Repair Systems — 03 — Facade & External Envelope
Biocide and surface preparation systems
Algae, lichen, mould and fungal growth on facade surfaces must be killed and removed before repainting. Painting over live biological growth causes premature paint failure — the organisms continue to grow beneath the coating, causing blistering and delamination. Biocide wash must be applied, allowed to dwell, then washed off before priming.
What are biocide surface preparation systems?
Biocide surface preparation products are chemical treatments applied to exterior facades to kill mould, mildew, algae, moss, and lichen before surface preparation and repainting. They are a mandatory first step in any exterior repainting specification where biological growth is present — failure to treat biological growth before repainting is a primary cause of premature coating failure on Australian strata buildings.
Product Reference
6 products — 6 brands — biocide surface preparation systems — scroll to view all
TODO: owner confirm — Dulux Weathershield Mould & Mildew Cleaner (exact current AU product name unconfirmed — could not confirm a dedicated 'Weathershield Mould & Mildew Cleaner' product on dulux.com.au at time of verification — Dulux AU surface preparation guidance references generic bleach solution or Sugar Soap for pre-paint cleaning — confirm whether a dedicated Dulux biocide surface wash product exists in the current AU range with Dulux technical)
TODO: owner confirm — Biocide pre-paint surface wash — masonry and render (product name unconfirmed — see name field)
System Description
Dulux Weathershield Mould & Mildew Cleaner is a concentrated biocide surface wash formulated for use on exterior masonry, render, and painted surfaces as part of the surface preparation process before repainting. It kills mould, mildew, and algae present on the facade, treating the biological growth at the surface and subsurface level before the old coating is stripped or new coating is applied. Applied as a diluted solution by brush or spray, left to dwell on the surface, then rinsed off before coating. The product is part of the Dulux Weathershield system and is designed to work with Dulux Weathershield exterior primers and topcoats. Biocide pre-treatment is a mandatory step before repainting facades with biological growth — failure to treat before repainting results in rapid regrowth through or under the new coating. Confirm current dilution ratios, dwell time, and safety requirements from the current Dulux Weathershield Mould & Mildew Cleaner TDS before use.
Technical Properties
- Concentrated formula — dilute with water per TDS before application to masonry and render
- Kills mould, mildew and algae at the surface — mandatory pre-paint step for biologically contaminated facades
- Apply by brush, roller or spray — allow dwell time per TDS — rinse off before priming and repainting
Limitations
- Does not provide long-term biocide residual protection — anti-fungal topcoat required after treatment for residual protection
- Will not remove physical build-up of heavy biological matter — scrub or pressure wash before and after treatment
- Not a substitute for thorough surface preparation — all loose paint must still be removed before repainting
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
System Description
Wattyl Kill Mould is a bleach-free biocide treatment formulated for application to mould, mildew, and algae-affected surfaces on exterior and interior substrates before painting. The bleach-free formula is particularly suited to strata facade repainting projects where bleach-based treatments may cause damage to vegetation below, adjacent surfaces, or drainage infrastructure. It is applied directly to the affected surface, left to dwell to kill biological growth, then rinsed off or wiped down before priming and repainting. Kill Mould is used as part of the Wattyl surface preparation system ahead of Wattyl Solagard or other exterior topcoat systems. Confirm dilution instructions, dwell time, and surface rinsing requirements from the current Wattyl Kill Mould TDS before use. Always use appropriate PPE when applying biocide products on scaffold.
Technical Properties
- Bleach-free formulation — reduced risk of bleach damage to vegetation, adjacent surfaces or site drainage
- Kills mould, mildew and algae on exterior masonry, render and painted surfaces
- Apply undiluted or diluted per TDS — dwell time kills biological growth — rinse before repainting
Limitations
- Bleach-free — may require longer dwell time to achieve equivalent kill rate to chlorine-based products on heavy growth
- Not a residual biocide — anti-fungal topcoat required after treatment for ongoing biological protection
- Physical scrubbing of heavy mould and algae build-up required before and after chemical treatment
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
TODO: owner confirm — Taubmans Mould Killer (CRITICAL: the current Taubmans mould product appears to be 'Taubmans Advanced Adhesion & Mould Blocker' which is a PRIMER/PREPCOAT that is applied and LEFT ON — it is NOT a biocide rinse-off wash — the card describes a concentrated dilutable wash product, which does not match the current product type — confirm with Taubmans technical whether a separate biocide rinse-off wash product exists in the current Taubmans AU range)
TODO: owner confirm — Concentrated biocide surface wash — exterior pre-paint prep (current Taubmans mould product may be a primer/prepcoat, not a rinse-off wash — confirm product type with Taubmans technical)
System Description
TODO: owner confirm — CRITICAL PRODUCT TYPE MISMATCH. The current Taubmans mould product found on taubmans.com.au at time of verification is 'Taubmans Advanced Adhesion & Mould Blocker' — this is a PRIMER/PREPCOAT that is applied to the surface and LEFT ON as the primer coat. It is NOT a concentrated biocide wash that is rinsed off. The card as written describes a rinse-off biocide wash product which does not match the current product type. If a rinse-off biocide wash is required for pre-paint surface preparation, a different product (e.g. Wattyl Kill Mould, or a generic biocide wash) must be specified instead. Confirm with Taubmans technical whether a separate pre-paint biocide wash product exists in the current Taubmans AU range before retaining this product on the card.
Technical Properties
- Concentrated formula — dilute per TDS before application to exterior masonry and render surfaces
- Kills mould, mildew and algae — mandatory pre-paint biocide step for biologically affected facades
- Apply by brush, roller or garden spray — dwell and rinse as per TDS before priming
Limitations
- Requires thorough rinsing before primer application — residual chemical may affect adhesion
- Not a standalone treatment — anti-fungal topcoat required for ongoing biological protection after treatment
- Does not replace mechanical removal of heavy biological build-up before chemical treatment
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
TODO: owner confirm — Haymes Mould Wash (exact current AU product name unconfirmed — could not confirm a product named 'Haymes Mould Wash' on haymespaint.com.au at time of verification — confirm current biocide surface wash product name in the Haymes range with Haymes technical)
TODO: owner confirm — Biocide surface wash — exterior masonry and render — Australian-made (product name unconfirmed — see name field)
System Description
Haymes Mould Wash is an Australian-manufactured biocide surface preparation product for treating mould, mildew, and algae-affected exterior facades before repainting. Used as part of the Haymes surface preparation system, it is applied to affected exterior masonry and render surfaces to kill biological growth present on or within the surface coating layer, as a mandatory step before primer and topcoat application. The product is particularly well positioned for projects specifying the full Haymes exterior painting system — Haymes Mould Wash, Haymes exterior primer, and Haymes Extreme Shield topcoat — to ensure system compatibility. Confirm current dilution ratio, dwell time, rinsing requirements, and PPE from the current Haymes Mould Wash TDS before use.
Technical Properties
- Australian-manufactured — part of the Haymes surface preparation system
- Kills mould, mildew and algae on exterior masonry, render and painted surfaces before repainting
- Dilute and apply per TDS — dwell and rinse before primer application
Limitations
- Haymes distribution strongest in Victoria and regional — confirm national availability with local paint supplier
- Not a residual biocide — specify anti-fungal topcoat for ongoing biological protection after treatment
- Heavy biological build-up requires mechanical scrubbing before and after chemical treatment
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
TODO: owner confirm — Mapei Mapecide (WRONG PRODUCT NAME — 'Mapecide' not found on mapei.com/au at time of verification — the Mapei AU biocide/mould product found is 'Mapei Ultracare Mould Remover' (tile and surface product) — confirm whether 'Mapecide' exists in the current Mapei AU range or whether the correct product for facade biocide preparation is a different Mapei product — confirm with Mapei Australia technical)
TODO: owner confirm — Professional biocidal wash — exterior masonry and concrete surfaces (product name 'Mapecide' not confirmed on Mapei AU — see name field)
System Description
TODO: owner confirm — 'Mapecide' could not be confirmed as a current product on mapei.com/au as of verification date. The product name on this card requires verification with Mapei Australia technical. Mapei does supply professional biocidal products for facade preparation in some markets — if a Mapei biocide product is available in Australia it would be well suited to the facade restoration and strata remediation market where heavy or persistent biological contamination must be treated before facade repainting. Confirm the correct current Australian product name and TDS with Mapei Australia technical before retaining or using this card.
Technical Properties
- Professional-grade biocidal wash — kills mould, algae, moss and lichen on masonry, render and concrete
- Suitable for heavy and persistent biological contamination on facades requiring remedial restoration
- Dilutable concentrate — apply per TDS by brush or spray — dwell and rinse
Limitations
- Specialist product — available through trade supply, not general retail channels
- Confirm current Australian product name and formulation with Mapei Australia technical before specifying
- Not a topcoat residual biocide — anti-fungal coating required after treatment for ongoing protection
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Solver Mould Wash
Biocide pre-paint surface wash — exterior masonry and render
System Description
Solver Mould Wash is a biocide surface preparation product for treating mould, mildew, and algae on exterior masonry and render facades as part of the pre-paint surface preparation process. It is used ahead of Solver exterior primers and topcoats including Solver Permalastic and Solver Super Trim systems. Applied by brush or spray as a diluted solution, left to dwell on the affected surface to kill biological growth, then rinsed before priming and topcoat application. Solver has strong trade distribution networks in Victoria and eastern Australia. Confirm current product formulation, dilution ratios, dwell time, rinsing requirements, and PPE from the current Solver Mould Wash TDS before use on a remedial facade project.
Technical Properties
- Biocide surface wash — kills mould, mildew and algae on exterior masonry, render and painted surfaces
- Dilutable concentrate — apply per TDS ratios — dwell and rinse before repainting
- Part of the Solver exterior painting system — compatible with Solver exterior primers and topcoats
Limitations
- Confirm current product name and formulation with Solver trade before specifying
- Not a residual biocide — anti-fungal exterior topcoat required for ongoing protection after treatment
- Heavy biological build-up requires physical scrubbing before and after chemical treatment
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
System Comparison
Side-by-side comparison of biocide surface preparation systems. Confirm all product selections against the current manufacturer TDS before specifying.
| Product system | Brand | Type | Bleach-free | Targets | Substrate | Dilutable | Primary use |
|---|---|---|---|---|---|---|---|
| Weathershield Mould & Mildew Cleaner | Dulux | Biocide wash | Confirm TDS | Mould, mildew, algae | Masonry, render, painted | Yes | Benchmark pre-paint biocide — Dulux system — wide availability |
| Kill Mould | Wattyl | Biocide wash — bleach-free | Yes | Mould, mildew, algae | Exterior and interior surfaces | Confirm TDS | Bleach-free option — reduced site risk — Wattyl system |
| Mould Killer | Taubmans | Concentrated biocide wash | Confirm TDS | Mould, mildew, algae | Masonry, render, painted | Yes — concentrated | Taubmans system prep — exterior facade repainting |
| Mould Wash | Haymes | Biocide surface wash | Confirm TDS | Mould, mildew, algae | Masonry, render, painted | Yes | Haymes system — VIC/regional — Australian-made |
| Mapecide | Mapei | Professional biocidal wash | Confirm TDS | Mould, algae, moss, lichen | Masonry, concrete, render, stone | Yes — concentrate | Specialist remedial — heavy biological growth including lichen |
| Mould Wash | Solver | Biocide surface wash | Confirm TDS | Mould, mildew, algae | Masonry, render, painted | Yes | Solver system prep — VIC and eastern Australia |
Do not confuse biocide and surface preparation systems with:
- Alkali-resistant primers — the alkali primer is the first film-forming coat applied after the surface is washed, dried and treated; the biocide wash must be completed and washed off before primer application begins
- Penetrating consolidant primers — consolidants bind loose and friable substrate particles to provide a sound base for topcoat; they do not kill mould, algae or lichen and are not a substitute for pre-paint biocide treatment
- Household bleach or detergent washes — household bleach (sodium hypochlorite) at domestic concentrations is not a registered pre-paint biocide; it may partially kill surface growth but does not provide the dwell time or formulated active needed for coating preparation
- Mould-resistant paint additives — some topcoats contain in-can biocide additives that resist mould re-growth after painting; these are not a substitute for pre-paint biocide treatment of existing biological contamination
- Pressure washing alone — high-pressure washing removes loose biological material but does not kill residual spores or root systems embedded in porous substrates; biocide application after washing is required before repainting
Disclaimer
General technical information only. Biocide products must be handled in accordance with the Safety Data Sheet — use appropriate PPE. Biocide residue must be fully washed from the surface before painting. Confirm dilution rate, dwell time and washoff requirements from the current manufacturer TDS.