum 15 mm airflow gap where the boarding would otherwise finish flush with the wall below.

• Timber frame: breather membrane first, then vertical battens — the orientation STS recommends so the cavity vents.
• Light steel frame: SFS work takes a 4.8 × 38 mm wingtip screw rather than the 3.95 × 38 mm timber fixing.
• SIP panels: no internal studwork, so battens fix straight to the outer OSB at 400 or 600 mm centres, and moisture sequencing sits in the timber frame moisture and airtightness guide.

Why Specifiers Put Fibre Cement Behind a Thin-Coat Facade

• A declared minimum life: STS states 30 years minimum expected life against BS EN 12467:2016 + A1:2016, the standard a system designer asks to see.
• Fixing headroom in the sheet: mean 1,650 N pull-through and 840 N pull-out on the board itself, so light trim and clips land in the face while rails go back to the frame.
• No thermal pretence: 0.24149 W/mK with 0.0493 m²K/W declared resistance, so the sheet is worth almost nothing in a U-value — the insulation layer does that work.

Two figures stay off this page deliberately. No reaction-to-fire class is published for the render carrier board: the installation guide's A1 line names a differently named STS construction board, the 12 mm sheet datasheet declares A1 under its own heading, and the third document is the 1996 European list of materials treated as Class A without testing. Confirm the class with STS for your specific build-up, under current Approved Document B guidance. Density diverges too — 1.23 g/cm³ in the carrier guide against 1.28 g/cm³ on the board datasheet — so where a calculation turns on mass, ask which sheet governs the pallet delivered.

Choose Your Board Format and Fixing Pack

Renders World prices both rendering cement boards by the sheet, and the per-square-metre position favours the full format: £52.00 ÷ 2.88 m² = £18.06/m² against £18.80 ÷ 0.96 m² = £19.58/m², as displayed in August 2026. Order the small sheet for what it does well — reveals, dormers and infill — rather than on rate.

All three were in stock at the time of this fetch, and delivery is quoted per order: in-stock lines process the same day, pallets up to 1,200 kg move next day or two business days on the economy option, free within 15 miles of the Southampton base on orders over £300 and £1.50 per additional mile to 60 miles. Prices above are the figures displayed in August 2026 and the VAT position is not stated in the fields read, so confirm it on the order.

How to Fit the Boards, Then Render Over Them

The STS sequence runs frame, battens, board, primer, basecoat with mesh embedded, then render finish — and the fixing schedule is a count per sheet rather than a spacing to eyeball.

1. Batten out: vertical battens at 600 mm centres, or 400 mm on exposed high wind-load elevations, minimum 60 × 25 mm. Scotland, Northern Ireland and the Republic of Ireland work to a 50 mm minimum cavity depth.
2. Set out: a 3–5 mm gap on all sides, joints staggered, and no board joint running out from a window or door edge — cut around the opening onto a 25 × 60 mm batten.
3. Fix: 3.95 × 38 mm self-drilling, self-countersinking screws into timber, 20 mm in from edges, at 27 per full sheet on 600 mm battens and 28 on 400 mm battens.
4. Reinforce: prime, then bed mesh into the basecoat across every joint, doubling it at opening corners as most render manufacturers ask.

Movement joints belong in the design: STS puts them at 15 m maximum spans or on the substrate's own joints, the gap itself no wider than 25 mm, agreed with the render manufacturer, architect or building control. The worked sequence sits in the cement board rendering guide, the priming coat in our exterior render primers, the bedding layer in the EPS adhesives basecoats range, and reveal sequencing in the window and door detailing guide.

Site Notes From UK Render Crews

Three things the STS guide answers that a takeoff sheet usually does not.

• The two-month rule beats a tarpaulin: boards stand exposed for up to six months, but where render is more than two months off, STS wants PU adhesive between the boards at install, or external-grade filler and weatherproof tape on the joints later.
• Buy screws by sheet count: 250 ÷ 27 fixings per sheet = 9 boards per box, about £1.39 of STS render board screws per sheet, so one box per nine boards plus a spare covers edge replacements.
• Plan the drop: a 45 kg sheet sits past the 25 kg parcel band, so boards arrive on a pallet, kerbside, wrapped but not weatherproof.

Deciding Whether the Range Suits Your Build-Up

• Framed new build with render: the core case — board, batten and matched screw give the system a plane that holds still.
• Thin-coat finish to follow: STS advises a flexible system over sand and cement, which is where thin-coat silicone render takes the elevation on.
• Insulation in the same build-up: our insulation fixing accessories cover the plugs, anchors and base tracks.
• Warranty-inspected housing: board fixing and joint detailing are inspection points, covered in the NHBC render detailing guide.
• Solid masonry: a different route — render onto primed masonry needs no carrier board at all.

Renders World stocks all three lines together: take the 2.4 × 1.2 m carrier board for the open elevations and add the half sheet for detail areas.

FAQ — Cavity Depth, Fixing Counts and Ordering

How many screws does one board take?

Twenty-seven per 2,400 × 1,200 mm sheet on battens at 600 mm centres, or 28 on 400 mm centres. A 250-piece box of 38 mm render board screws therefore covers nine full sheets.

How long can the boards stay exposed before rendering?

Up to six months. Past two months, STS asks for PU adhesive between boards at install, or an external-grade joint filler and weatherproof tape afterwards, and the boards must be dry, dust-free and undamaged before render goes on.

Can sand and cement render go over these boards?

STS recommends a flexible thin-coat silicone system instead. Cement sets completely solid, and a joint that moves slightly is better bridged by a flexible finish over mesh — which is why the reinforced thin-coat build-up is the specification here.

Does the required cavity depth differ across the UK?

Yes. England and Wales work to the batten depth, commonly 60 × 25 mm, while Scotland, Northern Ireland and the Republic of Ireland take a 50 mm minimum cavity depth. Confirm the membrane and cavity with building control or the project engineer.