Description
Atlas One Coat Dash Cover (OCDC) 30 kg is the high-build, polymer-modified mortar that covers existing pebbledash in a single pass — flattening legacy textured facades to a smooth, render-ready surface at 10–15 mm thickness, with approximately 120 minutes of open time and an extended workability that suits both machine spray and manual trowel application. Sold within the professional EPS adhesives and basecoats range at Renders World, OCDC is the specification UK installers reach for when modernising 1950s–1980s pebbledash elevations into contemporary thin-coat silicone or acrylic finishes without the labour cost and dust hazard of hacking off the original dash.
Where Atlas OCDC Performs Best — Pebbledash Modernisation and Legacy Facade Refurb
Atlas OCDC is a thick-section, polymer-modified cementitious mortar engineered to bond directly onto existing pebbledash and form a flat, sound, render-ready receiver layer in one pass — eliminating the traditional sequence of hacking off the dash, repairing the substrate, applying a scratch coat, and waiting for cure before the levelling layer goes on. A 10–15 mm cover passes over the aggregate face, fills between the stones, and presents a flat plane to the next stage of the build within a single working day.
The product belongs on the UK's vast stock of 1950s–1980s pebbledashed semi-detached houses, ex-local-authority terraces, and post-war estates where homeowners and contractors want a modern thin-coat render finish without the upfront cost and disruption of dash removal. It also suits refurbishment elevations where the existing dash is sound but visually dated, where dust-creating mechanical removal is restricted (party walls, conservation streets, occupied properties), and where the project budget rules out a full EWI build-up but allows a render-only modernisation pass.
Why Trade Specifiers Choose Atlas OCDC
- One pass, no removal: Covers existing pebbledash directly at 10–15 mm thickness, skipping the labour-intensive and dust-heavy hacking-off stage that traditional modernisation routes require — the single biggest programme and cost saving on legacy-dash projects.
- Polymer-modified flex: The cured layer flexes with the building rather than cracking rigidly, accommodating the differential movement that legacy facades exhibit between original masonry, the aged dash layer, and the new cover coat.
- 120-minute open time: Roughly two hours of workability lets a crew cover a continuous elevation panel without creating cold joints between fresh and stiffening passes — critical for the visual continuity of the eventual thin-coat finish.
- Machine or hand application: Sprays through standard rotor-stator render machines at production rates for full-elevation runs, or trowels by hand on smaller detailed areas and around openings — one product covers both site formats.
- Slump-resistant heavy build: Stays in place at 15 mm vertical application without sliding off the dash face, thanks to the cohesive mix that grips the textured aggregate surface immediately on contact.
- Render-ready cured surface: Once dry, the cover layer presents a flat, sound, mineral surface that accepts a standard quartz primer and any certified thin-coat decorative render without further levelling work.
Technical Specifications — Atlas OCDC Data Sheet Highlights
| Property | Value |
|---|---|
| Product type | Polymer-modified cementitious cover and levelling mortar |
| Pack size | 30 kg bag |
| Application method | Machine spray or manual trowel |
| Recommended thickness | 10–15 mm (single pass over existing pebbledash) |
| Coverage yield | ≈ 1.2–1.5 m² per 30 kg bag at 10–15 mm |
| Open time | ≈ 120 minutes |
| Application temperature | +5 °C to +25 °C (substrate and ambient) |
| Substrates | Existing pebbledash, sound mineral render, concrete, brick |
| Reinforcement | Fibreglass mesh recommended at full thickness for impact zones and around openings |
| Next-stage receiver | Quartz primer plus certified thin-coat render |
| Shelf life | 12 months, sealed, dry storage |
How to Apply Atlas OCDC — Substrate Prep, Bead Choice, Single-Pass Cover
Start with a thorough substrate inspection — tap-test the existing pebbledash with a hammer handle across the elevation, and remove any drummy, loose, or detached areas before application. Wash the dash face to remove dust, lichen, and loose aggregate, then allow the surface to dry fully before the cover layer goes on. Where existing render or dash has detached over more than a small area, repair locally with a structural mortar and let the patch cure before continuing — covering over a known weak zone simply transfers the failure into the new layer.
Mix the 30 kg bag to the water ratio printed on the pack using a paddle mixer on low speed, or feed it through a continuous-mixing render machine for production-rate spray application. Apply in a single 10–15 mm pass, working from the top of the elevation downward, and rule off with a long darby to establish the flat plane that the next stage will follow. For impact zones and around openings, press a fibreglass mesh into the wet layer at full thickness — the basecoat and mesh reinforcement layer guide covers the overlap discipline that prevents cracking at corners and reveals.
Installation Notes — Conditions, Curing, Next-Stage Receiver
Atlas OCDC cures best between +5 °C and +25 °C, with both substrate and ambient temperatures inside that range for at least 24 hours after application. Direct sunlight and strong wind on a freshly applied 15 mm layer will flash-dry the surface and risk a weakened bond to the dash underneath — schedule the cover pass for overcast conditions or shaded scaffolding wherever the elevation orientation allows.
Once the cover layer is fully cured (typically 3–5 days at 15 mm thickness, longer in cool or humid weather), the surface is ready for the next-stage finish — a coat of a quartz substrate primer equalises the suction across the cover layer, then any certified thin-coat silicone render from the Atlas decorative line completes the modernisation. The visual transformation from pebbledash to a smooth coloured silicone finish is the single biggest perceived value driver on a refurbishment project, and OCDC is the layer that makes it possible without dash removal.
Pro Tips From UK Installers Using Atlas OCDC
- Tap-test the whole elevation first. Drummy or loose pebbledash sounds hollow under a hammer handle — mark these zones with chalk before mixing, repair locally, and only then cover the elevation. A single hollow patch under the new layer becomes the failure point that drags the whole cover off the wall years later.
- Build the corners before the field. Cover the external angles and reveals first with a bead and a manual trowel pass, then spray or trowel the field areas into the established corner thickness — far easier to maintain a true 15 mm plane than to chase one across an already-built field.
- Reinforce the high-traffic zones. A fibreglass mesh embedded into the wet OCDC at ground-floor impact level and around door openings absorbs the knocks and trolley contacts that crack unreinforced thick-section renders within the first decade of service.
- Schedule the primer pass three days out. The cover layer can feel firm in 24–48 hours but still carries residual moisture at depth — waiting three days before priming on 15 mm work prevents the trapped moisture from blooming up through the decorative finish as efflorescence months later.
Is Atlas OCDC Right for Your Project?
- Atlas OCDC is the right call when the elevation carries sound but visually dated pebbledash and the project goal is a modern thin-coat render finish without the cost, dust, and disruption of mechanical dash removal.
- New-build EWI installation? A dash-cover product is overspecified for new-build work — switch to a 2-in-1 adhesive and basecoat such as Atlas Hoter U Grey 25 kg for the bonding and reinforcement layers, then a thin-coat decorative finish over the certified system.
- Pebbledash is failing or detached? Cover-coat products work over sound dash, not over a substrate that has already failed at the bond line — extensive drumming or loose aggregate calls for full removal and a conventional render build-up rather than a single-pass cover.
- For substrate-decision context, the rendering on different substrates guide walks through how cover-coat decisions interact with brick, block, painted, and pebbledashed substrates across UK building stock.
- For full-system specification, plan the modernisation sequence: OCDC cover layer, fibreglass mesh in impact zones (mesh range), three-day cure, quartz primer, and a thin-coat silicone render in the chosen colour. Each stage builds on the previous one — skipping the primer or rushing the cure remains the single most common cause of premature failure on dash-cover modernisation projects.
FAQ — Atlas OCDC Coverage, Compatibility, Ordering
How many bags of OCDC do I need per 100 m² of pebbledash?
At a yield of approximately 1.2–1.5 m² per 30 kg bag at 10–15 mm thickness, a 100 m² elevation consumes around 70–85 bags depending on the depth of the dash texture being filled and the surface evenness across the wall. Order 90 bags per 100 m² as a working benchmark — deeper aggregate, irregular substrates, and the natural waste at edges and openings push real-world consumption above the rated yield on every job.
Can I use OCDC over any pebbledash, or does the original dash have to be in specific condition?
The original dash must be sound, securely bonded to the underlying masonry, and free from drummy or detached areas — the cover layer transfers its weight onto the existing dash, so any pre-existing failure underneath becomes the failure point of the new system. Tap-test the elevation before mixing, repair locally where the dash sounds hollow, and only cover sound substrate. Where failure is widespread, a full removal and conventional render build-up is the correct specification rather than a cover coat.
What finish coats can I apply over a cured OCDC layer?
Once fully cured (3–5 days at 15 mm thickness), the OCDC surface accepts a standard quartz primer followed by any certified thin-coat decorative render — silicone, silicone-silicate, or acrylic finishes all work. Pale modern colours in fine-grain silicone are the most common specification on dash-modernisation projects, since the visual jump from textured pebbledash to a smooth coloured render delivers the strongest perceived value increase on a refurbishment.
Can I apply OCDC by hand, or do I need a render machine?
Both methods are valid — machine spray suits production runs across continuous elevations where the 30 kg bag size and pumpable mix design pay back the setup time, while hand trowel application works for smaller modernisation projects, detailed areas, and corners where machine spray is awkward. Most installers combine both on the same job: machine spray the field areas and hand-trowel the corners and reveals into the established thickness.
Can I apply OCDC during cold months?
Application requires substrate and ambient temperatures of at least +5 °C and ideally well above freezing through the first 24 hours of cure — the polymer modifications and cement hydration both need stable above-freezing conditions to develop full strength. In genuinely cold periods (October to March in much of the UK), check the 24-hour forecast before the cover pass, and avoid applying late in the day where overnight temperatures may drop below the application range.
What does an OCDC-based modernisation typically last before maintenance?
A correctly specified OCDC cover layer, primer, and thin-coat decorative render system on a sound pebbledash substrate typically delivers 15–20 years of weather-tight service before the decorative coat needs refreshing — comparable to a new-build thin-coat installation and substantially longer than a paint-only refurbishment over the original dash. The cover layer itself, protected under the primer and finish, can be expected to remain serviceable for the full design life of the renewed facade.
Technical Documentation — Atlas OCDC TDS