Description
Atlas Cerplast 25 kg is a BBA-certified quartz-aggregate priming mass that creates the mechanical key between your cured basecoat and decorative render topcoat, achieving ≥1.0 MPa adhesion to concrete and covering approximately 75 m² per bucket at 0.3 kg/m². Stocked in the wider exterior render primer range, this trade-sized pack is sized for full-house facade jobs ahead of Atlas thin-coat silicone render systems on EPS, XPS, mineral wool, and traditional masonry substrates.
Where Atlas Cerplast 25 kg Performs Best — UK ETICS Systems and Substrates
Atlas Cerplast 25 kg sits at the grip-coat stage of a certified Atlas ETICS build-up — applied to the cured reinforcement basecoat and to traditional masonry surfaces before the decorative render topcoat, where its acrylic resin and fine quartz aggregate deposit a rough, sand-textured film that the wet render physically holds onto rather than relying on chemical adhesion alone. The same primer works on poured concrete, cement and lime plasters, brick and block masonry, plasterboard, and cured EWI basecoats over EPS, XPS, or mineral wool insulation, so one product covers virtually every wall type on UK new-build and renovation programmes.
The 75 m² coverage from a single 25 kg bucket suits full-house and multi-elevation jobs where stopping to reorder mid-project would lose a day on the scaffold. Atlas Cerplast holds BBA Certificate 13/5018 (Atlas ETICS system) and ETA 06/0081, giving developers and Building Control documented evidence that every layer of the facade build-up is part of a tested, certified assembly. For the detailed pre-render priming method, the quartz primer application guide sets out tool selection and weather planning for UK conditions.
Why Trade Specifiers Choose Atlas Cerplast 25 kg
- Permanent Mechanical Grip (≥1.0 MPa to Concrete): Fine quartz aggregate deposits a rough, sand-textured surface that gives the decorative render a physical bond exceeding 1.0 MPa on concrete, independently verified under ETA 06/0081 — so the topcoat stays locked through freeze-thaw cycles, thermal movement, and decades of UK weather.
- Full-House Coverage in One Bucket: Each 25 kg bucket covers approximately 75 m² at 0.3 kg/m², enough for a typical three-bedroom semi-detached elevation in a single container — fewer mid-job reorders and simpler quantity planning on larger schemes.
- BBA + ETA Certified System Compliance: Listed under BBA Certificate 13/5018 and ETA 06/0081 within the Atlas ETICS insulation system, so every layer from substrate to topcoat carries documented approval for Building Control, warranty providers, and architect specifications.
- True Colour Accuracy via SAH Tinting: The white base accepts tinting to up to 400 shades through the SAH colour system, allowing the primer to be matched to the chosen render topcoat — masking the basecoat tone and preventing show-through on pastel and mid-tone finishes.
- Same-Day Workflow (4–6 Hour Drying): A 4–6 hour drying window at +5 °C to +30 °C lets you prime in the morning and render the same afternoon, keeping the scaffold-hire programme on schedule.
- Six-Month Weather Protection if Project Pauses: The cured primer film forms a temporary weather barrier that protects the primed facade for up to six months between priming and rendering — useful when bad weather or trade-sequencing delays the topcoat stage.
- Universal Substrate Compatibility: Performs on concrete, cement and lime plasters, brick and block masonry, plasterboard, and EWI basecoats over EPS, XPS, or mineral wool — one product covers the full preparation spectrum on UK projects.
Technical Specifications — Atlas Cerplast Data Sheet Highlights
| Property | Value |
|---|---|
| Product Type | Quartz-aggregate priming mass (ready-to-use) |
| Base | Acrylic resin + fine quartz aggregate |
| Density | ~1.5 g/cm³ |
| Adhesion to Concrete | ≥1.0 MPa |
| Coverage Rate | ~0.3 kg/m² (75 m² per 25 kg bucket) |
| Drying Time | 4–6 hours (standard conditions) |
| Application Temperature | +5 °C to +30 °C (substrate and ambient) |
| Application Method | Roller, brush, or airless spray |
| Colour | White (tintable to up to 400 shades via SAH system) |
| Pack Size | 25 kg plastic bucket (15 kg pack also available) |
| BBA Certificate | 13/5018 (Atlas ETICS system) |
| ETA | 06/0081 |
| NSAI Certificate | 10/0347 |
| Shelf Life | 12 months from production date (sealed, frost-free storage) |
| Storage Conditions | Sealed container, +5 °C to +25 °C; protect from frost and direct sunlight |
| Compatible Topcoats | Atlas silicone, acrylic-silicone, mineral, silicone-silicate, mosaic DEKO M |
| Compatible Substrates | Concrete, cement/lime plasters, brick/block masonry, plasterboard, cured EWI basecoats (EPS, XPS, mineral wool) |
| Manufacturer | Atlas Sp. z o.o. |
How to Apply Atlas Cerplast — Substrate Prep, Roller Technique, and System Sequencing
Atlas Cerplast performs at full specification when applied to a clean, stable substrate free from dust, loose material, oil, and efflorescence between +5 °C and +30 °C — the quartz aggregate needs direct contact with a sound surface to develop its ≥1.0 MPa bond. New cement plasters need a minimum curing time of one week per centimetre of thickness; poured concrete needs at least 28 days. On dusty or highly absorbent masonry, a consolidation pass with Atlas Uni-Grunt stabilises the pore structure before the Cerplast coat goes on, so the quartz primer sits on a uniform surface rather than soaking unevenly into porous areas.
Stir the bucket thoroughly with a low-speed drill and clean paddle for 2–3 minutes before use to redistribute settled aggregate, then apply a single even coat with a medium-nap roller (18–25 mm pile) on flat elevations, a wide masonry brush for reveals and detailing, or an airless sprayer with an abrasive-rated tip on large commercial facades. Work in sections no wider than one scaffold lift to maintain a wet edge and avoid lap marks. Allow the full 4–6 hour drying window before the render topcoat; on cool or humid UK days, extending the wait to a full overnight dry gives the topcoat the best foundation. Atlas Cerplast is supplied ready to use — never dilute, never add other materials, and never apply over a damp or contaminated surface.
Installation Notes — Site Conditions, Drying Window, and Atlas System Sequence
Prime the entire elevation before moving on rather than working in patches, because uniform priming across the full wall equalises suction and prevents drying-speed differences that can appear as colour banding in the finished topcoat. Start on the shaded side of the building and follow the shade around rather than applying in direct sunlight, which can skin the surface before the aggregate has bedded in. Check substrate temperature with an infrared thermometer on shaded and north-facing elevations rather than relying on the air reading alone — surface temperature can sit several degrees below the ambient figure on cool mornings.
On a full Atlas ETICS build-up, Cerplast follows the cured reinforcement basecoat and precedes the decorative render — Atlas Uni-Grunt consolidates the bare masonry first, EPS or mineral wool boards bond with a system adhesive, a cementitious basecoat with embedded fibreglass mesh forms the reinforcing layer, then Cerplast deposits the quartz key, and finally an Atlas silicone, acrylic-silicone, mineral, or mosaic topcoat completes the facade. Clean tools with water immediately after use, before the resin cures permanently onto roller fibres and brush bristles. Store unused product sealed in its original container at +5 °C to +25 °C, protected from frost — frozen primer cannot be recovered by thawing.
Pro Tips From UK Installers Using Atlas Cerplast
- Tint to the topcoat shade on every project: Even mid-tone greys can flash the white primer through at the thinnest points of a 1.5 mm grain texture, so SAH-tinting the Cerplast to match the render shade is worth the small extra step on every job, not just on light colours.
- Cross-hatch roller pattern: Apply with a long-pile roller in a deliberate cross-hatch pass — horizontal first, then vertical — to distribute the quartz aggregate more evenly than a single-direction roll, giving the topcoat noticeably more consistent grip across the elevation.
- Decant in summer heat: On days above +25 °C, keep the main bucket in the shade and decant into a smaller tray every half hour to maintain a consistent working consistency from first roller stroke to last.
- Plan two buckets for a full-perimeter job: One 25 kg bucket covers front and rear elevations of a typical semi-detached property with material to spare; two buckets give comfortable coverage including gable ends and reveals without rationing.
- Use IR temperature check on shaded walls: A surface thermometer reading on north and east elevations catches the times when the wall is still below +5 °C even though the air has warmed up, preventing application below the temperature window.
Is Atlas Cerplast 25 kg Right for Your Project?
- Yes — for full-house Atlas ETICS facades and multi-elevation jobs: The 75 m² coverage per bucket keeps the work moving without mid-project reordering, the BBA + ETA certification satisfies Building Control and warranty providers, and the SAH-tintable white base masks the basecoat under any topcoat shade.
- Need a smaller quantity for a single elevation or patch repair? The Cerplast 15 kg bucket covering 45 m² uses the identical formulation in a mid-size pack, so you get the same adhesion, drying time, and tintability without over-ordering on smaller jobs.
- Specifying a Ceresit render system instead? The certified quartz primer for CT74, CT76, and CT174 topcoats is the Ceresit CT16 Quartz Primer 10 L — keeping every layer within the same approved system gives the strongest warranty position and the simplest Building Control documentation.
- Working on dusty or deteriorated masonry first? Apply Atlas Uni-Grunt 5 kg as the consolidation pass before Cerplast — the two-coat sequence adds less than £1 per m² and significantly improves bond reliability across mixed or weathered substrates.
FAQ — Atlas Cerplast Coverage, Compatibility, and Certification
How many square metres does the 25 kg bucket cover?
Each 25 kg bucket covers approximately 75 m² at the standard 0.3 kg/m² consumption rate on normally absorbent substrates. Highly porous masonry or rough-textured basecoats can draw slightly more product on the first few square metres, so ordering 10 % extra on older brick or blockwork elevations gives you enough material to maintain consistent coverage without stretching the coat too thinly. A splash test on a representative wall section confirms whether the substrate is at the standard rate or the higher end before placing a full order.
Is Atlas Cerplast compatible with non-Atlas render topcoats?
Atlas Cerplast is certified within the Atlas ETICS system (BBA Certificate 13/5018) for use beneath Atlas silicone, acrylic-silicone, mineral, and mosaic renders. Using it beneath a non-Atlas topcoat falls outside the tested and certified system assembly, which may affect the manufacturer's warranty coverage. For projects specifying Ceresit render systems, the certified quartz primer is Ceresit CT16 — keeping every layer within the same approved system gives contractors and developers the strongest warranty position and the simplest Building Control documentation pathway. The full primer-by-system selection is covered in the primer selection guide.
Is Atlas Cerplast safe to use on occupied buildings?
Atlas Cerplast is a water-based, solvent-free formulation that produces minimal odour during application and does not release harmful fumes while curing, so it suits work on occupied homes, schools, and care buildings without specialist extraction or protective equipment. Once the primer film dries fully it is vapour-permeable — the wall continues to breathe rather than trapping moisture — and chemically inert. Unused liquid product stays in its sealed original container for return to a local recycling centre as a water-based paint product; fully hardened residue in the bucket disposes of as standard construction waste.
What happens if the primed wall gets rained on before the render coat?
Once fully cured (4–6 hours under standard conditions), the Cerplast film forms a temporary weather barrier that protects the primed facade for up to six months against rain, frost, and airborne dust. A rain shower after the primer has dried does not compromise the quartz aggregate bond — allow the surface to dry fully again before applying the topcoat. Checking a 48-hour weather forecast before priming and scheduling the render coat for the next dry day gives the primer ideal conditions to cure undisturbed and the topcoat a clean, dry surface to bond to.
Do I need a separate consolidating primer as well as Cerplast?
On clean, stable substrates with normal porosity — such as a freshly cured EWI basecoat or sound new blockwork — Cerplast alone provides the grip coat the render needs. On older, dusty, or highly absorbent masonry, applying a deep-penetrating consolidator such as Atlas Uni-Grunt first stabilises the pore structure and evens out suction; Cerplast then goes on top to create the quartz aggregate key for the topcoat. This two-coat sequence adds less than £1 per m² to the project cost while significantly improving bond reliability across mixed or deteriorated substrates.
What is the shelf life and storage requirement?
Atlas Cerplast carries a 12-month shelf life from production date when stored sealed and upright in the original container at temperatures above +5 °C and below +25 °C, protected from frost and direct sunlight. Frozen primer cannot be recovered by thawing — the acrylic resin and aggregate separate irreversibly — so winter storage on unheated sites or in vans overnight needs a frost-protected arrangement above +5 °C.
Technical Documentation — Atlas Cerplast TDS, BBA, and ETA Resources