Description
A self-cleaning architectural concrete facade with hydrophobic UV-resistance and no separate sealer coat starts with Atlas Silkon BA — a silicone-acrylic, ready-to-use thin-coat render that finishes the Atlas concrete and wood-effect render range in a single product. A 20 kg bucket covers ~8 m² at 2.5 kg/m² with a 1.2 mm grain, complies with EN 15824:2017, and applies between +5 °C and +30 °C — making it the premium-tier choice for coastal, urban, and high-exposure UK projects where mineral renders would need more frequent maintenance.
Where Atlas Silkon BA Performs Best on UK Facades
Atlas Silkon BA is engineered specifically to imitate exposed architectural concrete — a silicone-acrylic hybrid binder system, dolomite-aggregate body, and 1.2 mm grain that delivers a monolithic, pitted, or grooved concrete read through trowel technique alone, no stamps or stencils required. Vapour diffusion resistance Sd between 0.14 m and 1.4 m places it in the breathable thin-coat range, while the silicone resin content drives the hydrophobic, self-cleaning behaviour that mineral renders cannot match.
The product earns its place on three project types: full external facades over ATLAS ETICS or ROKER EWI build-ups in wind-driven rain zones, coastal exposure, and high-pollution urban sites where the self-cleaning silicone film keeps the facade looking new for years between cleans; architectural feature panels on entrance bays, plinths, and contrast walls where the design language calls for raw-concrete aesthetics without the structural weight of precast panels; and interior wet areas including bathrooms, shower surrounds, and humid commercial spaces where the low-absorption silicone-acrylic film resists moisture ingress and biological growth that would compromise a mineral finish.
Why Trade Specifiers Choose Atlas Silkon BA
- Single-product concrete finish: Colour and weather protection in one bucket — no separate sealer coat or impregnation step, which cuts the number of trade visits per facade and removes the dependency on cure-time windows between render and sealer.
- Self-cleaning hydrophobic surface: Rain beads off and carries surface deposits with it rather than soaking in, which is why this is the specified product on coastal and urban elevations where mineral finishes need washing every two to three years.
- Silicone-acrylic hybrid binder: The acrylic fraction adds mechanical elasticity beyond pure silicone, which lets the cured film bridge thermal stress on dark grey shades that absorb significant solar heat without developing hairline cracking.
- Architect-driven texture control: Trowel technique determines the finish — light pressure for pitted, firm flat passes for monolithic, varied work for grooved or fair-faced. One product covers the design vocabulary of exposed concrete without specifying separate render types per elevation.
- Interior wet-area certified scope: Low-absorption structure makes Silkon BA usable on shower surrounds and bathroom feature walls, a use case mineral concrete-effect renders cannot reliably serve due to porosity.
- EN 15824:2017 declared performance: Documented adhesion, vapour permeability, and water absorption values mean the render slots cleanly into specified build-ups for UK regulatory submissions.
Atlas Silkon BA — Data Sheet Highlights
| Parameter | Value |
|---|---|
| Pack size | 20 kg bucket |
| Consumption | ~2.5 kg/m² |
| Coverage per bucket | ~8 m² |
| Grain size | Up to 1.2 mm |
| Thermal conductivity (λ) | 0.80 W/m·K |
| Vapour diffusion (Sd) | 0.14 m < Sd < 1.4 m (breathable) |
| Application temperature | +5 °C to +30 °C |
| Recoat / overworking window | ~2 hours at +20 °C |
| Cure time | 12–48 hours (conditions-dependent) |
| Binder chemistry | Silicone-acrylic hybrid + dolomite aggregate |
| Standard | EN 15824:2017 |
| System compatibility | ATLAS ETICS · ATLAS ROKER EWI · interior wet areas |
How to Apply Atlas Silkon BA — Priming, Trowel Technique, Cure
Silkon BA goes on over a primed substrate that has had its suction equalised and its colour brought close to the final render shade — typically with Atlas Base Coat Paint in a matching tone. On renovation jobs over existing ceramic tiles or other low-suction surfaces, the substrate needs a high-adhesion bonding primer such as Atlas Ultragrunt to create a reliable mechanical key. Mix briefly before use, even though the product is ready-to-use, to redistribute any pigment settling in the bucket.
- Apply at grain thickness: Use a stainless steel trowel to lay the render and level it back to the 1.2 mm grain. Apply only the section the team can finish within the 2-hour overworking window at +20 °C — shorter in warm conditions, longer in cool.
- Trowel for the chosen effect: Light pressure with varied direction produces pitted concrete; firm flat passes produce monolithic; ribbed roller or grooving tool produces fair-faced board-marked patterns. Decide and rehearse the technique on a sample board before scaling up.
- Maintain wet edges: Work in panel sections of 2–3 m² between stamp lines or external corners so the wet edge stays live until a natural break point. Visible lap lines on cured Silkon BA are permanent under the silicone film.
- Cure 12–48 hours: Allow the full rain-free window — 12 hours minimum in warm dry conditions, 48 hours in cool damp UK ambient before the surface tolerates rain without mark-staining.
For the full concrete-effect application method — covering primer selection, trowel technique variation, and decision points between mineral and silicone routes — read the concrete-effect render application guide. For primer selection across substrate types, the Atlas and Ceresit primer range covers everything from standard suction equalisation to tile-bonding applications.
Installation Notes — Overworking Window, Section Sizing, Site Conditions
The 2-hour overworking window at +20 °C is the timing constraint that shapes the day's work. Plan section sizes that two or three trowel-hands can lay and texture within that window — typically 6–12 m² per cycle on a uniform elevation, less around windows or detailed bays. In summer heat above +25 °C the window contracts; in cool UK spring conditions below +12 °C it extends, which gives larger sections but slower cure.
Texture is set by trowel pressure and direction, not by the product. Two installers working the same bucket produce visibly different finishes if their technique drifts — agree on the trowel motion at the sample-board stage and brief any new crew member before they touch the wall. A consistent trowel hand is what separates a fair-faced architectural finish from a patchy textured one.
Pro Tips From UK Installers Using Atlas Silkon BA
- Sample board before the elevation: Apply Silkon BA on a 600 × 400 mm primed board and rehearse the trowel technique for the agreed effect. Architectural concrete looks vary far more than colour swatches suggest — confirm in daylight, on-site, before scaling up.
- Tone the primer to the render: A grey primer under grey Silkon BA reads cleaner at any holiday or thin section than white primer would. Primer colour matters more on concrete-effect finishes than on flat-coloured renders because the texture exposes substrate at high points.
- Plan around the 2-hour window: Brief the crew on the overworking window at the day's ambient temperature. A team used to mineral renders' longer working times will overshoot the texturing window on Silkon BA if not reset on day one.
- Prime tiles before bathroom retrofits: Ultragrunt over degreased, firmly bonded tile is the path. Verify tile adhesion before specifying — any loose tiles need to come off, not be rendered over.
- Dark shades stay flat: The silicone-acrylic hybrid binder handles solar heat absorption on dark grey shades that would crack a pure-acrylic concrete-effect render — useful when the design calls for charcoal or graphite tones on south-facing elevations.
Is Atlas Silkon BA Right for Your Project?
- Right for self-cleaning concrete facades: Architectural concrete read on full elevations, contrast feature panels, or interior wet areas within ATLAS ETICS / ROKER systems in coastal, urban, and high-exposure UK locations where maintenance cycles need to be long.
- Mineral, lower-cost alternative: Atlas Cermit WN smooth render delivers a mineral concrete or wood-effect base at lower material cost per m² — better for sheltered elevations or interior dry-area work where the self-cleaning silicone premium is not justified, though it requires a separate sealer step for wood-effect colour.
- Wood-effect aesthetic instead: If the design calls for timber-board grain rather than exposed concrete, Cermit WN paired with the Bejca sealer range — teak, walnut, or birch — covers the full wood-effect palette through stamped texture and colour sealing.
- Primer-only retrofit substrate: Existing tiles, painted concrete, or sealed substrates need the right primer first — see the primer range for the correct bonding agent before specifying Silkon BA over the top.
FAQ — Atlas Silkon BA Coverage, Compatibility, Ordering
Does Atlas Silkon BA require an additional sealer coat?
The silicone-based binder and built-in hydrophobisers deliver weather protection and self-cleaning performance directly from the bucket, so no separate sealer or impregnation step is needed. That simplifies the application sequence relative to mineral concrete-effect renders, removes one cure-window from the programme, and gives a consistent low-maintenance surface from completion day onward.
Can I apply Silkon BA over existing ceramic tiles in a bathroom?
Application over firmly bonded ceramic tiles is achievable once the surface is degreased and primed with a high-adhesion bonding agent such as Atlas Ultragrunt. The grout lines should be filled to a level starting surface before the 1.2 mm render layer goes on. Verify tile adhesion across the wall before specifying — any drummy or loose tiles must come off rather than be rendered over.
What is the benefit of a silicone-acrylic hybrid over pure silicone?
The acrylic fraction adds mechanical elasticity beyond what pure silicone delivers, which lets the cured film bridge thermal expansion on dark concrete shades that absorb high solar heat without surface micro-cracking. The silicone fraction keeps the self-cleaning hydrophobic behaviour intact. This hybrid binder is the current standard for high-performance thin-coat renders working under UK weather variability.
How much Silkon BA do I need for my project?
Each 20 kg bucket covers approximately 8 m² at 2.5 kg/m² consumption. For a standard 40 m² elevation, plan for 5 buckets plus primer. Adding one spare bucket on projects above 30 m² absorbs natural variation in render thickness across texture types — pitted finishes use slightly more product than flat monolithic ones.
What temperature range can Silkon BA be applied in?
Application runs between +5 °C and +30 °C with no rain forecast for the 12–48 hour cure window after laying. Working at the warmer end shortens the 2-hour overworking interval significantly, so plan smaller sections in UK summer afternoons. Outside this range, the silicone-acrylic binder will not coalesce reliably and full hydrophobic performance is not guaranteed.
Should I specify Silkon BA or Cermit WN for a concrete-look facade?
Silkon BA is the right specification when self-cleaning performance, coastal or high-pollution exposure, dark-shade thermal resilience, or interior wet-area suitability matter — it is the premium-tier choice in the concrete-effect range. Cermit WN is the right specification for mineral breathability priority, sheltered elevations, lower per-m² material cost, or when a wood-effect grain is also wanted on the same project. Both sit within BBA-certified ATLAS ETICS systems.