Repair Systems — Rising Damp
Renovating salt-resistant plaster systems
Technical product reference for WTA 2-9-04 compliant renovation plaster systems for replastering masonry walls after chemical DPC injection — covering salt tolerance, pore structure, brand comparisons and system selection.
What are renovating salt-resistant plaster systems?
Renovating salt-resistant plaster systems (also called WTA renovation plasters) are specialist replastering products designed for masonry walls drying out after rising damp treatment. They differ fundamentally from standard plasters in their pore structure — WTA renovation plasters are formulated with an enlarged pore matrix that accommodates salt crystallisation within the plaster body without surface spalling or failure.
When a wall has been subject to rising damp over many years, the masonry and existing plaster become loaded with hygroscopic salts — primarily nitrates, chlorides and sulphates leached from the ground. Even after DPC injection stops further capillary rise, these salts remain in the wall fabric and continue to crystallise as the wall dries. Standard gypsum or Portland cement plasters cannot tolerate this salt environment and will fail rapidly through spalling, blistering and loss of adhesion.
The WTA 2-9-04 renovation plaster standard defines the minimum pore volume, mechanical properties and salt tolerance required. Remmers SP renovation plasters are the most established WTA-compliant products in Australia, used as the follow-on plastering system after Remmers Kiesol or Kiesol C DPC injection.
Do not confuse with:
- Standard gypsum plaster or cement render — not salt-resistant — will fail on rising damp walls
- Crystalline waterproofing slurries (Xypex, Vandex Super) — active waterproofing against hydrostatic pressure — not a renovation plaster
- Breathable renders (NHL lime, silicate render) — for exterior application — different product category
- Waterproof cementitious coatings — a surface barrier coating — not the same as a salt-tolerant renovation plaster with enlarged pore structure
Product Reference
3 products — 3 brands — WTA renovation plasters and salt-resistant render systems for rising damp remediation
System Description
The Remmers SP Renovation Plaster System is a WTA 2-9-04 compliant two-coat renovation plastering system designed for replastering masonry walls after chemical DPC injection or in areas affected by rising damp and salt contamination. The system comprises SP I (renovation undercoat) and SP II (renovation finish plaster) — both formulated to tolerate the high levels of hygroscopic salts (nitrates, chlorides, sulphates) present in masonry walls drying out after rising damp treatment. WTA renovation plasters work by providing an enlarged pore structure within the plaster body — creating a reservoir volume within the plaster matrix that accommodates salt crystallisation without surface spalling or cracking. The plaster remains vapour-permeable (breathable), allowing the wall to continue drying while the salts crystallise harmlessly within the plaster body rather than at the surface. Standard gypsum or Portland cement plasters do not have this pore structure and will fail rapidly when applied to rising damp walls. Remmers is the most established WTA renovation plaster supplier in Australia. Confirm current SP product names, the full system sequence (including pre-spray if required), and technical support availability with Remmers Australia before specifying on a project.
Technical Properties
- WTA 2-9-04 compliant — renovating plaster standard — enlarged pore structure accommodates salt crystallisation without surface failure
- Vapour-permeable (breathable) — wall continues to dry through the plaster layer during the drying-out period
- High salt tolerance — formulated to resist hygroscopic salts including nitrates, chlorides and sulphates present in rising damp walls
Limitations
- WTA renovation plaster must not be applied until after chemical DPC injection has been completed and the injection product has cured
- Old plaster must be stripped to a minimum of 300mm above the visible salt tide mark before applying renovation plaster — salt damage in the substrate extends beyond the visible stain
- Gypsum-containing backgrounds and gypsum undercoats are not compatible — remove all existing gypsum plaster before applying renovation plaster
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Mapei Mape-Antique Renovation Plaster System
Salt-resistant renovation plaster system
System Description
Mapei's Mape-Antique renovation plaster range provides salt-resistant renovation plastering products for replastering masonry walls in rising damp remediation. The Mape-Antique range is specifically formulated for restoration and remediation of historic and existing masonry buildings, offering salt tolerance and vapour permeability suited to the drying-out phase after DPC treatment. Mapei's national distribution network across Australia means that Mape-Antique renovation plaster products are accessible through Mapei trade supply channels in most Australian states. For strata building managers and remediation contractors who already use Mapei products for other remediation work, specifying Mapei for the renovation plaster stage offers supply chain consistency. Confirm the current Mape-Antique product names and system documentation with Mapei Australia before specifying — the Mape-Antique range has multiple products and the correct product selection depends on the application substrate, salt load and finish requirements. Confirm whether the product meets WTA 2-9-04 renovation plaster requirements with Mapei technical before specifying on a project with WTA compliance requirements.
Technical Properties
- Salt-tolerant formulation — designed to manage hygroscopic salts in rising damp walls during the drying-out period
- Vapour-permeable — allows the treated masonry wall to continue drying through the plaster layer
- Mapei national distribution — available through Mapei trade supply channels across Australian states
Limitations
- Confirm WTA 2-9-04 compliance with Mapei Australia technical before specifying where WTA-certified renovation plaster is required
- Old plaster must be stripped before application — do not apply over existing salt-contaminated plaster
- Confirm full system sequence with Mapei technical — including required undercoat, system thickness and drying intervals between coats
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Sika Vandex Cementitious Render Systems
Cementitious salt-tolerant render / slurry
System Description
Sika's Vandex range includes cementitious slurry and render products with salt tolerance for application to masonry walls with moisture and salt contamination. While the core Vandex Super product is a crystalline waterproofing slurry applied to stop water ingress under pressure, Sika also supplies cementitious render products in the Vandex range that can provide salt tolerance in rising damp remediation contexts. For rising damp walls, cementitious salt-tolerant renders may be specified where a harder, more robust surface finish is required compared to WTA renovation plasters, or where external render application is required. However, the pore structure and vapour permeability characteristics of standard cementitious renders differ from WTA-compliant renovation plasters — confirm that the selected Vandex product is appropriate for the specific rising damp remediation application with Sika Australia technical. Sika's national presence in Australia and comprehensive technical support make Sika products straightforward to specify and supply on larger strata remediation projects. Confirm current product range, application requirements and suitability for WTA-referenced renovation plaster applications with Sika Australia before specifying.
Technical Properties
- Cementitious formulation — harder and more abrasion-resistant than WTA renovation plasters — suited to areas with physical wear exposure
- Vandex crystalline technology may provide additional active waterproofing benefit in the render layer
- Available for both positive-side (internal face) and external render applications
Limitations
- Standard cementitious renders may have lower vapour permeability than WTA renovation plasters — confirm breathability with Sika technical for rising damp applications
- Confirm whether the product meets WTA 2-9-04 renovation plaster requirements before specifying in a WTA-referenced rising damp treatment system
- Old contaminated plaster must be stripped before application — do not apply over existing failing plaster
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Brand Equivalents
Salt-resistant renovation plaster equivalents. * Confirm WTA 2-9-04 compliance with manufacturer before specifying.
| System type | Remmers | Mapei | Sika |
|---|---|---|---|
| WTA 2-9-04 compliant renovation plaster — undercoat | SP I Renovation Undercoat | Mape-Antique* | — |
| WTA 2-9-04 compliant renovation plaster — finish | SP II Renovation Plaster | Mape-Antique* | — |
| Cementitious salt-tolerant render / slurry | — | — | Vandex range* |
Do not apply standard gypsum or cement plaster to rising damp walls — it will fail
- Gypsum plaster is soluble in the presence of moisture and salts — it will dissolve, swell and delaminate rapidly on a rising damp wall
- Standard Portland cement render is not salt-tolerant — it has insufficient pore volume to accommodate salt crystallisation and will spall and delaminate
- Only WTA 2-9-04 compliant renovation plasters (Remmers SP series or equivalent) have the confirmed pore structure to manage hygroscopic salt crystallisation during the wall drying-out period
- Stripping old plaster to masonry and replastering with standard materials without a WTA renovation plaster is the most common failure in rising damp remediation
Disclaimer
Information is general only. Product selection must be confirmed against project requirements, substrate condition, salt loading, manufacturer technical data sheets, and applicable standards including WTA 2-9-04. Do not apply renovation plaster without first completing chemical DPC injection. Do not rely on this reference as a substitute for professional advice.