Waterproofing - Wet Areas SWMS

Waterproofing of wet areas — bathrooms, laundries, ensuites, kitchens and balconies — involves the application of liquid membranes, primers, bond breakers and sealants to substrates prior to tiling. The work is performed in confined, poorly ventilated rooms where solvent-based primers, moisture-cured polyurethanes and epoxy membranes release volatile organic compounds, isocyanates and flammable vapours. Applicators kneel or crouch on hard, often wet surfaces for extended periods, work near open electrical points and hot water rough-ins, and frequently follow other trades whose dust and debris contaminate the substrate. Failure of the membrane is the leading cause of internal water damage claims in NSW residential construction, and failure of respiratory or fire controls during application has caused documented poisoning and flash-fire incidents.

Under the Work Health and Safety Regulation 2025 (NSW), waterproofing in enclosed wet areas engages section 291 as high risk construction work where a contaminated or flammable atmosphere may exist during solvent primer and membrane application. Section 299 requires a Safe Work Method Statement to be prepared before the work commences, kept available for inspection, and complied with. Controls follow the hierarchy in section 36 of the Regulation — eliminating solvent products where a water-based equivalent performs, substituting low-VOC systems, engineering forced ventilation, and finally applying administrative controls and respiratory PPE.

Hazards identified

12 hazards covered, sorted by priority.

Control measures

Hierarchy-of-controls order: elimination → substitution → isolation → engineering → administrative → PPE.

1. 1Eliminate solvent-based primers where the substrate permits by specifying water-based acrylic or polymer-modified cementitious membrane systems compliant with AS 4858 for the wet-area application.
2. 2Substitute high-VOC solvent primers with low-VOC or single-component water-based primers from the same manufacturer's warranted system; retain the Safety Data Sheet on site for every product used.
3. 3Isolate all ignition sources before opening solvent containers: turn off gas hot water units, extinguish pilot lights, de-energise the wet-area circuit at the switchboard and lock out in accordance with AS/NZS 4836, and prohibit smoking within 6 m.
4. 4Provide continuous mechanical extraction ventilation drawing vapour out of the wet area to atmosphere — a portable ducted extract fan positioned low (vapours are heavier than air) with the doorway used as make-up air — for the duration of application and initial cure.
5. 5Test the atmosphere with a calibrated photoionisation detector or LEL meter before entry when working in below-ground bathrooms or windowless internal rooms; do not enter or work if LEL exceeds 5%.
6. 6Confirm the substrate is free of asbestos before mechanical preparation: for pre-2004 buildings review the asbestos register required under section 425 of the WHS Regulation 2025 (NSW), and engage a licensed removalist where ACM is present.
7. 7Control residual silica dust from prior trades by HEPA H-class vacuuming (compliant with AS/NZS 60335.2.69) and wet wiping the substrate before primer application; do not dry sweep.
8. 8Wear organic vapour respiratory protection selected under AS/NZS 1715 and fit-tested to AS/NZS 1716 — a half-face respirator with A2P2 cartridges for water-based products and a full-face or air-supplied respirator for isocyanate-containing polyurethanes.
9. 9Wear chemical-resistant nitrile or butyl gloves, safety eyewear to AS/NZS 1337.1, long sleeves, and knee protection; provide immediate access to eyewash and a washing facility as required under section 41 of the WHS Regulation 2025 (NSW).
10. 10Restrict access to the wet area during application and for the manufacturer's stated re-entry period; post signage at the doorway identifying the product, hazard and time of re-entry, and prohibit other trades from working overhead or adjacent.
11. 11Implement a buddy system with radio or phone contact at agreed intervals when a single applicator is working in a sealed room; do not permit lone work during solvent primer application.
12. 12All workers hold CPCCWHS1001 (White Card); the SWMS is consulted with workers under section 47 of the WHS Act 2011 (NSW), signed before work starts, and reviewed under section 302 of the WHS Regulation 2025 (NSW) whenever products, ventilation arrangements or personnel change.

Applicable Codes of Practice

High-Risk Construction Work triggered

Worked example

A tiling subcontractor is engaged to waterproof and tile eight ensuite bathrooms in a three-storey residential development in Kogarah. Each ensuite is approximately 3.2 m² with no window and a single doorway. The specified system uses a solvent-based epoxy primer followed by a two-component polyurethane membrane. Before work commences the site supervisor consults the two applicators on the SWMS, confirms both hold CPCCWHS1001, and verifies the pre-2004 asbestos register shows no ACM in the wet-area substrates. The gas hot-water unit servicing that riser is isolated and tagged, and the ensuite circuit is locked out at the switchboard. A portable ducted extract fan is positioned at floor level with ducting run to the balcony; make-up air enters through the propped door. Applicators wear full-face respirators with A2P2 cartridges (fit-tested), nitrile gloves and knee pads. A PID meter is used to spot-check the atmosphere. The lead applicator remains in radio contact with the site supervisor at 15-minute intervals. Access to the level is controlled by signage and the re-entry period stated on the SDS is enforced before tilers return. The SWMS is re-signed when the builder later substitutes a water-based primer for the ground-floor bathrooms, triggering a section 302 review.

Related legislation

• Work Health and Safety Act 2011 (NSW)
• Work Health and Safety Regulation 2025 (NSW)
• Home Building Act 1989 (NSW) — waterproofing licensing requirements
• Protection of the Environment Operations Act 1997 (NSW) — disposal of solvent-contaminated waste
• Dangerous Goods (Road and Rail Transport) Act 2008 (NSW) — transport of flammable primers
• Environmental Planning and Assessment Act 1979 (NSW) — National Construction Code compliance for wet areas

Frequently asked questions