AS 3740 CERTIFIED WATERPROOFERS
Compliant waterproofing for bathrooms, showers, balconies, laundries, and podium decks across Sydney. Every job comes with a certificate of compliance. Licensed (151440C), 25+ years experience.
WATERPROOFING STANDARD
AS 3740 is the Australian Standard that governs waterproofing of domestic wet areas, including bathrooms, ensuites, showers, laundries, and balconies. It sets out exactly which surfaces must be waterproofed, how high the membrane must go, what membrane systems are acceptable, and how they must be applied.
Compliance is not optional. The National Construction Code requires wet-area waterproofing to meet AS 3740 for any new or significantly renovated bathroom in Australia. In NSW, non-compliant waterproofing can void home insurance cover for water-damage claims and become a costly problem at resale.
Proper compliance means priming the substrate, applying the membrane to the correct thickness across the required area, installing perimeter cant strips at every floor-to-wall junction, maintaining correct falls to the drain, and issuing a formal certificate of compliance on completion. That is exactly how our team waterproofs every job.
NSW Contractor Licence
151440C
THE REAL RISK
A failed or non-compliant waterproofing membrane is not an aesthetic problem. It is a structural one. Water ingress behind tiles works silently: tiles begin to lift and hollow within 2-5 years as the bond coat fails, mould establishes itself inside the wall cavity, and timber subfloors rot from beneath.
When homeowners discover the damage, it is rarely a small patch repair. The entire bathroom usually needs to come out, any rotted framing or sheeting needs replacing, new compliant waterproofing is installed, and everything is tiled again. The cost is typically 2-3 times the original renovation cost, and the disruption is significant.
Insurance claims for water damage are frequently denied when there is no waterproofing certificate of compliance on file. Without it, insurers can argue the wet area was not built to code, which removes their obligation to pay. A certificate costs nothing extra on our jobs. It is standard.
The cheapest waterproofing is always the compliant waterproofing done right the first time. The most expensive is the cut-corner job you have to rip out and redo 3 years later.
HOW WE WORK
A structured 5-step process, applied the same way on every job, from a small ensuite to a large balcony deck.
The surface is cleaned back, all voids and low spots are filled and levelled, and perimeter cant strips are installed at every floor-to-wall junction. This is the foundation everything else depends on.
We apply the membrane system primer specified by the manufacturer, at the correct coverage rate, and allow it to fully dry before touching it. Skipping primer is one of the top causes of membrane delamination.
The liquid membrane is applied full-area to the manufacturer-specified wet film thickness, covering the floor, the walls up to the required height, all perimeter cant strips, and all penetrations.
A second full coat is applied perpendicular to the first, eliminating any pinholes or thin spots. We allow a minimum 24-hour cure before any tiling starts, no exceptions.
On completion, we issue a written certificate of compliance. It lists the membrane product, batch number, application dates, applicator details, and photos of the finished membrane. You keep this document.
WET AREA TYPES
We waterproof all domestic wet areas under AS 3740, including internal and external applications.
Full-area waterproofing to AS 3740 for both floor and wall zones, including around all penetrations and the perimeter. We waterproof the floor and wet wall areas regardless of tile height.
Hobless and walk-in showers require a larger waterproof zone and correct falls to prevent water escaping the shower area. We design the membrane layout to suit the shower format and drain position.
Laundry floors and the areas behind and beside the tub need compliant waterproofing, particularly where the floor meets the wall and around waste penetrations. We waterproof to the full AS 3740 requirement.
External balconies and podium decks are waterproofed using systems rated for UV exposure and thermal movement. Correct falls to drainage and proper perimeter detailing are critical and always included.
Pool surrounds are a high-exposure wet area that need a membrane capable of handling constant wet-dry cycling and chemical exposure. We select products appropriate for the specific pool environment.
Full wet rooms and spa enclosures require waterproofing across all 4 walls, the full floor, and any ceiling areas exposed to direct water contact. We treat these as a completely sealed membrane envelope.
BEFORE & AFTER
Drag the slider to reveal the transformation. Every job completed by S & T Tiling Renovations across Sydney.
Bathroom waterproofing to finished tiling
Full bathroom strip-out to finished renovation
DOCUMENT YOU KEEP
The certificate of compliance is a formal document we issue in writing on completion of every waterproofing job. It records the membrane product used, the product batch number, the application dates, the applicator details, and photos of the finished membrane before tiling begins. It is the documented proof that the waterproofing was installed correctly.
For council inspections and owner-builder projects, the certificate satisfies the waterproofing documentation requirement. Without it, you cannot demonstrate compliance with AS 3740 after the membrane has been covered by tiles.
For home insurance, the certificate is critical. Insurers increasingly require evidence of compliant waterproofing before honouring water-damage claims. A claim made years after a bathroom renovation is far more likely to be paid when a certificate exists on file. Without one, the insurer can argue the wet area was not built to code.
At resale, the certificate adds demonstrable value. A prospective buyer's building inspector or solicitor may ask for waterproofing documentation. A certificate from a licensed applicator (151440C) is a clean, professional answer. You keep this document permanently. We recommend keeping it with your other property records.
FAQ
AREAS WE SERVICE
Based in Marrickville, we waterproof bathrooms right across Sydney's Inner West. Waterproofing is included in every bathroom renovation we complete. Find bathroom renovations in your suburb.
FREE QUOTE
Tell us about your wet area and we'll get back to you within 2 hours during business hours with a written, obligation-free quote. Every job includes AS 3740 compliant waterproofing and a certificate of compliance.
