Description
Grey Atlas Silicone Render is the deep-tint base of a ready-mixed, fibre-reinforced silicone finish, and it exists for the darker half of the palette. A saturated shade reaches its depth in one pass from a grey base, and the mortar in the reinforced layer beneath is chosen alongside the colour, not after it.
Grey Atlas Silicone Render 25kg on a Deep-Tint Elevation
The grey base is a thin-coat render, laid at grain thickness with a stainless steel trowel or sprayed through a plastering unit, and finished to the lambskin texture. Renders World tints it in house from the silicone render range, alongside the same render on the white base.
- Binder and reinforcement: silicone and siloxane resins with dolomite aggregate and quartz flours, reinforced with cellulose fibres.
- Texture and grain: lambskin, at a maximum of 1.5 mm on the N-15 grain or 2.0 mm on N-20.
- Colour: 480 shades from the SAH plasters and paints range, plus any individual colour matched to a reference.
Two conditions attach to a deep grey and both belong on the specification, not in the yard. Atlas ties intensive colours to the light reflectance of the finished shade, expressed as HBW, and sets two declared thresholds: colours above HBW 15% and, on a different reinforcing mortar, colours down to HBW 6%. Which threshold applies is decided by the mortar the reinforced layer is built from, so take the HBW figure from the SAH colour charts and sample books and settle the basecoat and the shade together. The wider background is in the guide to dark render colours and solar exposure.
The Exposures This Render Is Named For
Most technical documentation is written in generalities. This one names its conditions, and the list reads like a survey of the elevations that ask the most of a finish.
- Impact at ground level — playground surrounds, walk-through and drive-through gateways and vehicle parking areas. Resistance to mechanical damage is one of the two exposures the manufacturer puts this render forward for.
- Soiling — operational dust and industrial pollution: urban and built-up areas, industrial, investment and economic zones.
- Damp and shade — wetlands and ground near water, close proximity to woodland and green areas, shaded elevations, and rural and farm sites.
Three declared mechanisms answer that list and they do different jobs. Hydrophobicity through the body and at the surface comes from the high silicone and siloxane resin content: dust and dirt have nothing to bind to, and rainfall carries them off instead of driving them in. Very low surface absorption comes from a tight pile of textured aggregate and fine fillers, which is what limits the structural absorption a facade stains through. And a photocatalytic effect adds active self-cleaning at the surface together with increased protection against micro-organisms.
Resistance to algae is declared in its own right, and the reason given is specific: a high degree of hydrophobisation, an intact coating structure, and a very high content of encapsulated coating-active substances. That is the property offered to buildings near green areas and bodies of water, and at shaded elevations in city centres carrying a heavy pollution load. Fine fillers and microfibres add a fourth line, high resistance to microscratch formation, which is what keeps a saturated grey reading evenly under raking light.
Scope is stated as plainly as the exposures. An EPS ETICS elevation, a mineral wool ETICS elevation, a single-layer wall facade, a ceiling from below and an interior wall are all in scope. Eleven building types are listed and every one carries a plus, heritage buildings and passive and low-energy construction included. Six locations are listed and every one carries a plus as well.
What Is Declared for the Render Itself
The values below belong to the grey base as a product and travel with it into whichever build-up it goes. System credentials are a separate matter and sit in the table after this one.
| Property | Declared value | Scope |
|---|---|---|
| Water vapour permeability | V2 — high | Product, EN 15824:2017 |
| Water absorption | W2 — average | Product, EN 15824:2017 |
| Diffusion resistance | 0.14 ≤ Sd < 1.4 m | Product |
| Adhesion | 0.35 MPa | Product, DoP 145/3/CPR |
| Reaction to fire | A2-s1, d0 | The render alone |
| Density, ready product | approx. 1.9 g/cm³ | Product |
| Reaction, pH | 8 | Product |
| Texture and grain | lambskin; 1.5 mm N-15 or 2.0 mm N-20 | Product |
| Colour | 480 SAH shades, plus individual matching | Product |
| Working temperature | +5 °C to +30 °C | Mix, substrate and air |
| Relative humidity | below 80% | Application and setting |
| Surface dry / dry | approx. 15 min / approx. 24 h | At 20 °C and 60% RH |
| Pack size | 25 kg plastic bucket | Product |
| Shelf life | 12 months from manufacture | Product |
| Standard and DoP | EN 15824:2017 · DoP 145/3/CPR | Product |
| Intended use, outside | walls, ceilings and columns | From the DoP |
| Intended use, inside | walls, ceilings, columns, partitions | From the DoP |
| Environmental declaration | Type III, named for production | Manufacturing, not the bucket |
One line in that table is worth a sentence of its own. The English-language edition of the technical documentation prints the water absorption class as In2, which is not a designation EN 15824 uses; the Polish edition prints W2, and W2 is the class. Where a specification clause turns on that letter, ask Atlas for the current Declaration of Performance and not a translated table.
System Credentials, and Where the Fire Class Belongs
Mixing product credentials with system credentials is how a grey render ends up described as certified when it was the wall build-up that was assessed. The grey base is a component of eleven assessed systems — three of them European Technical Assessments — and of one British certificate. None of them belongs to the bucket on its own.
| Assembly | Assessment | Scope |
|---|---|---|
| ATLAS · ATLAS ROKER · ATLAS GRAWIS | ETA-06/0081 · ETA-06/0173 · ETA-16/0933 | System, European Technical Assessment |
| ATLAS ETICS · ETICS PLUS · RENOTER · RENOTER W | Four Polish national assessments | System, national assessment |
| ATLAS ROKER · ROKER G · ROKER EPS · THERMO PLUS | Four Polish national assessments | System, national assessment |
| Atlas/Aval EPS external wall insulation | BBA Agrément 13/5018, Product Sheet 1 | System, and a reaction-to-fire class |
Two reaction-to-fire classifications therefore apply and they describe different things. The grey render alone is A2-s1, d0 under its Declaration of Performance. The certified EPS construction that carries a silicone finishing coat is B-s2, d0 under BBA Agrément 13/5018, and that is the class a designer specifies to.
The certificate reaches that class for one named construction, with EPS to a maximum thickness of 250 mm and Atlas 150 alkali-resistant mesh — 150 g/m² on a 4.5 by 5.0 mm grid within that system — or the heavier Atlas 165 in the reinforced layer. Adhesive, basecoat, key coat and paint are all named in it too, so a project claiming that class is built to the certificate's own component list and not to a substitution. Under it, 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.
Substrates, Seasoning and the Layer Beneath
Seasoning times are specific, not general and they assume bonding conditions of +20 °C and 50% humidity. One row of this table saves a whole coat, and it is the row most specifications miss.
| Substrate | Seasoning before rendering | Priming |
|---|---|---|
| Reinforced layer built with Atlas Stopter K-50 | min. 3 days | No key coat required |
| Reinforced layer built with other Atlas mortars | min. 3 days | Key coat, chosen to suit the mortar |
| New cement and cement-lime plaster | min. 7 days per 1 cm of thickness, moisture 4% | Key coat |
| Concrete | min. 28 days, structural moisture below 4% | Key coat |
| Gypsum substrates, internal | moisture below 2% | Atlas Uni-Grunt first, then a key coat |
| Plasterboard and fibre-cement board, firmly fixed | moisture below 2% | Key coat |
| Sound paint coatings, internal only | no seasoning requirement | Key coat |
Stopter K-50 is one of three mortars exempted from a key coat under this render, and it is the one Renders World carries. On a reinforced layer built with it, the render goes straight on after seasoning, which removes a material, a delivery and a working day from the programme. Everywhere else a key coat goes on first, and the choice follows the mortar, not the render — that layer sits in the exterior render primers range.
Whatever the substrate, it wants to be stable, seasoned, dry, even and clean. Unevenness is filled with a levelling or plastering mortar and primed before the repair. Where there is biological growth on the wall under a planned grey — and on the damp, shaded and tree-lined elevations this render is made for that is the rule and not the exception — it is removed with Atlas Mykos Plus biocidal wash before anything else happens.
Applying the Render: Laying, Texturing and Spraying
By hand
- Stir, never modify. The paste arrives ready to use and must not be diluted, thickened or combined with other materials. Stir it immediately before use to even out the consistency.
- Lay at aggregate thickness with a smooth stainless steel trowel, drawing the surplus back into the bucket and stirring it in before it returns to the wall.
- Texture with a plastic float in circular motions to pull the lambskin grain even.
By machine
A sprayed grey runs on the 1.5 mm N-15 grain only, so a spray programme fixes the grain before anything else is decided. A Wagner PC 830 takes a 6 mm nozzle at minimum feed and 2.2 bar. A Graco TexSpray RTX 5500 PX takes a 6 mm round, 8 mm round or 6 mm flat nozzle at medium feed. A Graco TexSpray Fast Finish takes a 6 mm flat, 6 mm round or 8 mm flat nozzle at average feed with the pressure in the green zone. Quoted pressures assume standard hose lengths and are set on site once the hoses run longer, and pushing a little key coat down the hose first wets it and keeps it clear.
Machine-applied render is left untextured, and the two methods develop the surface differently enough that the difference can show as a slight change of colour. Combining them on one building is ruled out for that reason, so fix the method before the first elevation. Panel planning, wet edge and trowel discipline are set out in full in the step-by-step thin-coat rendering method.
Coverage and How Many Buckets to Order
Two figures are published for each grain: a minimum and an average. Order Grey Atlas Silicone Render against the average and the delivery covers the wall.
| Grain and method | From | Average | Per 25 kg bucket, at the average |
|---|---|---|---|
| 1.5 mm N-15, by hand | 2.2 kg/m² | below 2.5 kg/m² | about 10 m² |
| 1.5 mm N-15, by machine | 1.9 kg/m² | below 2.5 kg/m² | about 10 m², and usually better |
| 2.0 mm N-20, by hand | 2.8 kg/m² | below 3.0 kg/m² | about 8.3 m² |
A 100 m² grey elevation at 1.5 mm therefore comes to ten buckets, or eleven once 10% is added for reveals, corners and detailing; at 2.0 mm the same wall needs about twelve. Machine consumption runs below the hand figure because a sprayed coat carries its aggregate less densely, and all of these figures assume even substrates under the ITB 2020 technical conditions, so the reliable number still comes from a trial patch on the wall in front of you. Within that certified build-up the BBA gives a coverage of 2.5 to 3.5 kg/m² across the grain sizes, which brackets both published figures. For a whole-project take-off across primer, basecoat and finish, the render coverage calculator runs the arithmetic layer by layer.
Conditions, Batching and Cold-Weather Work
- Working window: +5 °C to +30 °C with relative humidity below 80%, for mix, substrate and air, right through setting. Protect the surface from direct sun, wind and rain during the work and while it dries.
- Shoulder season: work above 0 °C at humidity to around 80% is permitted after adding Atlas Eskimo setting accelerator, which is the documented cold-weather route and not a workaround.
- Drying: approximately 15 minutes to surface dry and 24 hours through, at 20 °C and 60% RH. Near +5 °C in high humidity the setting time lengthens, which means a longer protected period and a slower programme.
Two habits keep a saturated grey reading as one wall. Keep a single manufacture date across one surface, which is what holds a grey continuous from the first panel to the last. And establish by trial, for this substrate and this week's weather, the largest area you can pull and float in one cycle. Then plan the breaks at corners, building returns, downpipes and colour changes instead of mid-panel, and work wet on wet within each panel, so every join lands where it was meant to.
Grey Atlas Silicone Render is excluded from horizontal surfaces in permanent contact with water or snow, and from surfaces wetted by rising damp — both settled at design stage with a drip detail and a plinth finish. Wash tools in clean water straight after use, and Atlas Resin Away, sold here as Szop 2000, lifts hardened residue. When an ageing grey facade eventually needs refreshing instead of re-rendering, a silicone masonry paint is the documented renovation route, and those sit in the silicone masonry paint range.
Grey Base or White Base — What Decides It
Grey Atlas Silicone Render and the white base are the same render under one Declaration of Performance, and the published documentation names no tinting base anywhere. The split between them is our own tinting practice, and it is about which base reaches your shade in the fewest passes.
| Tinting base | Chosen for | What the documentation states |
|---|---|---|
| Grey base — this bucket | Mid-tone, deep and saturated SAH shades | No separate declaration for a base |
| White base | Whites, creams and the lightest tints | No separate declaration for a base |
So the honest statement is a short one: which base you take is a colour decision made in our mixing room, and no document sets one base above the other on performance. Take the shade from the fan deck before anything is tinted, and expect a bespoke reference to be confirmed against a tinted sample.
Ordering, Tinting and Collection From Southampton
Renders World tints Atlas and Ceresit in house, to order, on a separate mixer for each manufacturer, so a grey is mixed for the job, not picked from whatever is already on a shelf.
- Dispatch: same day when the stock is there.
- Delivery: quoted by our team after the order, not calculated at checkout, because render travels as parcels or pallets depending on the quantity. A 25 kg bucket goes as a parcel and next-business-day carriage is one of the options quoted. Every delivery is kerbside.
- Collection: in person at Unit 9A, Central Trading Estate, SO14 5JP Southampton, Monday to Friday 7am to 5pm and Saturday 7am to 12pm. The render is tinted at the counter and goes with you the same visit; the phone number is on our contact page.
Larger orders inside 15 miles of Southampton go out free in our own van, and beyond that a per-mile rate runs out to sixty miles. Tinted material is mixed for your order and sits outside the 14-day change-of-mind return, which is set out in the cancellations and returns terms.
FAQ — Deep Shades, Fire Class and Maintenance
- Four questions decide a grey-base specification: how dark the elevation may go, which fire class belongs on the drawing, how many buckets to order, and how the facade is refreshed years later.
How dark can the elevation go?
As dark as the SAH palette runs, with one condition attached. Specify Grey Atlas Silicone Render where the finished shade is mid-tone or deeper. Intensive greys are tied to the light reflectance of the finished shade, and two thresholds are published, HBW above 15% and HBW above 6%, each tied to the mortar the reinforced layer is built from. HBW is a reflectance figure, so the lower the number the deeper the shade. Take the figure from the colour reference, not by eye, and settle the reinforcing mortar and the shade in the same conversation.
What reaction-to-fire class can I quote on a specification?
Both, with their scopes named. The render alone is A2-s1, d0 under DoP 145/3/CPR to EN 15824:2017. The certified EPS construction carrying a silicone finishing coat is B-s2, d0 under BBA Agrément 13/5018, with height restrictions of 18 m in England, Wales and Northern Ireland and 11 m in Scotland. Write the specification to the system class, built to the certificate's own component list, then check it against the national Building Regulations for the building in question.
How many 25 kg buckets do I need for 100 m² at 1.5 mm?
Plan on the average figure of below 2.5 kg/m², which gives about 10 m² per bucket. That makes ten buckets for 100 m², or eleven with a 10% allowance for waste, corners and an uneven basecoat. At 2.0 mm the average rises to below 3.0 kg/m², so the same wall needs roughly twelve.
How is the finish maintained, and can it be overpainted later?
Routine maintenance on a grey elevation is light: the hydrophobic, self-cleaning surface is built to shed dust and dirt during rainfall. When an ageing facade eventually needs refreshing, Atlas names painting with a silicone masonry paint as the renovation route, which keeps the vapour-open character of the whole build-up and is a repaint and not a re-render.
Technical Documentation