Description
Tinted in 480 Atlas SAH shades on a dedicated machine at our Southampton warehouse, Atlas Silicone-Silicate Render pairs an organic siloxane resin with an inorganic silicate binder for V1 vapour permeability at Sd below 0.14 m, the highest breathability class in the range, covering approximately 10 m² per 25 kg tub and certified to EN 15824 under DoP 125/CPR across three Atlas ETICS approvals.
Where Atlas Silicone-Silicate Render Performs Best — Heritage and Breathable UK Walls
Atlas Silicone-Silicate Render is a hybrid dual-binder thin-coat finish built for listed buildings, conservation-area properties, pre-1919 solid walls, AAC blockwork, and any substrate that depends on outward evaporation to manage moisture, certified V1 with Sd below 0.14 m to EN 15824 (DoP 125/CPR), with A2-s1,d0 reaction to fire and ≥ 0.35 MPa adhesion. Part of the premium silicone render range, this 25 kg ready-mixed render covers approximately 10 m² at 1.5 mm grain (2.5 kg/m²) or 7.8 m² at 2.0 mm grain (3.2 kg/m²), with a spotted texture available across the full SAH palette plus bespoke RAL or NCS matching.
The chemistry sets this render apart from every other thin-coat in the Renders World range. An organic siloxane resin delivers hydrophobic surface behaviour and crack-resistant flexibility, while an inorganic silicate binder forms a true chemical bond with mineral substrates — natural stone, lime plaster, brick, AAC blockwork — rather than relying on a polymer film alone. Dispersed microfibres reinforce the render through its full thickness, absorbing thermal expansion, settlement shifts, and minor impact so the surface flexes with the building. An acid-alkaline reaction within the binder matrix naturally suppresses algae and fungi without biocide additives that degrade over time.
Why Trade Specifiers Choose Atlas Silicone-Silicate Render
- Walls that breathe as freely as uncoated masonry: V1 vapour permeability at Sd below 0.14 m lets interior moisture escape outward almost without restriction, roughly ten times more permeable than V2-rated pure silicone, so heritage and solid-wall properties stay structurally sound and damp-free from the inside out.
- Chemical bond to mineral substrates: the inorganic silicate binder bonds chemically to natural stone, lime plaster, traditional brick, and AAC blockwork, integrating with the existing wall rather than forming a separate skin, which reduces delamination risk on irregular heritage surfaces.
- Crack-free finish on moving walls: dispersed microfibres reinforce the render throughout its full thickness, absorbing thermal expansion, settlement, and minor impact so the surface flexes with the building rather than developing hairline cracks across a long service life.
- Natural bio-protection without biocides: an acid-alkaline reaction within the binder matrix suppresses algae and fungi naturally, keeping shaded and north-facing elevations clean for the full service life of the render rather than relying on additives that degrade.
- 480 heritage and modern shades mixed on site: every tub is tinted on a dedicated Atlas machine at the Renders World Southampton warehouse, with heritage earth tones, muted limestone shades, and bespoke RAL or NCS matching mixed to order for next-day dispatch.
- Fire performance for compliance documentation: reaction to fire A2-s1,d0 under EN 13501-1, with DoP 125/CPR and three Atlas system ETA approvals, giving specifiers the documentation Building Control and warranty providers typically require, subject to each project's specific fire strategy assessment.
- Two grain sizes for texture choice: 1.5 mm (N-15) for a refined spotted texture at 2.5 kg/m², or 2.0 mm (N-20) for a deeper aggregate finish at 3.2 kg/m², matching the visual scale to the building's architectural context.
Technical Specifications — Atlas Silicone-Silicate Render Data Sheet
| Property | Value |
|---|---|
| Pack size | 25 kg plastic bucket |
| Binder type | Hybrid — organic siloxane + inorganic silicate |
| Aggregate | Marble |
| Density | Approx. 1.9 g/cm³ |
| Grain size options | 1.5 mm (N-15) · 2.0 mm (N-20) — spotted (baranek) texture |
| Coverage — 1.5 mm hand | Approx. 2.5 kg/m² — approx. 10 m² per 25 kg tub |
| Coverage — 2.0 mm hand | Approx. 3.2 kg/m² — approx. 7.8 m² per 25 kg tub |
| Vapour permeability | V1 (high) — Sd < 0.14 m to EN 15824 |
| Water absorption | W2 (medium) — ≤ 0.5 kg/m²h⁰·⁵ to EN 15824 |
| Adhesion to substrate | ≥ 0.35 MPa |
| Reaction to fire | A2-s1,d0 — EN 13501-1 (limited combustibility) |
| Application temperature | +5 °C to +25 °C (air and substrate); humidity below 80 % RH |
| Setting time | 12–48 hours depending on temperature and humidity |
| Shelf life | 12 months in sealed packaging at +1 °C to +30 °C |
| Colour range | 480 Atlas SAH shades plus bespoke RAL/NCS matching |
| Machine application | 1.5 mm grain — MAI 2 MULTIPUMP / GRACO RTX 1500 (6 mm nozzle, 1 bar) |
| Mandatory primer | Atlas Silkon ANX priming mass (consolidation primer first on high-suction substrates) |
| System approvals | ETA 06/0081 · ETA 06/0173 · AT-15-9090/2014 |
| Standard compliance | EN 15824 · DoP 125/CPR |
How to Apply Atlas Silicone-Silicate Render — Heritage Substrates, Priming, EWI Build-Up
This render works best on mineral-based substrates that need unrestricted moisture escape: cellular concrete (AAC blocks), lime-mortared heritage brick, natural stone, traditional lime plasters, and cementitious basecoats over EWI systems using polystyrene, XPS, or mineral wool boards. For high-suction substrates such as aerated block or old lime plaster, apply a consolidation primer first, then Atlas Silkon ANX priming mass — the exterior render primers range includes options matched to every common UK substrate. Embedding 150 g/m² alkali-resistant fibreglass mesh in a cured reinforced basecoat creates the stable base this hybrid finish bonds to within the ATLAS, ATLAS ROKER, and ATLAS ETICS systems.
- EWI system integration: approved within three Atlas thermal insulation systems covering EPS, XPS, and mineral wool substrates across new-build, retrofit, and over-cladding projects.
- Heritage substrates: V1 permeability and the silicate mineral bond meet the breathability and material-compatibility criteria typically referenced in BS 7913 and Historic England guidance, making this the specification conservation officers approve most readily for listed and conservation-area facades.
- Dark-colour guidance: facades with colours above a 20 % diffuse-reflection coefficient perform confidently across the full surface; for very dark shades below that threshold on insulated south-facing walls, a solar-protect formulation adds thermal management within the same system family.
- Machine application: the 1.5 mm grain is optimised for MAI 2 MULTIPUMP or GRACO RTX 1500 units with a 6 mm nozzle at 1 bar, delivering faster coverage with slightly lower material consumption than hand application.
For the heritage decision in full — BS 7913 selection criteria, planning documentation, and listed-building scenarios — the silicone-silicate render heritage and conservation guide covers the specification path, and the thin-coat render application step-by-step guide walks through the on-site method stage by stage.
Installation Notes — Mixing, Floating, Curing
The render arrives ready to use; stir with a low-speed mechanical mixer to unify consistency, then apply with a stainless-steel float at a coat thickness matching the aggregate grain. For the cleanest result, work wet-on-wet across the entire elevation rather than letting one section dry before the next, and plan technological breaks at natural boundaries such as corners, downpipes, or colour junctions so joints stay invisible on the finished facade.
- Texturing technique: texture with circular movements using a plastic float while the render is still workable; the hybrid sets slightly faster than pure silicone in warm conditions, so above 20 °C work in panels of roughly 4–5 m² and texture each immediately.
- Curing protection: protect from direct sun, wind, and rain for 12 to 48 hours depending on conditions, with scaffold sheeting on south- and west-facing elevations to control drying speed and prevent flash drying.
- Cold-weather pairing: for winter work down to 0 °C, pair with Atlas Eskimo setting accelerator to hold a manageable curing window through the colder months without compromising film formation.
- Seasonal scheduling: the seasonal application timing guide covers the full UK weather-management protocol across the calendar year.
Pro Tips From UK Installers Using Atlas Silicone-Silicate Render
Heritage and breathable-wall projects punish the assumption that a forecast temperature applies uniformly across every elevation, and the hybrid binder responds to environmental shifts noticeably faster than pure silicone. These site-tested habits keep silicone-silicate finishes uniform, conservation-compliant, and free of the artefacts that only show up after the scaffold comes down.
- Verify substrate temperature with an infrared thermometer: a forecast 8 °C does not mean the shaded north elevation is above 5 °C at 07:30, and catching that gap before the render is on the wall keeps the job on programme.
- Texture each panel immediately above 20 °C: the open time is shorter than pure silicone because the mineral binder absorbs moisture from the mix more actively, so on warm days texture each 4–5 m² panel as you go.
- Confirm the orange-lid identifier on site: the orange tub lid marks Atlas Silicone-Silicate; if you expect silicate-hybrid and the lid is not orange, check the label, because pure silicone and silicate-silicone are not interchangeable on heritage substrates.
- Calculate quantities for both grain options up front: use the render coverage calculator to build the materials list, since coverage shifts from 10 m² to 7.8 m² per tub between 1.5 mm and 2.0 mm grain.
- Confirm grain size with the conservation officer: on listed and conservation-area projects the grain is often part of the consent documentation, so confirm against approved drawings and submit a physical swatch at the specified grain for sign-off ahead of the main delivery.
How Silicone-Silicate Compares to Other Renders in the Range
The decision between these three thin-coats comes down to substrate type and breathability need; the silicate hybrid is the heritage and solid-wall specification, while the others suit modern masonry. The table below shows where each fits.
| Variant | Key Spec | When to Choose |
|---|---|---|
| Atlas Silicone-Silicate | V1 · Sd < 0.14 m · mineral bond | Heritage, lime, AAC, solid walls |
| Ceresit CT174 1.5 mm | V1/W3 · balanced hybrid | Breathable ETICS, mid breathability |
| Ceresit CT74 | V2 · pure silicone · lower cost | Standard modern masonry facades |
Is Atlas Silicone-Silicate Render Right for Your Project?
- Yes — for heritage, lime-mortared, or AAC-block walls: this is the right choice when the wall is solid masonry with lime mortar, cellular concrete, natural stone, or any heritage substrate where V1 breathability is required by conservation officers, surveyors, or the building's own moisture needs — the one thin-coat in the range that lets moisture escape almost as freely as an uncoated surface while delivering hydrophobic rain protection, microfibre crack resistance, and A2-s1,d0 fire performance in a single through-coloured coat.
- Standard new-build or modern masonry? The broader premium silicone render collection includes pure silicone finishes that deliver the same self-cleaning performance at a lower cost point, since the additional silicate binder is unnecessary on substrates that do not rely on outward evaporation.
- Below the DPC or in a splash zone? For plinth heights, ground-level impact zones, and any area below the damp-proof course, the mosaic render range provides the heavy-duty impact resistance those conditions demand, pairing on upper elevations with silicone-silicate for a two-tone heritage-appropriate facade.
FAQ — Atlas Silicone-Silicate Render Coverage, Heritage Use, Specification
How much silicone-silicate render do I need for my project?
A single 25 kg tub covers approximately 10 m² at 1.5 mm grain (2.5 kg/m²) or roughly 7.8 m² at 2.0 mm grain (3.2 kg/m²). For a typical 80 m² heritage cottage facade at 1.5 mm, budget eight tubs plus one extra for waste and detailing around reveals, corners, and pipe cut-outs. Machine application slightly reduces consumption, but always round up to the next full tub so you can maintain the wet-on-wet technique without running short mid-elevation.
Is this render suitable for listed buildings and conservation areas?
V1 vapour permeability at Sd below 0.14 m makes this the most breathable thin-coat render in the range, and the silicate binder bonds chemically to mineral substrates like lime plaster and natural stone rather than sitting as a polymer film, which is why conservation officers typically approve it more readily than polymer-only finishes for listed and conservation-area properties where BS 7913 and Historic England guidance recommend materials compatible with traditional fabric. Each project's planning and listed-building consent process determines the final acceptable specification, so confirm with the local conservation officer ahead of ordering.
What makes this render different from pure silicone render?
The practical difference is breathability and substrate bonding. Pure silicone renders typically achieve V2 permeability (Sd 0.14–1.4 m), which works well for modern masonry but restricts moisture movement on solid lime-mortared walls that rely on outward evaporation. This hybrid achieves V1 (Sd below 0.14 m), roughly ten times more permeable, and its inorganic silicate component bonds chemically with mineral substrates. For standard new-build, pure silicone is the correct and more cost-effective choice; for heritage, AAC, and high-permeability substrates, the silicone-silicate hybrid satisfies both the building's moisture needs and the conservation officer's requirements.
Does Atlas Silicone-Silicate Render meet fire safety requirements?
The render carries an A2-s1,d0 (limited combustibility) reaction to fire classification under EN 13501-1, which typically satisfies the fire performance requirements for residential and commercial facades subject to each project's specific fire strategy assessment. Three Atlas ETICS system approvals document performance across complete build-ups including EPS, XPS, and mineral wool substrates, and pairing the render with mineral wool insulation delivers the highest-rated compliant specification where stricter classification is required.
What colours are available, and can you match a heritage shade?
The full 480-shade Atlas SAH palette is tinted on a dedicated machine at the Southampton warehouse for next-day dispatch, including heritage earth tones, muted limestone shades, and soft pastels that complement traditional masonry. For a shade outside the standard range, the team mixes bespoke colours to order, matching specific RAL codes, NCS references, or another manufacturer's swatch. Grain size affects how a colour reads: a 2.0 mm texture casts deeper micro-shadows that can make the same pigment appear marginally darker than 1.5 mm, so confirm the shade on a physical swatch at the grain you plan to specify. Browse the colour sample catalogues to view the palette on rendered swatches.
Is Atlas Silicone-Silicate Render an environmentally responsible choice?
The formulation is water-based with maximally reduced VOC content and uses only natural marble fillers. The thin 2.5 kg/m² rate at 1.5 mm grain generates substantially less material waste per square metre than a traditional sand-and-cement render at 15–20 mm, and the long through-coloured service life removes the recurring resource cycle of periodic repainting, so the total environmental footprint over the building's life is significantly lower than thicker, shorter-lived alternatives — an important consideration on heritage projects where sustainability and material compatibility are both priorities.
Technical Documentation — Atlas Silicone-Silicate Render TDS and DoP