Description
Grey-based thin-coat finishes reach saturated colour without repeat coats, and this one is cleared for shades with a light reflectance above HBW 6% over a Stopter K-100 reinforced layer. Order against 2.5 kg/m² at 1.5 mm grain, or roughly 10 m² per 25 kg bucket, rather than the 2.2 kg/m² minimum.
Where the Grey Base Fits on UK Facades
Grey Atlas Silicone Render is the pigment base for mid-tone and dark facade shades, declared to EN 15824:2017 under DoP 145/3/CPR, and used as the finish coat of ETICS build-ups over EPS and mineral wool. It is the deep-tint route inside the Renders World silicone render range, listed at £59.50 per 25 kg bucket (August 2026).
The same data sheet clears the render for even mineral substrates and for internal walls, ceilings and columns, so one specification can carry the elevation, the reveals and a soffit return. What changes between those situations is the substrate itself, and the sheet sets a seasoning figure for each.
- Reinforced layer of an ETICS build-up — minimum 3 days at +20 °C before the finish coat goes on.
- Concrete — minimum 28 days, structural moisture below 4%.
- New cement and cement-lime plaster — minimum 7 days per 1 cm of thickness, moisture 4%.
- Gypsum substrates and boards, internal only — moisture below 2%, primed with Atlas Uni-Grunt first.
Why Specifiers Choose the Grey Base
- Deep shades are inside the declared range: the sheet permits colours above HBW 15% over an Atlas Hoter U2, Hoter U2-B or Hoter U2 White reinforced layer, and down to HBW 6% where that layer is Atlas Stopter K-100 — so the mortar under the render decides how dark you can go.
- 480 SAH shades plus bespoke matching: the Atlas colouring system covers 480 colours from the SAH plasters and paints range, with individual colours mixed to a customer reference.
- Self-cleaning hydrophobic surface: a high silicone and siloxane resin content keeps dust and dirt from bonding, and the sheet also claims a photocatalytic self-cleaning effect on the facade.
- Flexible and fibre-reinforced: cellulose fibres and dedicated polymer resins bridge thermal stress, and with Atlas Stopter K-100 adhesive the render forms a system rated at 140 J impact and 30 m/s hail resistance — a system figure, not a bucket figure.
- V2 vapour permeability: a diffusion resistance of 0.14 ≤ Sd < 1.4 m keeps the finish coat open, which matters on a retrofitted solid wall where moisture needs an outward path.
- Colour fastness tested on Xenotests: hybrid inorganic and organic pigments with reflective additives, which is why a saturated grey holds its tone rather than chalking back.
- Cold-weather route on file: the standard window is +5 °C to +30 °C, and the sheet permits use at reduced temperatures above 0 °C after the addition of Atlas Eskimo.
Technical Specifications and the Scope Behind Each Figure
Every figure below comes from a document fetched for this page, and the scope column matters as much as the value — three of these belong to a system rather than to the bucket.
| Property | Declared value | Scope |
|---|---|---|
| Pack | 25 kg plastic bucket | Product |
| Density | approx. 1.9 g/cm³ | Product |
| Texture and grain | Lambskin; max 1.5 mm (N-15) or 2.0 mm (N-20) | Product |
| Colour | 480 SAH shades, plus individual colour to order | Product |
| Water vapour permeability | V2 — high | DoP 145/3/CPR, EN 15824:2017 |
| Diffusion resistance | 0.14 ≤ Sd < 1.4 m | Product |
| Adhesion | 0.35 MPa | DoP 145/3/CPR |
| Water absorption | Average — printed In2 on the English sheet, W2 on the Polish sheet | DoP 145/3/CPR; designation differs by sheet |
| Reaction to fire, product | A2-s1, d0 | The render alone, under the DoP |
| Reaction to fire, system | B-s2, d0 | Atlas/Aval EPS system, BBA 13/5018 |
| pH | 8 | Product |
| Application temperature | +5 °C to +30 °C; above 0 °C with Atlas Eskimo | Product |
| Relative humidity | < 80% | During application and setting |
| Drying | approx. 15 min surface, approx. 24 h through | At 20 °C, 60% RH |
| Shelf life | 12 months from date of manufacture | Product |
| System assessments | ETA-06/0081, ETA-06/0173, ETA-16/0933 | ATLAS, ATLAS ROKER and ATLAS GRAWIS systems, of which the render is a component |
Read the last row as written: those European Technical Assessments belong to three insulation systems that contain this render, not to the bucket on its own. The one figure worth carrying into a purchase order is the water absorption line, where two editions of the manufacturer's own sheet print different designations for the same middle class — ask Atlas for the current DoP letter if a specification clause depends on it.
Reaction to Fire: Product Class and System Class
Two classifications apply and they describe different things, so specify on the assembly rather than the bucket. The product class is A2-s1, d0, declared for Atlas Silicone Render under DoP 145/3/CPR to EN 15824:2017. The certified system class is the stricter B-s2, d0, and that is the number a designer should work to.
BBA Agrément Certificate 13/5018, Product Sheet 1, fourth issue 25 October 2022, awards B-s2, d0 to one specific construction, and the render is named in it:
- Adhesives — Atlas Stopter K-20, Atlas Hoter S (Aval KT 53) or Atlas Hoter U (Aval KT 55).
- Insulation — EPS of different types, 250 mm maximum thickness; the insulation in isolation is classified E.
- Basecoats — Atlas Stopter K-20 or Atlas Hoter U (Aval KT 55), with Atlas 150 or Atlas 165 mesh.
- Key coats — Atlas Cerplast (Aval KT 16) or Atlas Silkon ANX.
- Finishing coats — Atlas Cermit Mineral or silicone render; paints Atlas Salta E, Salta N or Salta.
Under that certificate the system is not for buildings with a storey more than 18 m above ground level in England, Wales and Northern Ireland, and not for buildings with a storey 11 m or more above ground level, or 1 m or less from a boundary, in Scotland. Within those limits a B-s2, d0 construction may sit at any proximity to a boundary in England, Wales and Northern Ireland, and the certificate asks the designer to confirm the classification against the national Building Regulations for the specific project — which is the right order of work on any facade above two storeys.
How to Apply the Render: Key Coat, Mixing and Wet Edge
The bucket arrives ready to use and must not be diluted, thickened or combined with other materials; stir it to even out consistency immediately before use. Under the certified system the key coat for a silicone finish is Atlas Silkon ANX, applied at 0.25 to 0.35 kg/m², over a basecoat carrying Atlas 150 alkali-resistant mesh.
The data sheet also permits Atlas Cerplast on certain substrates, so the two are not interchangeable by default — the certificate ties Cerplast to the mineral, acrylic and acrylic-silicone finishes and Silkon ANX to this one. Where the job is not a certified build-up, the preparation route runs through the exterior render primers range and the substrate seasoning figures above.
Laying and Texturing
- Lay at aggregate thickness with a smooth stainless steel trowel, drawing excess back into the bucket and stirring it in.
- Texture with a plastic float in circular motions for the lambskin effect; machine-applied render is not textured.
- Work wet-on-wet and never let a laid batch skin before the next is pulled to it, or the join stays visible.
- Plan technological breaks at corners, building folds, under downpipes and at colour changes, decided before the first bucket opens.
- Machine application is N-15 only — Wagner PC 830, 6 mm nozzle, minimum feed 2/10 at 2.2 bar, or Graco TexSpray RTX 5500 PX, 6 mm round nozzle at medium feed. Prime the hose with a little Atlas Silkon ANX first.
One consequence of that last point is worth planning around: the 2.0 mm N-20 grain is hand-applied only, so a spray programme commits you to 1.5 mm. Combining hand and machine application on the same building is not permissible, because the two textures differ enough to read as a colour difference. The step-by-step thin-coat application method covers the full sequence from basecoat to final float.
Coverage and How Many Buckets to Order
Two editions of the manufacturer's sheet quote consumption differently, and the safer number is the higher one. The English sheet gives from 2.2 kg/m² hand-applied at 1.5 mm; the Polish sheet gives an average below 2.5 kg/m² for N-15. Order grey Atlas Silicone Render against 2.5 kg/m² and the delivery covers the wall.
- 1.5 mm hand, per bucket: 25 kg ÷ 2.5 kg/m² = 10 m². The 2.2 kg/m² minimum would give 11.4 m², which assumes a perfectly even substrate.
- 1.5 mm machine: from 1.9 kg/m², so consumption falls, but only on the N-15 grain.
- 2.0 mm hand: from 2.8 kg/m² on the English sheet, average below 3.0 kg/m² on the Polish sheet — plan on 3.0 kg/m², about 8.3 m² per bucket.
- A 100 m² elevation at 1.5 mm: 100 m² ÷ 10 m² per bucket = 10 buckets, +10% for waste and detailing = 11 buckets.
- Material cost per m²: £59.50 ÷ 10 m² = £5.95/m² at 2.5 kg/m², material only and excluding labour, primer, basecoat and mesh.
Within the certified Atlas/Aval EPS system the BBA states a coverage of 2.5 to 3.5 kg/m² for this render across its grain sizes, which brackets both sheet figures and confirms 2.5 kg/m² as a sound floor for ordering. For a whole-project take-off across primer, basecoat and finish, the render coverage calculator runs the same arithmetic layer by layer.
Conditions, Drying and Cold-Weather Work
Choose a window between +5 °C and +30 °C with relative humidity below 80%, and protect the surface from direct sun, wind and rain both during the work and while the render dries. Drying is approximately 15 minutes to surface dry and 24 hours through, measured at 20 °C and 60% RH; at around +5 °C with high humidity the setting time lengthens, which simply means a longer protected period rather than a compromised finish.
For shoulder-season programmes, Atlas Eskimo setting accelerator is the documented route to working at reduced temperatures above 0 °C and raised humidity to about 80%. The seasonal planning detail sits in the guide to render application timing across the UK year.
- Same manufacture date per elevation — the sheet asks for it explicitly to avoid shade differences.
- Not for horizontal surfaces in permanent contact with water or snow, or walls affected by rising damp.
- Clean tools in clean water immediately; Atlas Resin Away lifts cured residue.
- Treat biological growth first — the sheet names Atlas Mykos Plus or Mykos Nr 1 for substrate infestation before priming.
Installer Tips for Deep Tints
A saturated grey is less forgiving of pace than a white, and the trade habits that keep it even are worth setting out before the scaffold goes up.
- Confirm the reinforced-layer mortar before ordering the shade. HBW above 15% needs Hoter U2, Hoter U2-B or Hoter U2 White beneath; anything down to HBW 6% needs Stopter K-100. Choose the mortar and the shade together and the order is right first time.
- Take the HBW figure from the colour reference, not the eye. The SAH colour charts and sample books carry the reference a supplier can check the threshold against.
- Size the elevation to one wet-edge cycle. The sheet asks you to establish experimentally, for the substrate and the day's weather, the maximum area you can pull and float in one cycle — do that on the least visible elevation first.
- Brief the client on solar exposure for the deepest shades. The background is covered in the guide to dark render colours and solar exposure, and specifying within the HBW thresholds keeps the finish inside the manufacturer's declared range.
- Keep one spare bucket from the same batch for reveal returns and making good after scaffold strike.
Grey Base or White Base: How to Choose
Both buckets are Atlas Silicone Render, and the fetched sheet declares one set of performance figures without differentiating by base colour. The decision is therefore about the shade you are tinting to, not about performance.
| Variant | Declared position on the sheet | Choose it when |
|---|---|---|
| Grey base — this bucket | V2 · 0.35 MPa · A2-s1, d0 · 480 SAH shades | Mid-tone, dark and saturated tints, and contemporary greys |
| Atlas Silicone Render on the white base | Same declared figures — the sheet quotes no separate values by base | Pure whites and the lightest tints, where a grey base would dull the shade |
Is the Grey Base Right for Your Project?
- Specify grey Atlas Silicone Render where the finished shade is mid-tone or darker, the reinforced layer is Hoter U2 or Stopter K-100, and the build-up sits within the certificate's height limits.
- For the lightest shades, the white base is the same product with a different starting pigment.
- For an aged facade that needs refreshing rather than re-rendering, the sheet names Atlas Salta N as the renovation route — that sits in the silicone masonry paint range.
- For the plinth below this finish, a harder decorative coat from the mosaic render range for plinths handles the splash zone.
- Still weighing binder types and brands? The silicone render buying criteria guide ranks the range on certificate scope, grain and coverage.
When the shade and the reinforced layer are settled, order the 25 kg bucket from Renders World at £59.50 and confirm the tint reference with the order.
FAQ: Coverage, Compatibility, Fire and Ordering
How many 25 kg buckets do I need for 100 m² at 1.5 mm?
Plan on 2.5 kg/m², the higher of the two consumption figures the manufacturer publishes, which gives 10 m² per bucket. That makes 10 buckets for 100 m², or 11 with a 10% allowance for waste, corners and an uneven basecoat. At 2.0 mm the figure rises to about 3.0 kg/m², so the same wall needs roughly 12 buckets.
What reaction-to-fire class can I quote on a specification?
Quote both with their scopes. The render alone is A2-s1, d0 under DoP 145/3/CPR; the Atlas/Aval EPS system containing it is B-s2, d0 under BBA Certificate 13/5018, with height restrictions of 18 m in England, Wales and Northern Ireland and 11 m in Scotland. Specifications should be written to the system class, then checked against the national Building Regulations for the building in question.
Which key coat goes under this render?
Atlas Silkon ANX, at 0.25 to 0.35 kg/m², is the key coat the BBA certificate ties to silicone render within the certified system. The data sheet permits Atlas Cerplast on some substrates, so confirm which applies to your build-up before ordering, and use Silkon ANX where the certified system is being claimed.
How dark a shade can I go?
Above HBW 15% with an Atlas Hoter U2, Hoter U2-B or Hoter U2 White reinforced layer, and above HBW 6% where that layer is Atlas Stopter K-100. HBW is the light reflectance coefficient, so the lower the number the deeper the shade — choosing the mortar first opens up the darker half of the palette.
Can it be sprayed?
Yes, on the 1.5 mm N-15 grain only, using a Wagner PC 830 with a 6 mm nozzle at minimum feed and 2.2 bar, or a Graco TexSpray RTX 5500 PX with a 6 mm round nozzle at medium feed. Machine-applied render is not floated afterwards, and hand and machine application must not be combined on one building because the textures read differently.
How is the finish maintained, and can it be overpainted later?
The hydrophobic, self-cleaning surface is designed to shed dust and dirt during rainfall, so routine maintenance is light. When an ageing facade eventually needs refreshing, the sheet names painting with Atlas Salta N silicone paint as the renovation route, which keeps the vapour-open character of the build-up.
Is there any environmental documentation?
Atlas states that production of this render is covered by a Type III environmental declaration, referenced on the technical data sheet. Ask for the declaration itself if a project needs the figures behind it for a sustainability submission, as the data sheet names the declaration rather than reproducing its content.
Technical Documentation