Water coming through skylights. Corroded metal and steel. Poor installation of waterproof membranes. Steel column ingress. Lead paint flaking off of steel beams because of corrosion. Rusted beams from water ingress. Visual observation of efflorescence on the façade from water penetration. And mould.

In compiling a report regarding building defects in multi-residential properties, these were the kind of Australian waterproofing issues reported to researchers Nicole Johnston from Deakin University and Sacha Reid from Griffith University.

In their report, these two researchers looked at the type of defects afflicting multi-residential buildings and the kind of defects which happen most typically. They reviewed 210 audit reports exposing defects from structures in Queensland, New South Wales and Victoria; did interviews with industry workers and looked at the regulatory process affecting building.

In this study, waterproofing was revealed as the third most common defect, constituting 11.46 percent of all issues. Frequent problems included membrane failures, defective membrane installation, paint failures, and an insufficient fall to shower areas.

This was not the first report showcasing waterproofing defects in new apartments. In 2012, a University of New South Wales survey of apartment owners discovered that 85 percent of those whose apartments had been built on or after 2000 had experienced or were aware of severe defects in their strata scheme. In that study, 42 percent were aware of internal water leaks in their strata scheme, while 40 percent knew of water penetration from the outside.

These issues were investigated in an article published by Helen Kowal, a partner specialising in property, planning, projects and strata at the legal firm Swaab. In her article, Kowal interviewed Paul Ratcliff, a general building consultant who works in the areas of waterproofing and diagnostic reporting and who is Managing Director of Paul Ratcliff Building and Waterproofing Pty Ltd.

Requirements in regards to waterproofing are established in Part F1 under Volume One in NCC 2019 and in Part 3.8 in NCC Volume Two. These specify that roofs and external walls, including openings surrounding doors, must prevent the penetration of water, which could elicit either dangerous or unhealthy conditions or undue dampness or deterioration of building elements.

Two relevant standards are Australian Standard AS 3740-2010 Internal Wet Areas and Australian Standard 4654.2-2012 External Wet Areas.

In the piece, Ratcliff stated that the rate of defective waterproofing can be explained by the deterioration of the quality of building in relation to the onset of private certification, and a failure to inspect work at vital stages.

He said that performance requirements must be more clearly defined in regards to the performance of the work.

Ratcliff says that waterproofing standards AS3740 – 2010 and AS4654.2 – 2012, referenced under the Deemed To Satisfy (‘DTS’) provisions in Section F of Volume One of the Code, are outdated and do not address problems which have arisen from complaints in tribunals and courts.

He suggests that the NSW Civil and Administrative Appeals Tribunal (in the case of NSW) could supply complaints-related data to the Australian Building Codes Board (ABCB) and SAI Global so that issues can be resolved.

Ratcliff feels that there needs to be more guidance in regards to the installation of ceramic tiles, the issue of con­trol of min­er­alised salt in tile screeds in bath­rooms, the con­trol of the move­ment of mois­ture through tile screeds, etc. While AS3740-2010 does acknowl­edge that mois­ture might cause dete­ri­o­ra­tion, it does not specify com­pliance with the per­for­mance require­ments of FP 1.7 of the NCC, which requires that water should not collect behind fittings and linings or into hidden spaces of sanitary compartments, bathrooms, laundries, etc. This, he says, creates an issue in which builders have built according to the DTS provisions but have not met the performance requirements of FP 1.7.

Beyond this issue, Ratcliff says that AS 3740 makes no distinction in the systems needed to waterproof bathrooms in the case of timber-framed bathrooms instead of ‘low movement’ construction, and concrete slab and brick wall arrangements. And no differentiation is made between materials that should be integrated into each kind of construction. He says that a different waterproofing system should be in place for each construction type.

To resolve these problems, Ratcliff recommends a stage of action over a six-year cycle.

Standards need to be updated to reflect standards and practices, with waterproofing being treated as an individual system. Certifiers need checklists, TAFEs should train waterproofers in the application of the systems, architects in the specification of the systems, builders in the installation of the systems, and certifiers in the inspection of the systems.

He also says that membranes need to be tested, their materials verified and their installation methods approved.

Overall, Ratcliff says that building codes also need to be revised, to lead to a drier—and more sustainable—Australia.