Everything property owners, builders, and strata managers need to know about waterproofing compliance in NSW. Issued by licensed contractors, flood tested, legally binding.
When a licensed waterproofing contractor completes work on a wet area in New South Wales, they are legally required to certify that the work complies with Australian Standard AS 3740:2021, Waterproofing of Domestic Wet Areas. This standard is referenced by the National Construction Code (NCC) and the Building Code of Australia. It sets binding minimum requirements covering membrane types, application thickness, drainage design, upstand heights, wet area geometry, and the junction treatment between walls and floors.
AS 3740 is not a guideline or best-practice recommendation. It is a mandatory technical standard. Work that does not comply with AS 3740 cannot receive a valid compliance certificate, cannot be legally certified by a licensed contractor, and may not be covered by home warranty insurance under the Home Building Act 1989.
The 2021 version updated requirements around drainage slope (minimum 1:60 fall to the outlet), expanded coverage rules for membrane application at junctions and upstands, and clarified the flood test protocol. Contractors working to the 2010 version without updating their practice may be issuing non-compliant work. Econyc’s technicians maintain current knowledge of AS 3740:2021 and work to its requirements on every job.
Under NSW Home Building Act requirements, a waterproofing compliance certificate must contain specific information to be legally valid. An incomplete or informal certificate does not provide the legal protection a full compliance certificate is designed to give.
A valid certificate must include the full name and licence number of the licensed waterproofing contractor, the name of the contracting company, the property address where work was completed, the date the waterproofing work was completed, the Australian Standard the work complies with (AS 3740:2021 or AS 4654.2:2012 for external areas), the membrane product used and its application rate or coverage, the date and result of the flood test including the water level held and duration, and the date the certificate was issued.
Certificates that are missing the licence number, product specification, or flood test result are not compliant. Certificates issued without the contractor having physically visited and tested the site are fraudulent. Econyc’s certificates contain all required fields and are issued within 24 to 48 hours of completed work and flood test.
Knowing when a waterproofing compliance certificate is required in NSW saves you from disputes, delays, and potential legal liability. Here is a complete guide to the situations where a certificate is required or strongly advisable.
New construction: every bathroom, laundry, shower enclosure, balcony, and external wet area in a new residential building requires waterproofing to AS 3740 or AS 4654.2, and a compliance certificate must be issued before tiling proceeds. Certifiers may include waterproofing as a hold point on the inspection schedule.
Renovation or bathroom remodelling: any work involving tile removal, membrane replacement, or new waterproofing in an existing wet area must be carried out by a licensed contractor who issues a certificate. The certificate is required before tiling proceeds.
Property sale: conveyancers increasingly request waterproofing certificates for apartments and recently renovated properties. An absence of certificates for wet areas can reduce buyer confidence, lower offers, or be a condition for the sale proceeding.
Strata renovations: owners corporation by-laws in most NSW strata schemes require a waterproofing compliance certificate as a condition of approval for any wet area renovation. The strata manager reviews the certificate before allowing tiles to proceed.
Insurance claims: in the event of a water damage claim involving a wet area, insurers may request proof that waterproofing was installed by a licensed contractor and certified. An absence of documentation can complicate or invalidate a claim.
Post-remedial repair: following remedial waterproofing work to correct a leak, a new certificate confirms the repair meets the current standard.
Our certification process is thorough, fully documented, and non-negotiable. Every step is followed on every job, regardless of scale.
A waterproofing certificate is only as reliable as the product it certifies. Econyc uses top-tier products from Normet, Sika, and Tremco, all of which carry full Australian technical data, independent test results, and manufacturer warranties that are valid when applied by trained contractors.
For internal wet areas, primary products include Sika TanDrain (a single-component, reinforced flexible waterproofing membrane for shower bases and walls), Sika SikaTite-N (a brush-applied membrane for upstands and junction treatment), and Tremco TREMproof 60 (a polyurethane liquid membrane for internal and external applications). For sealant joints within wet areas, we use Tremco Dymonic and Sikaflex Pro-3 for high-movement joints around screens, bases, and thresholds.
For external wet areas certified to AS 4654.2, we use Tremco TREMproof 201 or Sika SikaDeck-EZ, both of which are designed for exposed deck and balcony applications and carry appropriate elongation and weathering performance data.
When Econyc carries out the waterproofing work that is the subject of the certificate, our workmanship warranty applies. Bathroom and shower waterproofing carries a 5-year workmanship warranty. Balcony and external wet areas carry a 10-year workmanship warranty. Basement and below-grade systems carry a 7-year workmanship warranty.
All warranties are issued in writing alongside the compliance certificate and are transferable on property sale. The warranty is backed by our public liability insurance and covers defects in our application of the waterproofing system under normal use. It does not cover damage caused by subsequent building movement, structural issues outside the waterproofed area, or modifications made by others after our work is completed.
Can an unlicensed person issue a waterproofing certificate in NSW?
No. Only a holder of a current NSW waterproofing contractor licence issued under the Home Building Act can legally certify waterproofing work to AS 3740. Any certificate issued by an unlicensed person has no legal standing and does not provide the protections the Home Building Act is designed to give.
What happens if a builder or tiler waterproofs without a licensed contractor?
The waterproofing work is unlicensed and a certificate cannot legally be issued for it. If the work is later found to be defective, there is no legal recourse under the Home Building Act against the person who carried it out. The property owner bears all remediation costs. Econyc regularly carries out remediation of unlicensed waterproofing work in Sydney where this situation has arisen.
Is a waterproofing certificate required for every bathroom in a renovation?
Yes. If any waterproofing membrane work is carried out in a bathroom, regardless of whether it is the full floor or just the shower base, a certificate is required. Partial waterproofing of a wet area is not a lesser scope that avoids the certification requirement.
How long is a waterproofing certificate valid?
The certificate itself has no expiry date. It certifies that at the time of completion and testing, the work met the standard. The underlying waterproofing membrane has a physical lifespan, and Econyc’s workmanship warranty covers defects in our application for the warranty period.
Can I get a certificate for waterproofing done by a previous owner?
Only if the contractor who did the work issues one retrospectively after inspection and testing, or if a licensed inspector (such as Econyc) inspects the work, carries out a flood test, and certifies it based on the inspection outcome. Econyc can carry out independent waterproofing inspections and issue certificates where existing work passes flood test requirements.
Contact Econyc today for a free site inspection and fixed-price quote. Licensed, insured, and fully compliant with Australian waterproofing standards.