Knowing how to choose silicone render starts earlier than most shortlists do. Finishes that sit beside each other on the same shelf, at almost the same cost per square metre, still belong on different walls — and what separates them is the line each manufacturer prints in its own declaration, not the line in the brochure.
How to Choose Silicone Render in the UK: Start with the Declaration
Four properties every finish must declare under EN 15824 decide most specifications, and one habit keeps them usable: hold the product's own declaration apart from the certificate of the system it sits in. The two answer different questions, so a safe specification quotes each in its own scope.
- Declared vapour permeability class. Class V1 is the more open of the two classes in play here, and on a solid wall that dries outwards it is the property the build-up turns on. Every finish in the Renders World silicone render range prints its class on the sheet.
- Consumption, per grain size. Consumption turns a bucket into a project quantity, and it moves with grain: the Atlas sheet goes from 2.2 kg/m² at 1.5 mm to 2.8 kg/m² at 2.0 mm, the Ceresit sheets from 2.1–2.5 kg/m² to 3.1–3.4 kg/m² across the same step.
- Whose document carries the number. A class belongs to whatever was tested. Some figures are declared for the product, others only for a named system assembly, and keeping them apart is what makes a specification hold.
- Colour depth, which is really a basecoat question. Deep shades are governed by a light reflectance threshold tied to the reinforced layer underneath, so the colour decision is settled in the mortar choice.
Match the Render to the Wall: Four UK Project Types
Most shortlists go wrong where a headline feature replaces the exposure profile of the actual building. Working from the wall backwards keeps a specification honest and usually cheaper.
- New-build or retrofit EWI on sound masonry. A mainstream 1.5 mm silicone finish carries the centre of the UK market, and the decision reduces to colour depth and certificate scope.
- Solid-wall and conservation work. Outward drying dominates, so the declared permeability class and the key coat named beside it matter more than surface technology.
- Coastal and estuary elevations put salt loading and driving rain first, which moves the weighting to hydrophobicity and detailing; the coastal render selection guide for salt-spray elevations works through that zone.
- Plinths and splash zones below the render line. Ground-level impact is a different job, and a finish from the mosaic render range for plinths takes it while the silicone finish runs above.
What the Sheets Declare, Side by Side
Each entry states what the manufacturer's own document prints, and stops where that document stops. Where a figure exists only at system level, it is named as a system figure.
Atlas Silicone Render — the widest documented reach
The white 25 kg base of the Atlas silicone finish is declared to EN 15824:2017 under DoP 145/3/CPR, with V2 permeability at 0.14 ≤ Sd < 1.4 m, adhesion of 0.35 MPa and A2-s1,d0 reaction to fire stated at product level. Its water absorption is a lesson in document discipline: the Polish sheet prints W2, the English one prints "In2", which is not a class EN 15824 defines. The grey base for deeper tints shares the sheet and its palette of 480 SAH shades. Inside BBA Agrément Certificate 13/5018 it is a named finishing coat of the Atlas/Aval EPS system, and the certified coverage in that role is 2.5 to 3.5 kg/m² — above the 2.2 kg/m² the sheet itself allows by hand, so ordering to the certified band satisfies both documents. A brand-level comparison of the two ranges sits in the Atlas and Ceresit render comparison for trade buyers.
Atlas Silicone-Silicate — V1 with a full product declaration
The Atlas silicone-silicate render at 25 kg declares EN 15824:2017 under DoP 125/3/CPR with class V1 at Sd below 0.14 m, W2 water absorption, adhesion of 0.35 MPa and A2-s1,d0 at product level, across 406 SAH shades. Consumption starts at 2.2 kg/m² by hand and 1.9 kg/m² by machine at 1.5 mm. Inside BBA 13/5018 its certified coverage as the system's silicone-silicate finish is 2.5 to 3.0 kg/m², with Atlas Silkon ANX named there as its key coat.
Ceresit CT 74 — V1 with the highest declared adhesion
Ceresit CT 74 in white at 1.5 mm grain declares V1 with an Sd of 0.14 m, W3 water absorption and adhesion of 0.6 MPa, with consumption of 2.1 to 2.5 kg/m² at that grain and a twelve-month shelf life. Its sheet is candid about chemistry, printing a base of water-dispersed silicone and acrylic resins with mineral fillers — useful before anyone frames silicone and acrylic as a clean split. Its fire classes are printed per Ceretherm system, and BBA 14/5142 appears as a document of reference.
Ceresit CT 76 Solar Protect — UV absorbers and an 18-month shelf life
CT 76 Solar Protect at 25 kg is a silico-elastomeric render whose stated mechanism is an increased quantity of UV absorbers with a self-healing surface effect. Its sheet claims no infrared or heat reflection; it asks for a light reflectance value of HBW 15 or above. It declares V1, W3 and 0.6 MPa like CT 74, with an 18-month shelf life against CT 74's twelve. The same sheet states it should not be applied on highly sunny walls, so its case is light-fastness of colour, not a cooler wall.
Atlas Gemini RS — Polish assessment scope, no fire line
Atlas Gemini RS in white 25 kg declares EN 15824:2017 under DoP 280/CPR with V2 permeability at 0.14 ≤ Sd < 1.4 m, W2 water absorption, adhesion of 0.35 MPa and consumption from 2.3 kg/m² by hand, across 406 SAH shades at a single grain of up to 1.5 mm. Its sheet prints no reaction-to-fire line at all, and its system approvals are Polish national assessments. BBA 13/5018 does not name it among the system's components, so where a UK certificate is a contract condition the specification routes to the coats that certificate does name.
| Render | EN 15824 vapour class | Water absorption | Adhesion | Consumption, 1.5 mm, by hand | Reaction to fire on the sheet |
|---|---|---|---|---|---|
| Atlas Silicone Render | V2, Sd 0.14–1.4 m | W2 on the PL sheet | 0.35 MPa | from 2.2 kg/m² | A2-s1,d0 at product level |
| Atlas Silicone-Silicate | V1, Sd below 0.14 m | W2 on the sheet | 0.35 MPa | from 2.2 kg/m² | A2-s1,d0 at product level |
| Ceresit CT 74 | V1, Sd 0.14 m | W3 on the sheet | 0.6 MPa | 2.1 to 2.5 kg/m² | per named Ceretherm system |
| Ceresit CT 76 | V1, Sd not printed | W3 on the sheet | 0.6 MPa | 2.1 to 2.5 kg/m² | per named Ceretherm system |
| Atlas Gemini RS | V2, Sd 0.14–1.4 m | W2 on the sheet | 0.35 MPa | from 2.3 kg/m² | no line on the sheet |
Every cell comes from the product's own declaration, which is why the BBA coverage bands stay in the entries above: they belong to the certified assembly, not to the bucket. The cost side of the same Renders World shelf — materials against labour, layer by layer — sits in the 2026 cost-per-square-metre breakdown for silicone render.
Certificate Scope — What a BBA Number Actually Covers
No render in this group is "BBA certified" as a product, and a specification gets simpler once that is settled. BBA 13/5018 certifies the Atlas/Aval EPS system: adhesive, insulation, basecoat, mesh, key coat and finishing coat assessed together, with the assembly containing the silicone render finishing coat and the Silkon ANX key coat classified B-s2,d0. That sits alongside the A2-s1,d0 the Atlas sheets declare for the render alone, and the stricter system figure is the one a facade designer works from. Where a project needs the wider build-up, our thin coat render systems hold the primers and basecoats that go with it.
- Height and boundary conditions travel with the certificate. BBA 13/5018 restricts the system from buildings with a storey more than 18 m above ground level in England, Wales and Northern Ireland, and from a storey 11 m or more above ground level, or within 1 m of a boundary, in Scotland.
- Fire classes belong to named assemblies. The Ceresit sheets classify per Ceretherm system — A2-s1,d0 in Universal MW and B-s1,d0 in Universal EPS for CT 74 — so a class is only usable with its system name beside it.
- Durability is a system figure too. BBA 13/5018 certifies the system as remaining effective for at least 30 years when installed and maintained to its terms; no render sheet here states a service life for the finish alone.
- Classification standards are settling. Reaction-to-fire performance is now expressed to BS EN 13501, the older national test classes having been withdrawn, as set out in the guidance published alongside Approved Document B.
Key Takeaway: Take the vapour class, the water class, the adhesion and the consumption from the product's own declaration, and take coverage, height limits and fire class from the certificate of the named system. Three of these finishes declare V1, two declare V2, and knowing how to choose silicone render on that basis settles most UK specifications before brand ever enters it.
Ordering the Render — Quantities and Companions
Quantity is where a good specification is protected or quietly overspent. Working to the certified consumption band rather than the sheet minimum is the safer habit on a first order, because the certificate assumes the thickness the system was tested at.
- Machine and hand are not mixed. The Atlas sheet permits machine application at 1.5 mm grain only, and states that combining application methods on one building is not acceptable, because the textures differ.
- Colour depth runs into the shelf. The Atlas silicone sheet sets its deep-shade thresholds against reinforced layers of HOTER U2, HOTER U2-B and STOPTER K-100, none of which Renders World stocks; the mortar we do carry, STOPTER K-50, is the one that sheet exempts from a key coat. On the Gemini RS sheet, STOPTER K-50 is a named option for intensive colours, which makes it the route that actually exists here.
- Cold and damp windows. Both Atlas sheets allow work above 0 °C and humidity to about 80% once ATLAS ESKIMO is added, against a normal band of +5 to +30 °C; both Ceresit sheets hold a tighter +5 to +25 °C, so a shoulder-season programme is planned around the narrower pair.
Above a few hundred square metres the arithmetic changes shape, and the large-project render buying guide works through that scenario by scenario.
Written by Mariusz Saja. Technically reviewed by Rafał Wyrzykowski. Last reviewed Sep 2026.
FAQ — Choosing and Ordering Silicone Render
Which of these renders is the most vapour-open?
Three declare class V1: Atlas Silicone-Silicate at Sd below 0.14 m, Ceresit CT 74 at Sd 0.14 m, and Ceresit CT 76, whose sheet prints the class without an Sd figure. The Atlas silicone finish and Gemini RS declare V2, covering the 0.14 to 1.4 m band, which suits sound modern masonry.
Can a render be described as BBA certified?
Certification attaches to a system assembly, not to a bucket. BBA 13/5018 covers the Atlas/Aval EPS system and names the finishing coats within it; a product used outside that assembly carries only what its own declaration of performance states.
Do the Atlas and Ceresit renders share a binder?
The documents are not symmetrical. Both Ceresit sheets print a base of water-dispersed silicone and acrylic resins with mineral fillers; the Atlas sheets print no binder composition line at all, naming instead a stack of fine fillers with microfibre reinforcement against microscratching. Each manufacturer's primer, basecoat and mesh are assessed with its own finish, so a facade stays within one system.