Description
Cerplast 15kg is the one-elevation bucket of Atlas Cerplast, the ready-to-use quartz key coat that goes over a cured basecoat so thin-coat render has a rough, evenly absorbent surface to grip. The primer is the same as in the 25 kg bucket — only the amount differs. One 15 kg bucket primes about 43–50 m², enough for a gable, an extension wall, a garage or a repair. Both sizes sit in the Renders World render primer range.
How Much Wall a Cerplast 15kg Bucket Primes
| Consumption | Where the figure comes from | Cerplast 15kg covers |
|---|---|---|
| 0.25 kg/m² | Bottom of the BBA key-coat band | About 60 m² |
| 0.30 kg/m² | Technical sheet average | About 50 m² |
| 0.35 kg/m² | Top of the BBA key-coat band | About 43 m² (42.9) |
Plan on 43 m² per Cerplast 15kg and the margin is on your side. A 40 m² gable takes one with some left for reveals; a 55 m² wall takes two, and at that size one 25 kg tub does the same job. How absorbent the wall is decides where you land in the band — the guide to rendering different substrates helps you judge it before ordering.
15 kg or 25 kg: Which Bucket the Job Needs
| Job | Bucket | Plan on |
|---|---|---|
| One elevation, extension, garage, repair | Cerplast 15kg (this one) | About 43 m² |
| Whole house, terrace run, several elevations | Atlas Cerplast 25 kg | About 71 m² |
Why the smaller bucket makes sense:
- No half-used tub left over — one Cerplast 15kg matches one elevation.
- Same primer, same figures — bond, drying time and working temperature belong to the material, not the pack size.
- Named in a UK system approval — BBA Agrément Certificate 13/5018 lists Cerplast as the key coat in the Atlas EPS and mineral wool insulation systems.
- Ready to use — no water, no mixing ratio; stir and start.
- Easy top-up — Cerplast 15kg finishes a wall when a 25 kg tub falls just short.
Technical Data
| Property | Value |
|---|---|
| Composition | Acrylic resins and quartz flour, ready to use |
| Bond to concrete | At least 1.0 MPa |
| Density | Approx. 1.5 g/cm³ |
| Average consumption | 0.3 kg/m² |
| Drying before rendering | 4 to 6 hours |
| Working temperature | +5 °C to +30 °C |
| Application | Roller, brush or machine |
| Shelf life | 12 months from the date on the bucket |
Which Renders Go Over It
- Technical sheets — Cerplast goes under Atlas thin-coat renders that are mineral, acrylic, silicone and mosaic.
- BBA approval — stricter: in the certified systems, silicone and silicone-silicate finishes take a separate silicone-based key coat. On a certified job, follow the approval.
- From this shelf — Atlas Acrylic Render fits both documents.
The finish-by-finish detail is on the 25 kg tub's page.
Getting the Wall Ready
- Seasoned and dry. New cement and cement-lime plaster: at least 7 days and 4 % moisture or less. Concrete: at least 28 days and below 4 %. Both at +20 °C and 50 % humidity — allow longer in cold, damp weather.
- Even. Fill hollows with ZW 330 after priming the repair with Atlas Uni-Grunt or the NKP primer.
- Clean. Remove dust, dirt, lime, oil, grease, wax and old oil or emulsion paint; treat mould and algae with Mykos Plus first.
- Apply. Stir Cerplast 15kg before and during use, never thin or thicken it, and spread it evenly with a roller, brush or machine. Keep it out of direct sun, wind and rain while it dries.
- Render. Start once it is fully dry, 4 to 6 hours later. Wash tools in clean water; remove dried splashes with Szop 2000.
The full order of work is in the wall preparation method, and roller choice and weather planning in the quartz primer guide for EWI systems.
Colour and Tinting
- White as standard — most jobs use white, because the render on top carries the colour.
- Tinted to order — Renders World tints Atlas products at the counter, to the SAH colour system (400 shades in the 2023 English sheet, 418 in the 2025 Polish one).
- Returns — tinted buckets are mixed for your order and cannot be returned for a change of mind.
Storage and Pauses in the Work
- Shelf life — 12 months from the production date on the bucket.
- Storage — keep buckets frost-free, not in an unheated van or shed over winter.
- End of the season — if the weather closes in before the render can go on, the reinforced basecoat may be left protected by the primer alone until conditions allow the finish.
FAQ — Coverage, Renders and Weather
How many 15 kg buckets does one wall take?
Divide the wall area by 43 m² and round up: 15 kg ÷ 0.35 kg/m² = 42.9 m² per bucket, the top of the BBA key-coat band; at the 0.3 kg/m² average one bucket reaches 50 m².
Can Cerplast 15kg go under silicone render?
The technical sheets say yes. In the BBA certified systems, though, silicone and silicone-silicate finishes take a separate silicone-based key coat, so on a certified job follow the approval. The primer comparison for thin-coat systems shows which primer suits which finish.
What weather does it need?
Mass, wall and air between +5 °C and +30 °C, no direct sun, wind or rain on the primed surface while it dries, and 4 to 6 hours before the render goes on.
Does the BBA approval cover the bucket or the wall?
The wall. Certificate 13/5018 covers the Atlas external wall insulation systems, with Cerplast named as the key coat inside them. Quote it together with the system you are installing.
How long does a bucket keep?
Twelve months from the date printed on the bucket. Store it frost-free over winter; Renders World processes orders the same day when the stock is there.