RENDERING

This silo covers the render side of a UK facade: the board or primer that starts the wall, the layers that bond and reinforce it, and the finish that weathers it. The insulation and detailing silos sit alongside it, one click away on the Renders World home page.

Which Layers a UK Render Specification Actually Buys

UK rendering materials suppliers stock a sequence rather than a shelf, and the Atlas thin-coat finish at the top of it declares V2 vapour permeability and 0.35 MPa adhesion to EN 15824:2017 — figures the layers beneath it must support. Each layer is bought against the one below, which is why the substrate decision comes before the colour one.

Three questions settle almost every specification in this silo, and the answers point at different collections rather than different brands.

• What is the wall made of? Masonry and concrete take a key coat straight away; timber and light steel frame need a carrier board first, on a vented cavity.
• Is insulation being added? That brings the adhesive, the boards and the mechanical fixings into the order, and it is the EWI silo that owns those.
• What does the elevation need to look like? Thin-coat silicone, mosaic on the plinth, or a concrete and timber effect — the finish sets the key coat and the tinting route behind it.

Browse the Rendering Range in Build-Up Order

Eleven collections make up this silo. Listed in the order a wall receives them, a long directory turns into a short shopping list.

1. Render colour charts and catalogues — settle the shade against a physical reference before anything is tinted.
2. Rendering cement boards — build the render substrate on timber, light steel frame or modular construction.
3. Fibre-enhanced EPS adhesives basecoats — bond the insulation and form the mesh-reinforced layer.
4. Matched exterior render primers — regulate substrate suction and key the surface for the finish.
5. Premium silicone render — the weather-facing decorative coat.
6. Mosaic renders for plinths — the splash-zone finish below the main elevation.
7. Concrete effect renders, stencils and sealers — cast-concrete and timber-look decorative routes.
8. Window sill extensions and over-sills — restore the drainage overhang lost to added wall thickness.
9. Power floats and render sponges — the floating and texturing tools for large elevations.
10. Silicone masonry paints — the overpainting route for an aged but sound facade.
11. Facade cleaning products — biological, resin and cement contamination on finished render.

Choose Your Route — Collection by Project Stage

The Renders World table below is sorted on position in the build-up, first layer to last, because that is where a buyer actually is when they arrive. Find the stage your project has reached, then follow the collection name.

Why a Facade Order Is Worth Consolidating

What separates rendering materials suppliers from a general builders' merchant is that the layers are sold as a tested sequence rather than as unrelated lines. Six things follow from that, and they show up on programmes where the scaffold is already booked.

• Assessment belongs to the assembly, not the tub. The Atlas render sheet lists the finish as a component of eight named systems under ITB-KOT assessments and three European Technical Assessments, and the Ceresit CT 16 sheet lists a separate ETA per Ceretherm system. Buying within one system keeps that documentation intact.
• The seasoning clock is part of the order. A reinforced layer made with Atlas Stopter K-100, Stopter K-50 or Hoter U2-B needs 3 days before render; concrete needs 28 days at structural moisture below 4 %. Sequencing the delivery to that beats stacking pallets on site.
• Key coats are specified by the finish above them. The Atlas sheet names Silkon ANX or Cerplast as the plaster base on concrete and cement plaster, and states that no plaster base is required over its own reinforced layers.
• Colour is tinted here, not ordered in. Renders World mixes to order on separate Atlas and Ceresit machines, across more than 1,000 available colours beyond the printed palettes, and will match another manufacturer's shade from a reference where a job has run short.
• One manufacture date per elevation. The Atlas sheet asks for render of the same manufacture date on one surface to avoid shade variation, which makes booking the whole facade in a single order a specification point rather than a convenience.
• Next-day UK-wide delivery. This is a site-wide delivery arrangement rather than a stock promise attached to any individual line.

What One Data Sheet Names Across Five Collections

The most useful routing map in this silo is not a category menu — it is the substrate section of the Atlas thin-coat sheet, which names products from five different collections by name. Reading it once answers most of the questions a hub page normally guesses at.

• Before any repair, the sheet primes the substrate with Atlas Uni-Grunt and fills unevenness with Atlas ZW 330 or an adhesive mortar for the reinforced layer.
• Where biological growth is present, it removes mould, decay fungi and algae with Atlas Mykos Plus before the wall is primed at all — which puts a cleaning consumable at the start of a new render job, not only at the end of an old one.
• For set material on tools, it names Atlas Resin Away for residues that clean water will not shift.
• For an aged facade, renovation runs through Atlas Salta N silicone paint rather than a second render coat.
• Below 5 °C, work above 0 °C is possible after the addition of Atlas Eskimo, which is an Atlas component and not a Ceresit one.

Where These Materials Land on UK Projects

Domestic retrofit, new-build housing and commercial refurbishment draw on the same portfolio and weight it differently. The guides below take each decision further than a hub page usefully can.

Choosing the Finish and the Binder

Topcoat selection sets the appearance and the maintenance cycle for two decades, so it rewards more than a glance at the palette. The ranked buying guide for UK thin-coat finishes works through exposure, certification and budget, while the silicone and acrylic binder comparison settles the question underneath it, since several ranges are dispersions carrying both resins.

Getting It on the Wall and Keeping It There

Method and preparation account for most of what goes right. The pillar on thin-coat render application, step by step follows the sequence a crew actually builds, the primer comparison for thin-coat systems separates penetrating primers from quartz key coats, and render cracking causes and prevention traces movement faults back through basecoat and mesh. Everything is indexed by cluster in the rendering and insulation knowledge hub.

Specifier Notes to Settle Before the Order Goes In

Five points come off the documents rather than off a price list, and each one changes a quantity or a sequence.

• Cavity depth is not a UK-wide figure. The STS carrier board guide gives a typical 60 mm wide by 25 mm deep batten for England and Wales, and a minimum 50 mm cavity depth for Scotland, Northern Ireland and the Republic of Ireland. Confirm the nation before the batten is ordered.
• Batten centres follow exposure. The same guide sets 600 mm centres as suitable in most cases and 400 mm centres where wind load or exposure is higher, which changes the fixing count per sheet from 27 to 28.
• Boards need a planned gap and a vent. A 3–5 mm gap on all sides absorbs frame movement, and the cavity must be vented top and bottom, with a minimum 15 mm airflow gap where the boards sit flush with the wall below.
• Board exposure has a window. The guide allows the board to stand exposed for up to 6 months, but asks for a PU adhesive between boards at install where rendering will not happen within two months.
• Primer colour is a specification, not a preference. The CT 16 sheet recommends the priming paint in the colour corresponding to the render, which is what stops substrate variation reading through a pale finish.

Which Silo Does Your Project Belong In?

Five checks confirm whether this silo covers the scope, so the next click lands on a collection rather than another overview.

• This silo fits when you are specifying, quoting or installing an external render finish on UK masonry, carrier board or an insulated build-up, at any scale.
• Start at the substrate where the specification is still open, since the board, adhesive and key coat constrain what the topcoat can achieve above them.
• Route to render beads and mesh for corners, stop ends, bellcast drips and reinforcement, because every opening and termination on the elevation needs a profile the render silo does not carry.
• Look to the insulation silo first where thermal upgrade is the objective, since board selection and the U-value calculation come before any finish decision.
• Send the elevation and the substrate type and the specification comes back as one order — which is the point of buying from rendering materials suppliers rather than from three merchants. Bring the drawing to Renders World with the shade reference and the build-up already decided.

FAQ — Ordering, Certification and Site Conditions

What quantities does a 100 m² elevation take?

Three layers can be worked from the documents. Key coat: 100 m² × 0.3–0.5 kg/m² = 30–50 kg, which is two to four of the 15 kg CT 16 buckets. Thin-coat finish at 1.5 mm by hand: 100 m² × 2.2 kg/m² = 220 kg ÷ 25 kg = a minimum of 9 containers, since the sheet quotes that rate as a floor. Carrier boards: 100 m² ÷ 2.88 m² per 2400 × 1200 sheet = 35 sheets, and at 600 mm batten centres 35 × 27 = 945 fixings. Basecoat quantities are not published here, because no basecoat sheet was read this session.

Can Atlas and Ceresit products be mixed in one build-up?

Both manufacturers document their products as components of named, separately assessed systems — the Atlas finish under eight ITB-KOT assessments and three ETAs, the Ceresit key coat under an ETA per Ceretherm system with its own certificate and DoP numbers. Because the assessment attaches to the assembly, staying inside one manufacturer's system is what keeps that paperwork usable on a contract that asks for it.

What is the difference between a primer and a key coat?

A key coat carries fine aggregate: the CT 16 sheet describes it as a priming paint whose aggregates leave the surface rough and scratch resistant, applied at 0.3–0.5 kg/m² and dry in about three hours. A penetrating primer does a different job — CT 17 goes on absorptive substrates such as gypsum renders and chipboard first and is left about two hours before the key coat follows. They sit in different consumption bands and are not interchangeable.

What temperatures can these materials go on in?

The Atlas thin-coat finish applies between +5 °C and +30 °C, and the Ceresit CT 16 key coat between +5 °C and +25 °C, both at relative humidity below 80 %. Where the season is shorter than the programme, Atlas Eskimo extends the Atlas renders to work above 0 °C, and the render sheet asks for the surface to be protected from direct sun, wind and precipitation while it dries, which takes about 24 hours at 20 °C.

How is a finished facade maintained?

The render sheet names its own consumables: Mykos Plus for mould, decay fungi and algae, Resin Away for set material, and Salta N silicone paint as the renovation route on an aged coating. No sheet read this session states a service life in years for a thin-coat render, so maintenance is planned on inspection intervals rather than on a countdown to replacement.

What can be said about fire performance at this level?

Only what each document states about the thing it tested. The Atlas render declares A2-s1, d0 as a product under DoP 145/3/CPR, which is a product declaration and not the classification of a wall. The STS carrier board guide is a clearer case still: it answers a question about the render carrier board by quoting Class A1 for a differently named STS construction board, and gives no reaction-to-fire line in the board's own specification table. No fire class is published for the carrier board here — where a fire strategy needs one, ask STS for the classification report against the board name on the delivery note.