“Water penetration through skylights…issues with corrosion of metal / steel facades and structural beams, incorrect installation and application of waterproof membranes in bathrooms, steel column ingress, lead paint flaking off steel beams due to corrosion / rust of the beams from water ingress, visual observation of efflorescence on the façade everywhere from water penetration, mould inundation”

Such was the description of waterproofing problems in buildings throughout Australia given by one consultant to researchers Nicole Johnston from Deakin University and Sacha Reid from Griffith University for their report examining building defects in multi-residential properties released in July.

In their report, Johnson and Reid examined the nature of defects in multi-residential buildings and the types of defects which occur most frequently. To do this, they analysed 210 audit reports into defects from buildings across Queensland, New South Wales and Victoria; conducted interviews with industry participants and examined the regulatory environment in respect of building.

In their study, waterproofing was identified as the third most common defect, accounting for 11.46 percent of all problems. Common issues included membrane failures, defective membrane installation, paint failures and an inadequate fall to shower areas.

This was not the first report highlighting waterproofing deficiencies in new apartments. In 2012, a University of New South Wales survey of apartment owners found that 85 percent of those whose apartments had been constructed either on or after 2000 had experienced or knew of serious defects within their strata scheme. In that study, 42 percent knew of internal water leaks within their strata scheme whilst 40 percent were aware of water penetration from outside.

This raises question about why problems occur. Such issues were explored in a recent article published by Helen Kowal, a partner specialising in property, planning, projects and strata at law firm Swaab. In her article, Kowal interviewed Paul Ratcliff, a general building consultant who specialises in waterproofing and diagnostic reporting and who is Managing Director of Paul Ratcliff Building and Waterproofing Pty Ltd.

Requirements in respect of waterproofing are set out Part F1 under Volume One in NCC 2019 and in Part 3.8 in NCC Volume Two. These require that roofs and external walls including openings around doors must prevent the penetration of water which could cause either dangerous or unhealthy conditions or undue dampness or deterioration of building elements.

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

In the aforementioned article, Ratcliff said the rate of defective waterproofing can be attributed to several factors.

First, he says the quality of building generally has deteriorated with the rise of private certification. Many certifiers, he says, fail to inspect work at important stages.

Next, Ratcliff talks of an overreliance upon performance requirements which are not clearly defined. Whilst he acknowledges the role of performance requirements within the hierarchy of the National Construction Code, Ratcliff says these do not go far enough in describing the performance of the work.

As well, Ratcliff says waterproofing standards AS3740 – 2010 and AS4654.2 – 2012, which are referenced under the Deemed To Satisfy (‘DTS’) provisions in Section F of Volume One of the Code, are out of date and have failed to address issues which have arisen out of complaints in tribunals and courts.

With balcony or planter box leaks, for example, Ratcliff says AS4654.2-2012does not address any of the many issues which have risen repeatedly during complaints.  Instead, he says the NSW Civil and Administrative Appeals Tribunal (in the case of NSW) could provide complaints-related data to the Australian Building Codes Board (ABCB) and SAI Global so that reoccurring inadequacies are addressed. 

On AS3740-2010, he describes an issue which arose arose in a com­plex of 103 over 55’s units which were cat­e­gorised as adapt­able hous­ing. According to Ratcliff, neither AS3740 nor AS3958.1- 2007 ‘Guide to the installation of ceramic tiles’ addresses the issue of con­trol of min­er­alised salt in tile screeds in bath­rooms. Nor is there any guid­ance for builders on how to con­trol the move­ment of mois­ture through tile screeds. Whilst AS3740-2010 acknowl­edges that mois­ture may cause dete­ri­o­ra­tion, it does not specify how to com­ply with the per­for­mance require­ments of FP 1.7 of the NCC which requires that water should not penetrate either behind fittings and linings or into concealed spaces of sanitary compartments, bathrooms, laundries and the like. This, he says, creates a situation whereby builders have built according to the DTS provisions yet have failed to meet the performance requirements of FP 1.7.

Beyond this, Ratcliff says AS 3740 makes no distinction in the systems which are required for waterproofing bathrooms in the case of timber framed bathrooms as opposed to ‘low movement’ construction such and concrete slab and brick wall arrangements. Nor from a manufacturing perspective is there any distinction between the materials which should be used for each type of construction.

This, he says, is problematic. To ensure that builders, architects and designers have confidence in using the DTS provisions, there should be a different system in place for waterproofing for each of the different construction types, he says.

To address these issues, Ratcliff talks of staged action over a six year cycle.

Immediately, aforementioned standards need to be brought up to date and to reflect standards and practices which should be acceptable under a proper and workmanlike manner as opposed to mere minimum standards. In doing this, he says updated standards should adopt a systems approach which would treat waterproofing as a system. Following on from that, there could then be a checklist which certifiers could follow to check waterproofing.  This, he says will enable TAFEs to train waterproofers in application of the systems, architects to specify systems with confidence that they will work, builders to understand how systems should be installed and certifiers to have a checklist and know what to inspect.

Such a process, he says, would take two to three years to implement. Since waterproofing defects typically take several years to manifest themselves, better outcomes would become noticeable after around three further years once the changes have been bedded down.  

A further problem involves faulty membranes. Australia, Ratcliff says, is the ‘dumping ground’ for waterproofing membranes which have not been tested by either the CSIRO or BRANZ and turn out to be non-complaint with standards.

As well, data sheets provided by manufacturers often fail to provide builders and designers with the information necessary to determine the suitability of products for particular uses.

To address these issues, he would like a register of membranes which have been tested to relevant standards along with standardised data sheets to provide comparable information for product selection. Membranes which are proven not to be fit for purpose would be removed from the register.

This, Ratcliff says, will help to incentivise manufacturers to ensure that membranes are installed by approved applicators, waterproofing is installed correctly as per data sheets and that installed membranes are inspected before installation warranties are issued.

“Three years after imple­ment­ing a sys­tems approach into the Aus­tralian Stan­dards you would start to see a reduc­tion in claims,” Ratcliff wrote in the aforementioned article.

“Water­proof­ing defects don’t nor­mal­ly man­i­fest until year three but, you would find a change in the indus­try after year three and after year six, you would see a sharp decline in water­proof­ing defects.”

Asked about changes in NCC 2019, Ratcliff says the new building code does little to address underlying problems.  Nevertheless, he is currently working with Standards Australia on revisions to AS 3740 and 4654.2. These are hoped to be included in the next update of the NCC.

He is scornful about Government willingness to address core issues. The outcome of a recent ‘hackathon’ looking into home building compensation insurance in New South Wales was merely that the Government would look at raising premiums for builders in high-risk areas, he says.

Ratcliff is not alone in his worries. Attendees at a Master Builders Association Waterproofing Advisory Panel last October raised concern in relation to 53 problems spanning across seven areas.

To name a few, these include:

  • A lack of expertise in regard to waterproofing on the part of designers, builders and certifiers.
  • A lack of training in waterproofing within building courses and an absence of requirements for builders to undertake waterproofing training.
  • Aforementioned standards being out-of-date (not updated since 2010 in the case of AS 3740 Internal Wet Areas and since 2012 in the case of Australian Standard 4654.2 External Wet Areas) and being poorly managed with inactive technical committees.
  • A lack of explanation in the standards about different membrane types and where different types of membranes should be applied.
  • A lack of guidance within the standards about how waterproofing should be installed and applied.
  • Certifiers not inspecting waterproofing quality and lacking expertise to conduct waterproofing checks.
  • A lack of regulation for waterproofing membranes and the existence of membranes on the market with fail to provide an effective waterproofing solution.
  • Design and construct contracts allowing unregulated changes to construction contracts.
  • Liquidated damages potentially being more significant to the builder than getting the work performed with skill and care.
  • Architects and engineers not being trained in waterproofing and flashing design, installation and assessment.
  • An absence of subjects that are specific to waterproofing in current building courses.
  • A lack of a mandatory requirement for builders to undertake core waterproofing and flashing CPD training.
  • A lack of uptake in apprentice level training in waterproofing.
  • An absence of a definition as to how long waterproofing should remain serviceable. Most consumers expect waterproofing should last longer than 7 years.

In response, that group called for several changes. These include better education for designers, builders and waterproofing contractors; waterproofing design to be performed by architects, engineers or specialised consultants; changes to the waterproofing licensing regime to reflect different market segments (internal, external and remedial); compulsory annual training in waterproofing best practice for builders, architects, engineers, certifiers and waterproofing contractors; updating and upgrading of standards to reflect best practice methods; mandatory flood tests and mandatory inspections of the substrate prior to the waterproofing membrane being installed; the introduction of registers for membrane suppliers and installers and ten-year warranties for all membranes.

Australia suffers from serious issues in respect of waterproofing.

To address these, action is needed in several areas.