Repair Systems — 03 — Facade & External Envelope
Polymer-modified render systems — two-coat
Polymer-modified cementitious render systems are the preferred specification for full render replacement on Class 2 strata facades, providing superior bond strength to existing substrates, reduced shrinkage cracking and extended service life compared to traditional sand cement render.
Polymer-modified render installation systems
Polymer-modified two-coat render systems are the preferred render specification for full removal and replacement of failed render on Class 2 strata concrete and masonry facades. The incorporation of acrylic polymer into the cementitious render matrix improves adhesion to substrates, reduces shrinkage cracking, and increases water resistance — all critical performance improvements for render on multi-storey facade elements subject to weathering, thermal cycling, and ongoing maintenance access constraints.
Product Reference
3 products — 3 brands — Sika / Mapei / Fosroc
System Description
SikaRenderEM is Sika Australia's polymer-modified render for full-replacement two-coat render installation on concrete and masonry facades. Applied in a scratch coat (8–12mm) followed by a finish coat (6–8mm), it provides improved adhesion, reduced shrinkage cracking, and better water resistance than traditional sand/cement renders. The pre-bagged format provides consistent polymer content and eliminates site batching variability. In Class 2 strata render removal and replacement programmes, SikaRenderEM is specified by remedial contractors who work within the Sika supply ecosystem and require a documented, engineered render system with TDS backing for defect liability purposes. The integrated Sika system — SikaCem bonding slurry, SikaRenderEM scratch and finish coats — provides full manufacturer compatibility across the render build. Confirm current product names, application sequence, and bonding agent requirements with Sika Australia before specifying.
Technical Properties
- Polymer-modified acrylic — improved adhesion, water resistance, and crack resistance over OPC renders
- Pre-bagged powder — consistent factory-controlled polymer content
- Scratch coat 8–12mm + finish coat 6–8mm — total 14–20mm system
Limitations
- Requires SikaCem bonding slurry on dense or smooth concrete substrates
- Do not exceed maximum coat thickness per coat — risk of sag and cracking
- Confirm current product name with Sika Australia before ordering
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Mapei Planitop XS / Planitop Smooth
Polymer-modified render installation mortar
System Description
Mapei Planitop XS is a polymer-modified, fibre-reinforced repair mortar used for full render installation in Class 2 strata facade work. Its wide application thickness range (5–30mm) makes it suitable for both the base/scratch coat and as a finish coat when applied at reduced thickness. The fibre reinforcement provides improved plastic shrinkage cracking resistance compared to non-reinforced polymer renders. In Australian strata render installation work, the Mapei system uses Planitop XS for the base coat and Planitop Smooth & Repair for the fine finish coat, with Planicrete bonding slurry on dense concrete substrates. The Mapei approach is widely used by remedial contractors who prefer the Mapei product range and the technical support from Mapei Australia. Confirm current product names and system specification with Mapei Australia before ordering.
Technical Properties
- Wide thickness range 5–30mm — suits variable substrate profile in full render replacement
- Fibre-reinforced — reduced plastic shrinkage cracking during cure
- Polymer-modified acrylic — improved adhesion and water resistance
Limitations
- Maximum 30mm per coat — multiple coats required for deeper substrate defects
- Requires bonding agent on dense or painted substrates
- Confirm current product name with Mapei Australia before ordering
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Fosroc Renderoc Classic / Renderoc FC
Polymer-modified render installation system
System Description
Fosroc Renderoc Classic is the scratch coat and Renderoc FC is the fine finish coat in the Fosroc render installation system. Both are polymer-modified, pre-bagged products that provide improved performance over site-batched OPC renders. The Fosroc system integrates with Nitobond AR bonding agent for dense concrete substrates, and is widely used by contractors working in the Fosroc supply ecosystem on both strata and commercial facade remediation projects. In Australian Class 2 strata render removal and replacement, the Fosroc Renderoc system is specified where project QA requires a documented engineered render system with TDS-backed specifications. The Renderoc range is positioned as a step above generic polymer-modified renders, with product support from Fosroc Australia's technical team. Confirm current product names and Renderoc grade suitability with Fosroc Australia before specifying.
Technical Properties
- Renderoc Classic: scratch/base coat 8–15mm; Renderoc FC: finish coat 3–6mm
- Polymer-modified — improved adhesion and crack resistance
- Compatible with Fosroc Nitobond AR bonding agent system
Limitations
- Requires Nitobond AR on dense, low-absorption substrates
- Confirm current Renderoc product name with Fosroc Australia — multiple grades in range
- Do not exceed maximum coat thickness per TDS
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Polymer-modified render installation comparison
All systems require bonding agent on dense substrates. Confirm current product names with manufacturers.
| Product | Brand | Scratch coat | Finish coat | Fibre | Key feature |
|---|---|---|---|---|---|
| SikaRenderEM | Sika | 8–12mm | 6–8mm | Optional variant | Integrated Sika facade system |
| Planitop XS / Smooth | Mapei | 5–30mm | 2–6mm Smooth | Yes — included | Wide thickness range — fibre-reinforced |
| Renderoc Classic / FC | Fosroc | 8–15mm | 3–6mm FC | No (confirm variant) | Documented Fosroc system with Nitobond |
Disclaimer
General technical information only. Render system selection must be confirmed against substrate type, existing render system, and the current manufacturer TDS. Confirm compliance with AS 3700. Not a substitute for professional advice.