Repair Systems — 03 — Facade & External Envelope
Two-coat polymer-modified render systems
Technical product reference for two-coat polymer-modified cementitious render systems used in full render removal and replacement, render repair, and facade re-render works on Australian Class 2 strata and commercial buildings. Covers product classification, system selection, substrate requirements, application sequence, coat thicknesses, standards compliance, and brand comparisons for specifying engineers and building consultants.
What are two-coat polymer-modified render systems?
Two-coat polymer-modified render systems consist of a cement-based scratch/base coat and a finer finish coat, both incorporating polymer admixtures — typically acrylic, SBR (styrene-butadiene rubber), or vinyl-acetate polymer dispersions — to improve adhesion, flexibility, impact resistance, and durability compared to traditional sand-cement mixes. They are applied in sequence: a thicker scratch coat first (typically 8–15 mm) to establish level, fill substrate irregularities, and create a mechanical key, followed by a finer finish coat (typically 3–6 mm) once the base coat has reached initial set (minimum 24 hours — confirm from TDS).
In remedial building on Australian Class 2 strata, two-coat PM render systems are the standard specification for full render removal and replacement on concrete, masonry, clay brick, and AAC (autoclaved aerated concrete) substrates. They are also used for large-area patch rendering where isolated panels of failed render are removed and the substrate is re-rendered to match the existing profile before painting or texture coating.
Key selection criteria include: polymer type and content, bond strength to the specific substrate, shrinkage characteristics, minimum and maximum coat thicknesses, inter-coat timing, compatibility with the proposed topcoat or texture system, resistance to coastal salt exposure, and whether a bonding primer or slurry coat is required before the scratch coat.
Product Reference
Genuine current Australian two-coat render systems — one card per row, two per row on desktop, all visible (no carousel). Each card: Key Properties · Performance Highlights · Cautions · Key Warnings · Advanced Technical Data.
Dulux Acratex RenderWall — Acrabuild base + Acratex texture finish
Acrylic polymer-modified cement render — two-coat Acratex facade system
Rockcote Quick Render PM100 + Quick Render Fine
Polymer-modified cement render — base + fine finish, over Keycote
Confirm data against current TDS.
Mapei Nivoplan — levelling render mortar (+ Mapei finish coat)
Cement-based levelling render — EN 998-1 GP, category CS IV
Confirm data against current TDS.
Sto Render System — StoLevell base + Sto finishing render
Mesh-reinforced mineral/cement base render + Sto facade finish
Confirm data against current TDS.
Boral Uni-Render
Polymer-modified cement render — base render for masonry & concrete
Confirm data against current TDS.
System Comparison
Side-by-side comparison of two-coat polymer-modified render systems — confirm all product selections against the current manufacturer TDS before specifying.
Scroll the table sideways to see every column →
| Product system | Brand | Base coat | Finish coat | Polymer type | Base coat thickness | Finish coat thickness | Machine applicable | Bonding primer required | Coastal rated | Primary use |
|---|---|---|---|---|---|---|---|---|---|---|
| Acratex RenderWall (Acrabuild) | Dulux Acratex | Acrabuild base render | Acratex acrylic texture | Acrylic polymer-modified | 3–4 mm skim; up to 12 mm multi-pass | Confirm Acratex finish TDS | Yes — trowel or pump | Confirm sealer per substrate | Confirm with Dulux | Levelling render + texture on brick/block (NSW & QLD) |
| Quick Render PM100 + Fine | Rockcote / Saint-Gobain | Quick Render PM100 | Quick Render Fine | Polymer-modified cement | ≈10 mm/coat (HB 5–30 mm) | Confirm with Rockcote TDS | Yes — hand or machine | Keycote on smooth substrates | Confirm with Rockcote | Render over masonry, concrete, EPS/XPS |
| Nivoplan (+ Mapei finish) | Mapei | Nivoplan levelling render | Confirm Mapei finish coat | Cement + synthetic resin (GP) | 2–20 mm per application | Confirm with Mapei AU | Yes — trowel or machine | Confirm primer | Confirm with Mapei AU | Levelling render int/ext — confirm AU availability |
| Sto Render System | Sto Australia | StoLevell base (mesh) | Sto finish (e.g. Stolit) | Mineral/cement, mesh-reinforced | Confirm with Sto TDS | Confirm with Sto TDS | Confirm with Sto | Confirm bonding/primer | Confirm with Sto | Reinforced render — masonry, concrete, AAC |
| Uni-Render | Boral | Uni-Render base | Confirm finish/texture | Polymer-modified cement | Confirm with Boral PDS | Confirm with Boral PDS | Yes — trowel or pump | Confirm primer | Confirm with Boral | Render over masonry and concrete |
Do not confuse two-coat polymer-modified render with:
- Fibre-reinforced render systems — systems where polypropylene or glass fibres are incorporated into the render mix to provide enhanced tensile resistance and crack distribution — listed on the fibre-reinforced render page
- EIFS (External Insulation and Finish Systems) — systems incorporating a layer of expanded polystyrene (EPS) insulation board mechanically fixed or adhesively bonded to the substrate with render applied over fibreglass mesh — listed on the EIFS render systems page
- Acrylic spray-applied render — factory-blended acrylic/cement renders applied by machine spray, typically to AAC or lightweight construction substrates — listed on the acrylic spray-applied render page
- Salt-resistant renovating render — systems specifically formulated with reduced portland cement content and specialist polymer admixtures to resist chloride and sulfate attack in coastal and salt-affected environments — listed on the salt-resistant render page
- Elastomeric crack-bridging coatings — applied over cured render as a topcoat to bridge hairline movement cracks — not render systems — listed under external coating and paint deterioration
- Structural repair mortars — polymer-modified cementitious mortars formulated specifically for concrete repair (spalling, delamination, carbonation) — such as ARDEX WPM series, Sika MonoTop, Fosroc Renderoc HS — different product class from render systems
Disclaimer
This page provides general technical information only. Final product selection must be confirmed against the current manufacturer technical data sheet, project specification, substrate condition, exposure classification, AS 3700, NCC requirements, and applicator warranty conditions. Products marked TODO: owner confirm require verification before specifying. Do not rely on this reference as a substitute for professional engineering or facade consultant advice.