Atlas Silicone-Silicate Render 25 kg — V1 Breathable Hybrid Finish for Heritage and High-Permeability Facades

Product Overview

Delivering V1-class vapour permeability (Sd below 0.14 m to EN 15824) in a single 25 kg tub, Atlas Silicone-Silicate Render is a hybrid thin-coat facade finish that combines an organic siloxane resin with an inorganic silicate binder to let your wall breathe as freely as uncoated masonry while shedding rainwater from the surface. This dual-binder formulation is purpose-built for substrates that demand unrestricted outward drying — cellular concrete (AAC), lime-mortared heritage masonry, pre-1919 solid walls, and high-humidity environments such as swimming-pool enclosures — where a standard silicone or acrylic render would restrict moisture movement enough to cause hidden damp. Coverage sits at approximately 10 m² per 25 kg tub at 1.5 mm grain (2.5 kg/m²), rising to roughly 7.8 m² per tub at 2.0 mm grain (3.2 kg/m²), with both options producing a dense, uniform spotted texture that retains its factory-mixed colour for over 25 years without repainting.

Your heritage or solid-wall property gets the most breathable finish in the premium silicone render collection — this silicone-silicate hybrid is the only formulation in the range rated V1. Where a pure silicone render achieves V2 permeability (Sd 0.14–1.4 m, which works well for modern masonry), this product steps up to V1 (Sd below 0.14 m), meaning moisture escapes roughly ten times more freely so your walls stay dry and sound from the inside out. The silicate component also forms a true chemical bond with mineral substrates — natural stone, lime plaster, brick — rather than relying solely on a polymer film that sits on the surface, which is why conservation officers approve it more readily than polymer-only finishes. Dispersed microfibres reinforce the entire render volume against hairline cracking from thermal stress and minor structural movement, and an acid-alkaline bio-protection mechanism suppresses algae and fungi growth without relying on biocide additives that diminish over time. Available in 400+ factory-mixed shades through the SAH Colour Scheme, the render is supplied as a through-coloured finish — select your preferred shade from the colour picker on this page or specify a SAH code from the full 400+ palette, and the pigment runs through the full applied thickness so minor surface scuffs never expose a different base colour. Manufactured to EN 15824:2009 with EC Declaration of Performance No. 125/CPR and fire classification A2-s1,d0 (limited combustibility, meaning the system adds virtually no fuel load to the facade), this render provides the documentation that Building Control, NHBC inspectors, and warranty providers require before signing off a facade system.

Key Benefits

• Unrestricted Wall Breathing (V1 Vapour Permeability): Your wall stays dry and healthy because moisture escapes outward through the render almost as freely as through uncoated masonry — classified V1 to EN 15824 with an Sd value below 0.14 m, this is the highest breathability rating available in a thin-coat system, so heritage and solid-wall properties stay structurally sound and damp-free from the inside out.
• Chemical Bond to Heritage Masonry: The inorganic silicate component within the hybrid binder bonds chemically to mineral substrates such as natural stone, lime plaster, and brick, integrating with the existing wall rather than forming a separate polymer skin — so the finish behaves structurally as part of the masonry, which reduces delamination risk on irregular, historically significant surfaces.
• Crack-Free Finish on Moving Walls: Dispersed microfibres reinforce the render throughout its entire 1.5 mm or 2.0 mm thickness, absorbing thermal expansion, settlement shifts, and minor impact stress so the surface flexes with the building rather than developing hairline cracks — giving you a seamless facade that stays intact and watertight for the full 25-year service life without the need for patch repairs.
• Self-Cleaning Bio-Protection Without Biocides: An acid-alkaline reaction within the binder matrix creates conditions that suppress algae and fungi growth naturally, keeping the facade clean on shaded and north-facing elevations without relying on biocide additives that degrade over time — so the self-cleaning effect lasts the full service life of the render, not just the first few years.
• Through-Coloured in 400+ Factory-Mixed Shades: Colour is mixed completely through the applied thickness using UV-resistant pigments and an automated dosing system, meaning minor surface scratches never expose a grey substrate and the facade never needs repainting — browse the full SAH palette through the render colour charts and sample catalogues to confirm your chosen shade on a physical swatch before ordering.
• Meets Building Control Fire Requirements (A2-s1,d0): The render adds virtually no fuel load to the facade, meeting the limited-combustibility threshold that Building Control and insurers increasingly require on multi-storey, heritage, and conservation-area properties — with a Declaration of Performance (No. 125/CPR) providing the formal documentation for sign-off.
• Proven Coverage at 10 m² per Tub: A standard 25 kg tub covers approximately 10 m² at 1.5 mm grain by hand application, so a typical 100 m² facade needs around 10 tubs plus 10 % waste allowance — making quantity planning straightforward and minimising material cost uncertainty before the project starts.

Technical Specifications

Property	Value
Binder Type	Hybrid organic siloxane + inorganic silicate
Aggregate	Marble
Density (ready to use)	Approx. 1.9 g/cm³
Grain Size Options	1.5 mm (N-15) / 2.0 mm (N-20) — spotted texture
Coverage (hand application)	2.5 kg/m² (1.5 mm) / 3.2 kg/m² (2.0 mm) — approx. 10 m² or 7.8 m² per 25 kg tub
Vapour Permeability	V1 (high) — > 150 g/m²·d / Sd < 0.14 m to EN 15824
Water Absorption	W2 (medium) — ≤ 0.5 kg/m²·h⁰·⁵ to EN 15824
Adhesion to Substrate	≥ 0.35 MPa
Fire Classification	A2-s1,d0 (limited combustibility)
Thermal Conductivity	0.67 W/mK (λ₁₀, dry) to EN 1745:2002
Application Temperature	+5 °C to +25 °C (air and substrate)
Setting Time	12–48 hours depending on temperature and humidity
Shelf Life	12 months from production date (sealed, +1 °C to +30 °C)
Standard Compliance	EN 15824:2009 — DoP No. 125/CPR
System Approvals	ETA 06/0081 (ATLAS), ETA 06/0173 (ATLAS ROKER), AT-15-9090/2014 (ATLAS ETICS)
Colours	400+ shades per SAH Colour Scheme — select from colour picker or specify SAH code; physical sample catalogues available
Pack Size	25 kg plastic bucket / pallet: 600 kg (24 × 25 kg)
Machine Application	1.5 mm grain only — MAI 2 MULTIPUMP (6 mm nozzle, 1 bar) or GRACO RTX 1500 (6 mm nozzle)

Application and Compatibility

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. The substrate must be structurally sound, dry, level, and free from dust, oils, or old paint coatings that would block the chemical bond between the silicate binder and the mineral surface. For high-suction substrates (aerated block, old lime plaster), apply a consolidation primer first, then follow with Atlas Silkon ANX priming mass to create an even key for the finish coat — the full render primer range includes options matched to every common UK substrate type.

• EWI System Integration: When used as the finish coat over insulation boards, this render is approved within the ATLAS (ETA 06/0081), ATLAS ROKER (ETA 06/0173), and ATLAS ETICS (AT-15-9090/2014) thermal insulation systems — requiring a reinforced basecoat with alkali-resistant fibreglass mesh at 150 g/m² fully cured for three to seven days before priming and topcoat application.
• Heritage and Conservation Projects: The V1 vapour permeability and silicate-based mineral bond satisfy the breathability and material-compatibility requirements set out in BS 7913:2013 and Historic England guidance, making this render the specification that conservation officers approve most readily for listed buildings and conservation-area facades — the silicone-silicate render heritage and conservation guide covers the full selection criteria, planning documentation, and scenario-matched recommendations.
• Dark-Colour Guidance: Facades with colours above a 20 % diffuse-reflection coefficient work perfectly with this formulation across the full surface area — for colours below that threshold on insulated systems, specifying a solar-protect formulation such as CT76 for areas exceeding 10 % of the facade ensures long-term thermal stability and colour consistency on south-facing walls.
• Machine Application: The 1.5 mm grain variant is optimised for mechanical application using MAI 2 MULTIPUMP or GRACO RTX 1500 rendering units with a 6 mm nozzle at 1 bar, delivering faster coverage on large commercial or multi-storey elevations with slightly lower material consumption than hand application.

Installation Notes

The render arrives ready to use — simply stir with a low-speed mechanical mixer to unify consistency before applying with a smooth stainless-steel float at a coat thickness matching the aggregate grain size (1.5 mm or 2.0 mm). For the cleanest result, work in a "wet-on-wet" method across the entire elevation rather than allowing one section to dry before starting the next, because dried edges create visible join lines that are difficult to correct once the render has cured. Plan technological breaks at natural boundaries — corners, angles, rainwater-pipe lines, or colour junctions — and texture the freshly applied surface with circular movements using a plastic float while the render is still workable. For the best curing conditions, apply when air and substrate temperatures sit between +5 °C and +25 °C with relative humidity below 80 %, and protect the finished surface from direct sunlight, wind, and rain for 12 to 48 hours depending on conditions — the seasonal application timing guide covers the full UK weather-management protocol including winter work with Atlas Eskimo setting accelerator down to 0 °C. For a uniform colour finish across the entire facade, use tubs from the same manufacturing date on each individual surface — even factory-controlled pigments can shift fractionally between production runs, and confirming batch numbers on delivery takes a moment that protects the finished appearance under raking light.

Trade Insight: Installer's Note

I always verify substrate temperature with an infrared thermometer before committing the first tub to the wall — a forecast reading of 8 °C does not mean the shaded north elevation is above 5 °C at 07:30, and catching that difference before the render is on the wall keeps the job on programme and the finish flawless. The silicone-silicate hybrid sets slightly faster than a pure silicone in warm conditions because the mineral binder component absorbs moisture from the mix more actively, so the open time on the wall is shorter — on elevations above 20 °C, working in panels of roughly 4–5 m² at a time and texturing each panel immediately keeps the spotted pattern consistent. The orange-lid tubs are the visual identifier on site: if you are expecting silicone-silicate and the lid is not orange, check the label before opening. One 25 kg tub covers 10 m² at 1.5 mm grain by hand, and machine application actually reduces material consumption slightly because the thinner aggregate concentration achieved by the pump is sufficient for texture formation — so recalculate your order if you are switching from hand to machine mid-project. For the cleanest result, plan your scaffold lifts so you finish each full vertical drop in one pass rather than leaving a horizontal band at scaffold height, because that line becomes visible in raking light and is the most common aesthetic issue on otherwise well-executed silicone-silicate facades.

Is This Product Right for Your Project?

• Choose this render if: your wall is solid masonry with lime mortar, cellular concrete (AAC), natural stone, or any heritage substrate where V1-class breathability is required by conservation officers, building surveyors, or the building's own moisture-management needs — this is the one thin-coat system in the range that lets moisture escape the wall almost as freely as an uncoated surface while delivering hydrophobic rain protection, microfibre crack resistance, and A2-s1,d0 fire classification in a single through-coloured coat.
• Consider a different product if: your project is a standard new-build or modern-masonry retrofit where V2 permeability is sufficient — in that case, the pure silicone render range delivers the same self-cleaning performance and 25-year colour stability at a lower cost point, because the additional silicate binder is unnecessary on substrates that do not rely on outward evaporation for moisture control.
• Consider an alternative category if: the application area is below the damp-proof course, in a splash zone, or on a plinth subject to persistent ground-level impact — where a mosaic render provides the heavy-duty impact resistance and washability those conditions demand.

Frequently Asked Questions

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) on a flat, primed substrate — so a typical 80 m² cottage facade at 1.5 mm grain requires 8 tubs, plus one extra tub as a waste and detailing allowance for window reveals, corners, and pipe cut-outs. Machine application slightly reduces consumption because the pump applies a thinner aggregate concentration, but always round up to the next full tub so you can maintain the wet-on-wet technique across the entire elevation without running short and leaving a visible join line.

How do I choose and order a specific colour?

Popular lighter shades — whites, creams, and soft pastels — are available to select directly from the colour picker on this page, with each tinted option factory-mixed to your chosen SAH code for consistent colour across every tub (a small surcharge applies for tinted colours — the exact price is shown on the product page above). For the full 400+ shade SAH palette, including mid-tones and heritage earth tones, order a physical colour sample catalogue and hold the swatch against your wall under morning and afternoon daylight to confirm your choice before committing to a bulk order. Grain size affects appearance — a 2.0 mm texture casts deeper micro-shadows that can make the same pigment look marginally darker than 1.5 mm — so always confirm your shade at the grain size you plan to use on site.

Is this render suitable for listed buildings and conservation areas?

V1 vapour permeability (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 approve it more readily than polymer-only finishes for Grade II listed buildings and conservation-area properties where BS 7913:2013 and Historic England guidance require materials to be fully compatible with traditional building fabric.

Can I apply this render in cold or wet UK weather?

Standard application requires air and substrate temperatures between +5 °C and +25 °C, relative humidity below 80 %, and no rain forecast for 24 hours. Winter work can be extended down to 0 °C by adding Atlas Eskimo setting accelerator at one 0.25 kg bottle per 25 kg tub, which halves curing time and delivers rain resistance up to three times faster — keeping your schedule on track through late autumn and early spring when conditions are marginal. Scaffold netting or temporary enclosures remain best practice even with the accelerator, because the additive speeds the chemical cure but the freshly rendered surface still needs physical protection from driving rain and frost within the first 18 hours.

What makes silicone-silicate render different from pure silicone render?

The practical difference is breathability and substrate bonding. Pure silicone render achieves V2 permeability (Sd 0.14–1.4 m), which is excellent for modern masonry but restricts moisture movement enough to cause hidden damp on solid lime-mortared walls that rely on outward evaporation. This silicone-silicate hybrid achieves V1 (Sd below 0.14 m) — roughly ten times more permeable — and its inorganic silicate component forms a chemical bond with mineral substrates, so the render integrates with heritage masonry rather than forming a separate skin. For standard new-build and modern-masonry projects, pure silicone is the correct and more cost-effective choice; for heritage, AAC, and high-permeability substrates, the silicone-silicate hybrid is the specification that satisfies both the building's moisture needs and the conservation officer's requirements.

Is this render environmentally responsible?

The formulation is water-based with maximally reduced volatile organic compounds (VOC) and uses only natural marble fillers, aligning with sustainable-development manufacturing principles. The thin application rate of 2.5 kg/m² at 1.5 mm grain generates substantially less material waste per square metre than traditional sand-and-cement renders applied at 15–20 mm thickness, and the 25-year-plus through-coloured service life eliminates the recurring resource consumption of periodic repainting cycles — so the total environmental footprint over the building's life is significantly lower than thicker, shorter-lived alternatives.