Two-coat polymer-modified render systems

Sika's polymer-modified two-coat render system for facade repair on concrete and masonry substrates uses SikaRenderEM as the base/scratch coat and a compatible Sika finish render as the float coat. SikaRenderEM is a pre-bagged, polymer-modified cementitious render that incorporates acrylic polymer powder to improve adhesion, flexibility, and water resistance compared to traditional sand/cement mixes. The polymer content reduces cracking tendency and improves compatibility with existing painted or previously rendered substrates where bonding conditions are challenging. In Australian Class 2 strata facade remediation, the two-coat polymer-modified render system is specified where existing render has delaminated, cracked, or is structurally unsound — replacing the render back to the substrate and reinstating a sound, crack-resistant render profile. The scratch coat (8–12mm) is applied and combed to provide a mechanical key, allowed to partially cure, then the finish coat (6–8mm) is applied to achieve the required profile and texture. For applications over existing render patches or where the substrate is dense concrete, a bonding primer (such as SikaBond or SikaCem Slurry) may be required to achieve adequate bond. Confirm current product names, mix ratios, primer compatibility, and maximum application thickness per coat with Sika Australia before specifying.

Mapei's polymer-modified render system for facade repair uses Planitop XS (a polymer-modified, fibre-reinforced repair mortar) as the base layer and Planitop Smooth & Repair as a fine-finish skim or topping coat. The Planitop range is designed for concrete repair and render reinstatement on facades, with the acrylic polymer component providing improved adhesion, reduced shrinkage cracking, and water resistance compared to plain sand/cement mortars. In Australian Class 2 strata render remediation, the Mapei Planitop system is used by contractors working within the Mapei supply ecosystem. The polymer-modified chemistry allows application to previously painted or sealed surfaces (with appropriate primer) and provides a base that resists the salt and moisture cycling common in coastal strata buildings. Planitop XS can be applied at 5–30mm depth, making it suitable for both thin patch repairs and full render coat replacement. Confirm current product names, application thickness, and primer requirements with Mapei Australia before specifying.

Fosroc's Renderoc range provides polymer-modified render mortars for facade repair and reinstatement. Renderoc Classic is a one-component, polymer-modified, cementitious render mortar suitable for rendering over concrete and masonry substrates as part of a two-coat system, while Renderoc FC (fine coat) is used as a finish render coat over the base Renderoc scratch coat. The acrylic polymer modification improves adhesion over existing dense or painted substrates (with appropriate bonding agent) and provides better crack resistance and water resistance than plain sand/cement mixes. In Australian Class 2 strata remediation, the Fosroc Renderoc system is used by remedial contractors who have an established Fosroc supply relationship. The system is particularly valued in commercial and higher-grade strata projects where a documented, engineered render system with consistent product specifications is required for project QA and defect liability purposes. The Renderoc range also integrates with Fosroc Nitobond bonding agents and Conbextra grouting products used in the broader repair specification. Confirm current product names, system specification (scratch + finish coats), and primer compatibility with Fosroc Australia before specifying.