Repair Systems — 03 — Facade & External Envelope
Two-coat sand-cement render systems
Technical product reference for two-coat sand-cement render systems used in render repair, removal and reinstallation works on Australian masonry and heritage facades. Covers product classification, system selection, application requirements, and brand comparisons.
What are two-coat sand-cement render systems?
Two-coat sand-cement render is the traditional facade render system used in Australian construction prior to the widespread adoption of polymer-modified pre-bagged products. The system consists of a scratch coat (or base coat) and a finish coat, both composed of Portland cement and well-graded render sand mixed in specified proportions. Unlike polymer-modified systems, sand-cement render does not incorporate SBR latex, acrylic, or other polymer admixtures as part of the standard mix — though admixtures may be added where specified for improved adhesion or durability.
Product Reference
3 products — 3 brands — two-coat sand-cement render systems — scroll to view all
Mapei Planitop XS (sand-cement system)
Two-coat sand-cement cementitious render — exterior facade
System Description
Traditional two-coat sand-cement render using site-batched or pre-bagged sand-cement as the primary binder. The scratch coat is a 1:4 cement:sand mix applied at 10–15mm and scratched to provide a key. The finish coat is a fine sand-cement mix applied at 6–10mm and finished by float or steel trowel. Mapei Planitop XS can be used as the base coat in a sand-cement render system where a cementitious binder without polymer admixture is required. Confirm with Mapei Australia whether Planitop XS is suitable as a traditional sand-cement type base coat without additional polymer, and confirm site-batched versus pre-bagged approach with the project specification. TODO: owner confirm — verify sand-cement system specification and suitable Mapei products with Mapei Australia technical before specifying.
Technical Properties
- Scratch coat — 1:4 cement:sand mix at 10–15mm
- Finish coat — fine sand-cement at 6–10mm
- No polymer admixture (unless separately specified)
Limitations
- More susceptible to shrinkage cracking than polymer-modified systems — control joint spacing critical
- Lower adhesion than polymer-modified systems on smooth substrates — substrate preparation critical
- Not recommended for fine cracking repair without mesh reinforcement
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
System Description
Traditional site-batched two-coat sand-cement render using Boral OPC (Ordinary Portland Cement) and locally sourced washed render sand. The scratch coat is typically a 1:3 or 1:4 cement:sand mix applied at 10–15mm to provide a strong base and key for the finish coat. The finish coat is a finer 1:4 or 1:5 mix for a smooth or textured finish. Site-batched render allows the mix ratio, aggregate size, and admixture selection to be adjusted to suit specific substrate conditions and environmental exposure. Boral OPC is widely available nationally. Confirm all mix ratios, admixture requirements, and inter-coat timing with the project specification. In coastal environments, confirm admixture requirements to reduce chloride ingress susceptibility. TODO: owner confirm — confirm mix design, admixtures, and coastal suitability with project engineer before specifying.
Technical Properties
- Site-batched — mix ratios adjusted to suit project requirements and specification
- Scratch coat 1:3–1:4 cement:sand at 10–15mm
- Finish coat 1:4–1:5 at 6–10mm
Limitations
- More susceptible to shrinkage cracking than polymer-modified systems — control joint spacing is critical
- Site-batched quality depends on mixing accuracy — pre-bagged alternatives offer more consistent results
- Not recommended for substrates requiring high adhesion (polished concrete, existing paint — prime first)
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Rockcote Pre-Mix Render Base + Rockcote Fine Render
Pre-bagged two-coat sand-cement type render — exterior facade
System Description
Rockcote (Saint-Gobain Weber Australia) produces a range of pre-bagged render products for exterior masonry. A sand-cement type render system can be specified using Rockcote pre-bagged products where a lower polymer content or traditional sand-cement appearance is preferred. Confirm the specific Rockcote product suitable for a sand-cement type specification with Saint-Gobain Weber Australia technical — the Rockcote range includes both polymer-modified and sand-cement base render products. Rockcote products are widely available through Saint-Gobain Weber trade distribution nationally. TODO: owner confirm — confirm the specific Rockcote product for sand-cement type render specification with Saint-Gobain Weber / Rockcote technical before specifying.
Technical Properties
- Pre-bagged — consistent mix quality compared to site-batched
- Suitable for exterior masonry facades
- Rockcote range widely available through Saint-Gobain Weber trade distribution
Limitations
- TODO: owner confirm — confirm specific Rockcote product for sand-cement type render specification with Saint-Gobain Weber/Rockcote Australia
- Rockcote range is broad — confirm with technical that the selected product is sand-cement type rather than polymer-modified
- Confirm coastal suitability — standard sand-cement type render may not be suitable in marine environments without admixture
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
System Comparison
Side-by-side comparison of two-coat sand-cement render systems. Confirm all product selections against the current manufacturer TDS before specifying.
| Product system | Brand | Coat system | Binder | Application | Coastal suitable | Heritage | Primary use |
|---|---|---|---|---|---|---|---|
| Planitop XS (sand-cement system) | Mapei | Two-coat | Sand-cement (confirm with Mapei) | Hand trowel / float | Confirm with Mapei technical | Confirm suitability | Exterior masonry and concrete facades where sand-cement is specified |
| Boral OPC + Render Sand | Boral | Two-coat site-batched | OPC + washed render sand | Hand trowel / float | Admixture required — confirm | Compatible with heritage masonry | Site-batched render on brick and masonry facades |
| Rockcote Pre-Mix Render Base + Fine Render | Rockcote / Saint-Gobain Weber | Two-coat pre-bagged | Sand-cement type (confirm with Rockcote) | Hand trowel / float | Confirm with Rockcote technical | Heritage use confirmed with technical | Pre-bagged sand-cement type render on exterior masonry |
Do not confuse two-coat sand-cement render with:
- Polymer-modified render (has admixtures) — systems where SBR latex, acrylic, or vinyl-acetate polymer dispersions are incorporated into the mix to improve adhesion, flexibility, and durability — listed on the two-coat polymer-modified render page
- Fibre-reinforced render (fibres added) — systems where polypropylene or glass fibres are incorporated into the render mix to provide enhanced tensile resistance — listed on the fibre-reinforced render page
- EIFS (insulation board) — systems incorporating a layer of expanded polystyrene (EPS) insulation board with render applied over fibreglass mesh — listed on the EIFS render systems page
- Acrylic spray-applied render (factory-blended acrylic) — pre-bagged acrylic/cement renders applied by machine spray — listed on the acrylic spray-applied render page
- Structural repair mortars (Fosroc Renderoc, Sika MonoTop — different class) — polymer-modified cementitious mortars formulated specifically for concrete repair (spalling, delamination, carbonation) — 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.