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, application requirements, and brand comparisons.
What are two-coat polymer-modified render systems?
Two-coat polymer-modified render systems consist of a cement-based base/scratch coat and a finer finish coat, both incorporating polymer admixtures (acrylic, SBR, or vinyl-acetate polymer dispersions) to improve adhesion, flexibility, and durability compared to traditional sand-cement mixes. They are applied in sequence — a thicker scratch coat first to establish level and key, followed by a finer finish coat once the base coat has achieved initial set.
Product Reference
4 products — 4 brands — two-coat polymer-modified render systems — scroll to view all
Mapei Planitop XS + Planitop Smooth & Repair
Two-coat polymer-modified cementitious render system
System Description
The Mapei two-coat polymer-modified render system pairs Planitop XS as the base/scratch coat with Planitop Smooth & Repair as the fine finishing coat. Planitop XS is a polymer-modified, lightweight, cementitious repair mortar suitable for application as a scratch coat or base render on concrete, masonry, and block substrates in both interior and exterior environments. It has good adhesion to prepared substrates without the need for a separate bonding slurry in most applications — confirm primer requirement with Mapei Australia for specific substrates. The finish coat, Planitop Smooth & Repair, is a fine-textured polymer-modified mortar that provides a smooth working surface ready for coating or paint. The combined system is widely used for facade patch repair, render cracking remediation, and full-sheet re-render on Class 2 strata buildings. Both products are pre-bagged and mixed with clean water only on site — no separate polymer additive is required. Application is by steel trowel for scratch coat and stainless steel or plastic float for finish coat. A minimum of 24 hours between scratch coat and finish coat application should be allowed. Confirm current TDS, DFT requirements, and primer specification with Mapei Australia technical before specifying.
Technical Properties
- Two-coat system — Planitop XS (base/scratch) + Planitop Smooth & Repair (finish) — both pre-bagged
- Polymer-modified cementitious binder — good adhesion to concrete, masonry, and block substrates
- Exterior and interior use — balcony soffits, facade walls, stair risers, masonry blockwork
Limitations
- Confirm primer requirement for each substrate type with Mapei Australia — Planitop XS has good inherent adhesion but substrate condition affects bonding performance
- Minimum inter-coat time between base and finish coats must be confirmed from current TDS — avoid applying finish over a still-green scratch coat
- Not suitable for structural crack repair where active cracking requires flexible bridging — use a crack-bridging coating system over the cured render instead
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Rockcote Primus Basecoat + Rockcote Finessa
Two-coat polymer-modified render system — exterior facade
System Description
Rockcote's standard exterior two-coat render system pairs the Primus Basecoat as the polymer-modified base/scratch coat with the Finessa Fine Render as the smooth finishing coat. Rockcote Primus Basecoat is a pre-blended polymer-modified cement render designed for machine or hand application as a full-thickness base coat over masonry, AAC, concrete, and render substrates. It provides good adhesion and a keyed surface for the finish coat. Rockcote Finessa is a fine-textured, smooth polymer-modified finish render that can be applied directly over the Primus Basecoat to produce a fine render surface ready for coating, painting, or texture finish application. The Rockcote system is widely used in Australian residential and strata remediation projects and is a well-established product range across the eastern seaboard trade supply market. Rockcote products are available through Saint-Gobain trade distribution nationally. The Finessa Fine Render can also be overcoated directly with Rockcote or Dulux Acratex texture coating systems. Confirm all TDS, application rates, inter-coat timing, and primer recommendations with Rockcote technical or Saint-Gobain Weber Australia before specifying.
Technical Properties
- Primus Basecoat — polymer-modified pre-blended render base coat — machine or hand application — suitable over masonry, AAC, concrete, and existing render
- Finessa Fine Render — polymer-modified smooth fine finish coat — applied over Primus Basecoat by steel float or machine
- Exterior and facade system — designed for Australian exterior conditions including coastal and high-UV environments (confirm coastal rating with Rockcote)
Limitations
- Confirm current product names — Rockcote range has been consolidated with Saint-Gobain Weber Australia — some product names may have changed
- Not a structural repair mortar — substrate must be sound before applying render — use a structural repair system where spalling, delamination, or carbonation is present before applying render
- Confirm primer requirement for smooth or non-absorbent substrates (e.g. existing paint, polished concrete) — Primus Basecoat is not self-priming on all substrates
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Sika SikaTop-122 Plus (Scratch) + SikaTop-144 Fine Mortar (Finish)
Two-coat polymer-modified cementitious render system — Sika Australia
System Description
Sika Australia's two-coat polymer-modified render system pairs SikaTop-122 Plus as the polymer-modified scratch/base coat with SikaTop-144 Fine Mortar as the finishing coat. SikaTop-122 Plus is a two-component polymer-modified cementitious mortar used as a scratch coat, bonding layer, and base render for concrete and masonry substrates. It has a thixotropic consistency well suited to vertical facade surfaces without sagging. Applied at 3–10mm thickness per coat, it provides a keyed surface for a fine finishing render or direct tile bond application. SikaTop-144 Fine Mortar (confirm current Australian product name and availability with Sika Australia technical — this product designation may vary from the current Australian catalogue) is applied over the cured SikaTop-122 Plus base coat to provide a smooth, fine-textured finish ready for painting or texture coating. Note: Sika's render product range for Australian facade applications includes the SikaTop series for general repair render — confirm the current designation for the fine finishing render product with Sika Australia technical before specifying. Do not use product TDS data from Sika international catalogues for Australian projects — confirm from the current Sika Australia TDS.
Technical Properties
- SikaTop-122 Plus — two-component polymer-modified cementitious base/scratch coat — thixotropic — suitable for vertical and overhead concrete and masonry surfaces
- Application thickness: 3–10mm per coat — multiple coats can be built up for thicker sections — confirm from current TDS
- SikaTop-144 Fine Mortar — polymer-modified fine finishing coat applied over cured SikaTop-122 Plus base coat
Limitations
- TODO: owner confirm — SikaTop-144 Fine Mortar product name and availability in Australian market — confirm current designation with Sika Australia technical before specifying
- SikaTop-122 Plus is a two-component product — must be mixed with the polymer liquid component, not water alone — confirm mixing ratio and pot life from current TDS
- Not a structural crack repair system — active cracks must be treated separately before applying render system
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Fosroc Renderoc Classic + Renderoc FC
Two-coat polymer-modified render system — Fosroc / Parchem Australia
System Description
The Fosroc two-coat render system pairs Renderoc Classic as the polymer-modified base and scratch coat with Renderoc FC as the fine finish coat. Renderoc Classic is a pre-bagged, polymer-modified, dry-mix render mortar used for render patch repairs and base coat application on concrete and masonry facades. It has excellent adhesion to prepared concrete and masonry substrates and is formulated to accommodate normal facade thermal movement without cracking. Renderoc FC (Fine Concrete) is a fine-textured, polymer-modified, cementitious mortar used as the finish coat, providing a smooth surface texture ready for overcoating with an exterior paint or texture coating system. The Renderoc system is a well-established specification in Australian commercial and strata building remediation, particularly for concrete facade work. Both products are distributed nationally through Parchem Construction Supplies (DuluxGroup), which provides technical support in most metropolitan and regional centres. Confirm current TDS, primer requirements (Nitobond AR bonding slurry is typically used as a primer coat before Renderoc Classic on smooth concrete), and inter-coat timing with Parchem before specifying.
Technical Properties
- Renderoc Classic — pre-bagged polymer-modified render mortar — scratch/base coat for concrete and masonry facade render systems
- Renderoc FC — fine polymer-modified cementitious finish coat — applied over cured Renderoc Classic base coat
- Excellent adhesion to prepared concrete and masonry substrates — Nitobond AR bonding primer/slurry used on smooth or low-absorption surfaces (confirm current specification with Parchem)
Limitations
- Nitobond AR bonding slurry primer is typically required on smooth or dense concrete substrates before Renderoc Classic application — confirm current primer specification with Parchem before specifying
- Not a trafficable exposed system — must be overcoated with a compatible exterior coating or texture system
- Not suitable for application over active cracks — active cracks must be repaired and stabilised before applying render system
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Dulux Acratex RenderWall
Polymer-modified cementitious render — exterior masonry and concrete
System Description
Dulux Acratex RenderWall is a polymer-modified cementitious render for exterior masonry, concrete block, and brick facade surfaces. It is used in two-coat render systems on remedial projects requiring full render removal and replacement or render re-coat over prepared substrates. RenderWall is part of the Dulux Acratex facade system range and is designed to work with compatible Acratex primers, base coats, and finish coats. Confirm current product technical data sheet, system design, coat thicknesses, coverage, and primer specification with Dulux Acratex technical before specifying.
Technical Properties
- Polymer-modified cementitious render — suitable for exterior masonry, concrete block, and brick
- Designed for use within the Dulux Acratex facade system — confirm compatible primer and topcoat from current Acratex TDS
- Confirm coat thicknesses, coverage, and system design from current Dulux Acratex RenderWall TDS
Limitations
- Confirm current product formulation and system design with Dulux Acratex technical before specifying
- Not suitable for application over substrates with active cracking or rising damp — address substrate defects before applying render
- Confirm compatibility with existing substrate treatments and subsequent topcoat systems with Dulux Acratex before specifying
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Rockcote Quick Render
Fast-setting polymer-modified render — masonry and concrete block
System Description
Rockcote Quick Render is a fast-setting polymer-modified cementitious render for masonry and concrete block facade surfaces. Fast-setting renders are useful in remedial projects where rapid return to service is required, or where cold temperatures or tight program schedules necessitate shorter overcoat times. Rockcote Quick Render is part of the Rockcote render system range. Confirm current product technical data sheet, set time, working time, coat thicknesses, coverage, and compatible primer and topcoat specification with Rockcote technical before specifying.
Technical Properties
- Fast-setting polymer-modified cementitious render — suitable for masonry and concrete block exterior surfaces
- Designed for use within the Rockcote facade system — confirm compatible primer and topcoat from current Rockcote TDS
- Confirm set time, working time, coat thicknesses, and system design from current Rockcote Quick Render TDS
Limitations
- Confirm current product formulation and system design with Rockcote technical before specifying
- Fast set time reduces working window — confirm workability window for site conditions before use
- Not suitable for application over substrates with active cracking or rising damp — address substrate defects before applying render
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
System Comparison
Side-by-side comparison of two-coat polymer-modified render systems. Confirm all product selections against the current manufacturer TDS before specifying.
| Product system | Brand | Base coat | Finish coat | Polymer type | Min DFT | Application | Coastal rated | Primary use |
|---|---|---|---|---|---|---|---|---|
| Planitop XS + Smooth & Repair | Mapei | Planitop XS | Planitop Smooth & Repair | Acrylic polymer dispersion | Confirm with Mapei TDS | Trowel / float — machine possible (confirm) | Confirm with Mapei | Facade render repair and re-render — concrete and masonry |
| Primus Basecoat + Finessa | Rockcote / Saint-Gobain | Rockcote Primus Basecoat | Rockcote Finessa Fine Render | Polymer-modified cement | Confirm with Rockcote TDS | Trowel / machine render pump | Confirm coastal rating with Rockcote | Exterior facade render — masonry, AAC, concrete |
| SikaTop-122 Plus + SikaTop-144 | Sika | SikaTop-122 Plus | SikaTop-144 Fine (TODO: confirm AU name) | Polymer-modified — two-component (base) | 3–10mm per coat — confirm from TDS | Trowel — thixotropic | Confirm with Sika AU | Concrete and masonry facade render — exterior and interior |
| Renderoc Classic + Renderoc FC | Fosroc / Parchem | Fosroc Renderoc Classic | Fosroc Renderoc FC | Polymer-modified — pre-bagged | Confirm with Parchem TDS | Trowel / float | Confirm with Parchem | Concrete facade render repair and re-render — commercial and strata |
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.