CT174 Silicate-Silicone Render 1.5 mm — Crack-Resistant Hybrid Finish for UK Facades (25 kg)

Product Overview

Ceresit CT174 silicate-silicone render 1.5 mm delivers a breathable, hydrophobic facade finish that stays crack-free through decades of British weather — combining silicate mineral hardness with silicone flexibility in a single 25 kg tub covering approximately 10 m². Sourced from the premium silicone render range at Renders World, this hybrid decorative plaster is engineered for External Thermal Insulation Composite Systems (ETICS) over graphite EPS, mineral wool, or XPS insulation boards. Its double-binder formulation achieves V1-rated vapour permeability under EN 15824:2017 (so moisture passes outward freely, keeping walls dry inside) alongside W3-rated low water absorption (meaning rain beads off the surface rather than soaking in).

Available in the full Ceresit Colours of Nature palette — 516 shades organised into six curated collections including Wise & Confident, Grey Vibes, Harmonious & Balanced, Romantic & Delicate, Energetic & Positive, and Intense & Expressive — the CT174 1.5 mm finish gives your project a uniform stone-textured aesthetic with long-lasting colour stability. Through-body pigmentation means the colour runs all the way through the render mass, so minor surface scuffs do not expose a different shade underneath (unlike painted finishes that can chip or peel).

The integrated BioProtect formula provides active resistance to algae, mould, and fungi — a genuine advantage on north-facing elevations and in the damp climate zones common across England, Wales, and Scotland. Whether you are a professional renderer looking for a reliable one-coat decorative finish, a developer specifying a Ceretherm BBA-certified facade system (DoP 145/3/CPR to EN 15824:2017), or a homeowner selecting a premium facade coating that stays clean for years, CT174 provides a self-cleaning surface where rainwater carries away atmospheric dust and pollutants naturally.

Key Benefits

• Crack-Resistant Flexibility: The silicone component gives the render an elastic polymer matrix that moves with seasonal thermal expansion of your walls and insulation, keeping the facade intact through hot summers and cold winters alike (silicate renders alone can be rigid enough to develop micro-cracks, but CT174's hybrid formula compensates for substrate movement up to the normal thermal cycling range).
• Breathable Moisture Management: V1-rated vapour permeability under EN 15824:2017 lets moisture from inside the building pass outward through the render layer, keeping the wall structure dry and the internal environment healthy — your insulation system performs at its designed efficiency because moisture moves freely rather than accumulating.
• Self-Cleaning Surface: Low surface tension means rainwater sheets across the finish rather than pooling in the texture, flushing away urban dust, pollen, and atmospheric pollutants — reducing the need for manual facade cleaning over the life of the building.
• 516 Factory-Mixed Colours: The full Ceresit Colours of Nature palette is available as factory-tinted, through-body colour, giving you design freedom from subtle off-whites through bold earth tones to deep contemporary shades — each pigment UV-stabilised to resist fading.
• BioProtect Anti-Microbial Shield: Active biocidal agents embedded in the render mass inhibit algae, mould, and fungal colonisation, keeping the facade visually clean for longer, even in sheltered, damp-prone areas where biological growth typically appears within 2–3 years on unprotected surfaces.
• Versatile Application Method: Suitable for both hand trowelling and machine spraying, so professional renderers can choose the method that best fits their project scale — from a single domestic elevation to a multi-block housing development.

Technical Specifications

Property	Value
Binder Type	Silicate-silicone hybrid resin
Grain Size	1.5 mm (stone texture)
Pack Size	25 kg
Coverage Rate	Approx. 2.5 kg/m² (~10 m² per tub)
Density	Approx. 1.7 kg/dm³
Vapour Permeability	V1 (High) — EN 15824:2017
Water Absorption	W3 (Low) — EN 15824:2017
Adhesion to Substrate	≥ 0.35 MPa
Application Temperature	+5 °C to +25 °C (air and substrate)
Colour Range	Full Ceresit Colours of Nature palette (516 shades)
Biological Protection	BioProtect formula (algae, mould, fungi)
Standard Compliance	EN 15824:2017 (DoP 145/3/CPR) / Ceresit Ceretherm BBA-certified system component
Texture Type	Stone (aggregate grain)
Primer Required	Ceresit CT 16 quartz primer (mandatory)

Application & Compatibility

CT174 silicate-silicone render integrates directly into Ceresit Ceretherm ETICS assemblies and pairs seamlessly with the broader Renders World system range to give your project a single-source specification from insulation board to decorative finish. For a complete rendering system, prime the reinforced basecoat with a silicone render primer — specifically Ceresit CT 16 quartz primer — and embed Atlas 150 g/m² fibreglass mesh in the basecoat layer to create the stable, crack-resistant substrate this render is designed to bond with.

• Compatible Insulation Types: Graphite EPS boards, standard EPS, mineral wool slabs, and XPS boards within ETICS assemblies — making it suitable for new-build facades, retrofit solid-wall insulation, and over-cladding projects across the UK.
• Substrate Versatility: Performs best on reinforced basecoats over masonry, concrete, and existing well-bonded mineral renders, provided the surface is clean, dry, and structurally sound.
• Mandatory Priming Step: Applying Ceresit CT 16 quartz primer at least 24 hours before rendering regulates suction and creates a keyed surface, so the CT174 bonds evenly across the entire elevation for a uniform, blemish-free finish.
• Weather Conditions: Scheduling application when air and substrate temperatures are between +5 °C and +25 °C gives the render ideal curing conditions — read more about planning your rendering schedule in our guide to when you can apply silicone render in the UK.

Installation Notes

Preparing the surface properly before you start is the single most valuable step for a flawless CT174 finish. Ensure the primed basecoat is fully cured (minimum 24 hours after CT 16 application), and stir the tub contents with a low-speed mechanical mixer until the consistency is uniform before loading a hawk or machine hopper. For the cleanest joins, work each elevation in a continuous wet-on-wet pass rather than stopping and starting mid-wall — this maintains a seamless stone texture across the full surface.

Apply at the thickness of the 1.5 mm grain using a stainless-steel float held at a slight angle, then texture immediately with circular movements using a plastic float to produce the characteristic densely packed aggregate finish. A quick check of a 48-hour weather forecast before you begin is all it takes to ensure rain-free curing for the first 24 hours, giving the render a clean, uninterrupted film-formation period for maximum durability.

Trade Insight: Installer's Note

I always make sure the CT 16 primer has had a full 24 hours to cure before applying CT174 — a properly keyed surface makes the render pull onto the wall evenly, and the 1.5 mm grain practically floats into texture with minimal effort once the suction is right. On larger elevations, two renderers working in tandem keeps the wet edge alive right across the wall, which is how you get that perfectly uniform stone finish with zero lap marks. CT174 has a noticeably shorter open time than pure silicone renders — roughly 15–20 minutes before the silicate binder starts to firm — so I work in sections no wider than arm's reach and texture immediately rather than floating a full bay first, which keeps the stone grain consistent across the entire elevation.

Is This Product Right for Your Project?

• This is the right choice if you need a breathable, crack-resistant decorative finish for an ETICS facade in the UK climate — CT174's hybrid silicate-silicone formula delivers V1 vapour permeability, W3 water resistance, and a self-cleaning stone texture in any of 516 colours, making it a strong all-round specification for domestic and commercial elevations alike.
• Need a finer grain for machine-only application? The CT174 machine-applied 1.0 mm render in the same silicate-silicone range delivers the same double-binder performance with a smoother, finer stone texture and a lower coverage rate of approximately 1.8–2.1 kg/m², optimised for professional spray rigs on large-scale projects.
• Looking for heavy-duty plinth protection? High-impact areas below DPC benefit from the mechanical resistance of a dedicated mosaic render for plinths, which provides a resin-bound aggregate finish engineered to withstand ground-level splashing, foot traffic, and physical contact.

Frequently Asked Questions

How many tubs of CT174 1.5 mm do I need for my project?

Each 25 kg tub covers approximately 10 m² at the standard application rate of 2.5 kg/m², so a 100 m² facade typically requires 10–11 tubs. Adding 5–10 % for detailing around window reveals, corners, and site waste ensures you have enough material to complete the job without interruption — use our render coverage calculator to work out the precise quantity for your wall area.

What colours are available for CT174?

CT174 is available in the complete Ceresit Colours of Nature palette — 516 factory-mixed shades spanning six curated collections: Wise & Confident (warm neutrals), Grey Vibes (contemporary greys), Harmonious & Balanced (nature-inspired mid-tones), Romantic & Delicate (soft pastels), Energetic & Positive (vibrant accents), and Intense & Expressive (deep, bold hues). Every colour is through-body pigmented and UV-stabilised, so the shade you choose remains consistent for the long term. Browse the full selection with the Renders World render colour charts and catalogues to find the exact tone for your facade.

Can I use CT174 with dark colours on south-facing walls?

Dark shades with a low brightness value (below HBW 25) absorb more solar energy, which can raise surface temperatures on sun-exposed elevations. For the most reliable result with very dark colours on south- or west-facing walls, Ceresit's CT 76 Solar Protect render is specifically formulated with nano-scale heat-reflective pigments to manage thermal stress. For mid-range and lighter shades, CT174 performs confidently on any orientation thanks to its flexible silicone component, which accommodates the thermal cycling that occurs throughout the day.

Is CT174 an environmentally responsible choice?

CT174 is a water-based formulation with very low volatile organic compound (VOC) content, so it produces minimal fumes during application and is safer for installers working on enclosed scaffold. The thin 1.5 mm application rate uses approximately 2.5 kg/m² of material — a fraction of the 30–40 kg/m² that traditional sand-and-cement renders require at 15–20 mm thickness — which significantly reduces material consumption and site waste per square metre. Through-body colour eliminates the recurring resource use and emissions of periodic repainting cycles, and Ceresit's Eco Bucket packaging uses up to 62 % post-consumer recycled polypropylene.

Does CT174 need painting after application?

CT174 is a through-coloured render, which means the pigment is distributed throughout the entire mass rather than applied as a surface coating. This built-in colour will not peel, flake, or require repainting, giving you a maintenance-free decorative facade that retains its appearance for years. The self-cleaning surface ensures that atmospheric dust is washed away naturally by rainfall, keeping the finish looking fresh with no manual intervention.

What primer must I use before applying CT174?

Ceresit CT 16 quartz primer is the mandatory preparatory coat for CT174. Applying CT 16 to the cured reinforced basecoat at least 24 hours before rendering creates an evenly keyed, suction-regulated surface that ensures the silicate-silicone finish bonds uniformly across the full elevation. This primer step is essential for achieving a consistent stone texture and long-term adhesion — it takes roughly 15–20 minutes per coat and covers approximately 5 m² per litre.