Defining silicone render
Silicone render is a modern, ready‑mixed thin‑coat render that uses silicone polymers in the binder to create a façade finish that is both hydrophobic (water‑repellent) and vapour‑permeable (breathable). It is typically supplied as a through‑colour top coat in a range of grain sizes (e.g., 1.0 – 3.0 mm), applied over a suitable base coat or EWI system.
What makes it different?
- Repels rain while letting internal moisture escape.
- Flexible matrix mitigates hairline cracking.
- Through‑colour pigments for long‑lasting aesthetics.
- Excellent compatibility with EWI systems.
Typical components
- Silicone resin binder
- Selected aggregates (grain size defines texture)
- UV‑stable pigments
- Additives for flexibility & workability
Pro tip: Match the grain size to the architectural style and substrate flatness—1.5 mm is a popular balance of coverage, texture and dirt‑shedding.
How silicone render works
The “plug‑and‑breathe” mechanism
Silicone particles form a micro‑thin, hydrophobic film that plugs capillaries in the render, stopping liquid water ingress. At the same time, the matrix remains vapour‑open, allowing water vapour to breathe outwards—reducing damp, mould risk and freeze‑thaw damage.
Thickness, texture & grain size
- Thickness: usually the same as the chosen grain size (≈1.0 – 3.0 mm).
- Texture: floated finish; finer grains look smoother, coarser grains hide minor substrate irregularities.
- Colour: through‑colour finish keeps its tone longer and reduces repainting cycles.
Key benefits of silicone render
Weather & water resistance
Rain beads and runs off; reduced absorption limits efflorescence and frost damage.
Breathability
Vapour‑permeable structure lets walls dry out naturally—great for solid walls and retrofits.
Flexibility
Polymer modification helps the finish accommodate minor movements, minimising hairline cracks.
Long‑lasting colour
UV‑stable, through‑colour pigments mean fewer repaints and a more consistent façade over time.
Low maintenance
Hydrophobic, dirt‑shedding surface supports a self‑cleaning effect from rainfall.
Ideal with EWI
Complements EWI by protecting insulation and reducing cold bridges at the surface.
When & where to use silicone render
New build vs renovation
- New builds: finishing coat over base/mesh or EWI boards for a sleek, durable façade.
- Retrofit: excellent for moisture‑challenged buildings; breathable yet protective.
Compatible substrates
- Brick, block and concrete masonry
- Render carrier boards & EWI boards (EPS, mineral wool, phenolic)
- Sound existing render (after correct prep)
Exposure & climate
- Coastal zones with wind‑driven rain
- High rainfall or freeze‑thaw regions
- Urban façades exposed to soiling and pollutants
Silicone render vs other render types
Quick verdict: While silicone render costs more upfront than sand/cement or acrylic, its performance, durability and reduced maintenance often make it the best long‑term value.
How to apply silicone render (Step‑by‑Step)
- Preparation: Clean substrate, remove loose material, repair defects, ensure dry and within temperature range.
- Base coat & mesh (if needed): On EWI or uneven substrates, apply base adhesive and embed fibreglass mesh. Level the surface.
- Primer: Use a system‑compatible primer (e.g., silicone‑quartz) to improve adhesion and colour uniformity.
- Top coat application: Apply to the grain thickness (≈1.0–3.0 mm). Float to achieve uniform texture. Work wet‑to‑wet on full elevations.
- Curing & protection: Protect from rain/frost during curing; avoid rapid drying in strong sun or wind.
- After‑care: Inspect for uniformity; schedule gentle cleaning as required over the life cycle.
Always follow the manufacturer’s data sheet for exact mixing (if applicable), drying times and weather limitations.
Costs, coverage, lifespan & maintenance
- Coverage: a typical 25 kg bucket of 1.5 mm grain covers ~8 – 10 m² (coarser grains cover less).
- Lifespan: with correct installation and care, expect 15–30+ years of service.
- Maintenance: minimal – rain often provides a self‑cleaning effect; occasional low‑pressure rinses may be used.
- Costs: higher materials and skilled labour vs traditional render, often offset by fewer repaints/repairs over time.
Potential drawbacks & considerations
- Higher upfront cost: premium chemistry and installers’ expertise come at a price.
- Skilled application: finish quality depends on experienced tradespeople and correct weather conditions.
- Heritage constraints: not always suitable for listed buildings where lime renders are required.
- Sustainability: evaluate lifecycle impacts vs performance and reduced maintenance cycles.
FAQ
Most silicone renders are applied at roughly the grain size – commonly 1.5 mm for a balanced texture and coverage.
Yes, if the existing surface is sound, clean and correctly primed. Otherwise remove or repair failing areas first.
Usually no—many conservation bodies require lime‑based systems. Confirm with the local authority or a conservation specialist.
Most façades stay clean via rainfall. For stubborn soiling, use a gentle, low‑pressure water rinse. Avoid harsh chemicals or abrasive tools.
Silicone render is through‑coloured and offered in a wide palette with grain sizes typically from 0.5 to 3.0 mm.
If you need a façade finish that is durable, breathable and water‑repellent, silicone render is a top contender. It shines on modern builds and retrofits alike – especially when paired with EWI. While it costs more upfront, the lifecycle benefits – stable colour, fewer cracks, minimal maintenance – make it a smart investment for many projects.