Description
Ceresit CT 177 Mosaic Render 25 kg — Trade-Volume Quartz Plinth Finish Covering 6 m²
Product Overview
Ceresit CT 177 mosaic render in a 25 kg bucket covers approximately 6 m² of plinth, reveal, or entrance surround at a yield of 4.0 kg/m², delivering a resin-bound coloured quartz finish with Category I impact resistance under ETAG 004 — the highest classification for decorative thin-layer plasters. Sitting within the mosaic renders collection at Renders World, this trade-volume pack is the professional choice for full-house plinths and multi-property projects where consistent batch continuity across large areas reduces material wastage and site downtime.
Your plinth resists driven rain, mechanical knocks, and biological growth at ground level — precisely the zone conventional thin-coat renders and masonry paints find hardest to protect — because the formulation blends transparent acrylic resin with 1.0–1.6 mm coloured quartz aggregate to create a dense, non-porous mosaic surface. Colour is embedded within the aggregate grains rather than sitting on the surface as a paint film, so there is no coating to peel, chalk, or fade under UV exposure. For architects and developers, CT 177 holds European Technical Assessments across multiple Ceresit Ceretherm insulation systems and a Declaration of Performance (No. 00469) under EN 15824:2017 (current edition), confirming W3 water absorption, V2 vapour permeability, and Category I impact resistance within certified EWI build-ups — in plain terms, this means the product is independently tested and certified to keep water out, let walls breathe, and withstand everyday knocks.
Key Benefits
- Impact-Proof Plinth Protection: Your plinth stays intact against lawnmower strikes, bicycle wheels, and foot traffic because the dense quartz-resin matrix achieves Category I impact resistance (ETAG 004) — the highest thin-layer classification, meaning everyday knocks are absorbed without cracking or chipping the surface.
- Rain Runs Off, Moisture Escapes: Ground-level splashback and driven rain bead away from the surface rather than soaking in, thanks to a W3 water-absorption rating (w ≤ 0.1 kg/m²·h⁰·⁵ under EN 15824:2017). At the same time, V2 vapour permeability (Sd 0.14–1.4 m) allows trapped moisture to migrate outward through the render, preventing damp build-up behind the finish — essential for solid-wall substrates without a cavity.
- Colour That Never Needs Repainting: The mosaic finish retains its appearance year after year because pigment is locked inside each quartz grain, not applied as a surface film. There is no paint layer to peel, chalk, or fade under UV, which eliminates the cyclical repainting cost that conventional masonry paint demands over a 25-year building lifecycle.
- Crack-Free Finish Through UK Seasons: The flexible acrylic-resin binder stretches and contracts with seasonal substrate movement (the transparent resin matrix absorbs micro-movement rather than resisting it), so the surface stays seamless where a rigid cement-based plinth coating would develop hairline fractures during freeze-thaw cycles.
- Easy Mud and Pollution Clean-Up: Dirt from road spray, splashback, and air pollution rinses off with a garden hose or soft-pressure wash, keeping plinths presentable between maintenance cycles and reducing long-term upkeep to a simple seasonal rinse.
- Certified EWI System Compatibility: CT 177 holds European Technical Assessments across Ceresit Ceretherm Popular, Classic, Premium, Visage, and Wool Classic systems, giving architects, developers, and Building Control a clear compliance pathway when specifying the plinth zone of an insulated facade.
Technical Specifications
| Property | Value |
|---|---|
| Pack Size | 25 kg bucket |
| Approximate Coverage | ~6 m² per bucket |
| Yield | ~4.0 kg/m² |
| Grain Size | 1.0–1.6 mm |
| Density | ~1.75 kg/dm³ |
| Base | Aqueous synthetic resin dispersion with coloured mineral fillers |
| Adhesion (EN 15824:2017) | 0.6 MPa |
| Water Absorption (EN 15824:2017) | W3 — w ≤ 0.1 kg/m²·h⁰·⁵ |
| Vapour Permeability (EN 15824:2017) | V2 — Sd 0.14–1.4 m |
| Impact Resistance (ETAG 004) | Category I |
| Interlayer Adhesion After Ageing (ETAG 004) | ≥ 0.08 MPa |
| Water Absorption 24 h (ETAG 004) | < 0.5 kg/m² |
| Thermal Conductivity (EN 15824:2017) | λ = 0.61 W/(m·K) |
| Application Temperature | +10 °C to +25 °C |
| Preliminary Drying Time | ~30 min |
| Rain Resistance | ~3 days |
| Fire Reaction (EN 13501-1) | B-s1,d0 / B-s2,d0 (system-dependent) |
| Declaration of Performance | No. 00469 (EN 15824:2017) |
Application & Compatibility
Mosaic render delivers its full impact resistance and colour retention when applied over a correctly prepared, load-bearing substrate primed with a quartz-based primer such as Ceresit CT 16 or Atlas Cerplast. The primer creates a keyed surface for the acrylic resin to grip and evens out substrate suction — tinting the primer close to the mosaic aggregate colour prevents the grey basecoat from telegraphing through the transparent binder, giving you a richer, more uniform finish from the first pass.
- Recommended Substrates: Mosaic render bonds securely to most common UK wall types — brick, block, concrete, and previously rendered surfaces — provided the substrate is stable and dry. Specifically, it works on mature cement or cement-lime plasters (28+ days old), concrete (3+ months old, moisture ≤ 4 %), and reinforced basecoat layers made with Ceresit ZU, CT 85, CT 190, or CT 100 mortar (3+ days old). Gypsum substrates are suitable indoors only and require Ceresit CT 17 deep-penetration primer before the CT 16 quartz coat.
- EWI Plinth Zone Integration: CT 177 is the recommended decorative finish for the plinth zone (typically 300–600 mm above ground level) of external wall insulation systems built with XPS or high-density EPS boards, providing combined impact protection and water resistance exactly where the facade meets the ground.
- HBW Colour Guidance for Large Areas: Lighter aggregate blends with a light-reflectance value (HBW) of 20 or above work on any facade area without restriction. Darker colours below HBW 20 perform best on smaller zones — plinths, reveals, architectural accents — because large south-facing elevations in dark mosaic can absorb enough solar heat to warm the insulation layer beneath. Our mosaic render plinth application guide covers safe colour-zoning strategies for mixed-finish projects.
Installation Notes
Achieving a seamless, batch-consistent mosaic finish across a full plinth elevation starts with stirring each 25 kg bucket on a slow-speed drill fitted with a basket mixer until the resin and aggregate reach a homogeneous consistency. A maximum of 250 ml of clean water per 25 kg may be added if the consistency needs adjustment, but exceeding that limit prevents the material from performing correctly. Apply the mixed material with a stainless-steel float in a single direction at approximately 1.5 × grain thickness (roughly 2.0–2.5 mm wet), working wet-on-wet across the full elevation to eliminate visible lap joints — the resin begins curing within approximately 30 minutes, so planning each wall as one uninterrupted session gives you the even, unpatterned surface clients expect. For the cleanest restart when a break mid-wall is unavoidable, mask a straight line with adhesive tape, render up to it, and remove the tape while the material is still fresh — rather than attempting to blend into a partially cured edge, which leaves a visible seam. Protect the finished surface from rainfall for at least three days with scaffold netting or tarpaulins to ensure a clean, even cure free of the temporary milky haze that can occur when uncured resin contacts water.
Trade Insight / Installer's Note
The 25 kg bucket is the trade format for a reason — on a standard semi-detached plinth of roughly 15–18 m², three to four buckets from the same production batch give you consistent aggregate colour and binder viscosity from corner to corner, with no visible batch-line between sections. Matching the CT 16 quartz primer colour to the mosaic aggregate shade before you start eliminates the grey shadow that telegraphs through the transparent resin on lighter blends, so the finish reads true to the colour chart from the first coat. Avoid circular trowelling — a straight, consistent float direction lets the aggregate settle into its natural random pattern and prevents the swirl marks that clients notice in low sunlight. Keeping unopened buckets between +5 °C and +25 °C and sealing opened containers overnight preserves the resin's workability for the next session — so you get the same consistency from the first bucket to the last.
Is This Product Right for Your Project?
- Yes — for full-house plinths and trade-volume jobs: The 25 kg Ceresit CT 177 bucket is the right specification when you need approximately 6 m² of impact-resistant, colour-permanent mosaic finish per pack — ideal for complete house plinths, multi-elevation entrance surrounds, and any project where batch-consistent coverage across large areas matters.
- Need a smaller pack for repairs or feature panels? The Ceresit CT 177 mosaic render in a 10 kg bucket covers approximately 2.5 m² using the same formulation at the same 4.0 kg/m² yield — the practical choice for small repairs, single reveals, and decorative accent panels where a full 25 kg bucket would leave surplus material.
- Looking for a self-cleaning finish across main wall elevations? Above plinth height, where impact resistance is less critical than breathability and self-cleaning performance, a silicone or silicone-silicate topcoat offers superior vapour permeability and hydrophobic action over broad exposed surfaces. Our guide to decorative facade finishes explains how to pair mosaic render below the DPC line with a silicone topcoat above for a complete dual-finish facade specification.
Frequently Asked Questions
How many 25 kg buckets of mosaic render do I need for a typical house plinth?
Three to four buckets cover a standard semi-detached plinth of roughly 15–18 m² at the confirmed yield of approximately 4.0 kg/m², where each 25 kg bucket finishes around 6 m². Measure the full perimeter length, multiply by your plinth height (typically 300–600 mm), and add 5–10 % for corners, reveals, and normal site wastage. Ordering from the same production batch across all buckets ensures uniform aggregate colour and binder consistency from one end of the elevation to the other.
What primer should I use before applying Ceresit CT 177 mosaic render?
Use Ceresit CT 16 quartz primer — it creates a keyed surface that gives the mosaic resin a reliable grip and evens out substrate suction, so the finished colour reads true across the full elevation. CT 16 is the correct preparation for all mineral substrates, concrete, and reinforced basecoat layers. Tinting the primer close to your chosen aggregate colour ensures the grey basecoat stays invisible behind the transparent binder. For gypsum substrates (interior applications only), applying Ceresit CT 17 deep-penetration primer first and then CT 16 over the top gives you the adhesion and suction control the resin needs for a durable bond.
Can I apply mosaic render below +10 °C in winter?
Both air and substrate temperature must remain between +10 °C and +25 °C throughout application and for approximately three days afterwards while the acrylic resin cures — staying within this range ensures full cross-linking, which is what produces the hard, weather-resistant, colour-stable surface. In practice, the UK's April-to-October window gives six to seven months of reliable application conditions; fully sheeting the scaffold and maintaining relative humidity below 80 % extends that window into the shoulder months and keeps surface condensation from interfering with the cure.
Is mosaic render breathable enough for solid-wall properties without a cavity?
Moisture trapped in a solid masonry wall migrates outward through the render rather than accumulating behind it, which is exactly the performance solid-wall properties require. Ceresit CT 177 achieves a V2 vapour-permeability rating (Sd 0.14–1.4 m under EN 15824:2017), confirming that water vapour passes through the coating at a rate compatible with dense-brick and stone substrates. For elevations where maximum breathability is the overriding priority, a silicone or silicone-silicate render offers a lower Sd value across broad areas — but at the plinth zone specifically, the superior impact resistance and rainwater repellency of mosaic render outweigh the marginal vapour-permeability difference.
How do I keep a mosaic-rendered plinth clean over the long term?
A seasonal garden-hose rinse is all most plinths need to stay fresh — the dense, low-porosity quartz surface naturally resists dirt adhesion and biological colonisation more effectively than open-textured finishes. North-facing sections shaded by vegetation may develop green algae over several years; applying a professional biocidal wash every two to three years stops spores from establishing before they become visible, and if growth does appear, treating with a specialist algae remover and a soft brush — rather than high-pressure jetting — preserves the resin binder and keeps the aggregate surface intact for the long term.