Inner and middle-Melbourne areas have been identified as hotspots in terms of serious defects relating to water related ingress and mould in new homes and apartments, the latest research across Victoria has found.

But significant problems are also occurring in outer urban growth areas where massive volumes of new developments are underway.

Published by building science firm RIC Solutions in conjunction with the Victorian Building Authority (VBA) and Domestic Building Disputes Resolution Victoria (DBDRV), the latest research aimed to identify the causes, nature and extent of problems which contribute to damage related to water ingress and mould across newly built residential developments in Victoria.

In particular, the study examined 6,299 de-identified residential building dispute cases that were submitted to DBDRV over the five-year period from July 2018 until June 2023 which involved at least one defect relating to water ingress or indoor mould.

From these, 49 case studies were examined in greater detail.

Overall, the research found that the highest rates of water related defects were found in inner and middle areas of Melbourne.

Indeed, the top five areas for water defect rates are Darebin in Melbourne’s inner north.  Maribyrnong in the inner west, Manningham in the middle north-east, Mooney Valley in the inner-north and Glen Eira in the inner-southeast.

For every 100 building permits that were issued during the aforementioned five-year period, the number of residential disputes that involved at least one water related item in these local government areas during the period came in at 7.09, 6.83, 6.67, 6.07 and 5.58 respectively.

Meanwhile, significant problems are also occurring in urban growth areas.

Indeed, local government areas such as Wyndham, Melton, Hume, Whittlesea and Casey all have above-average rates of water related damage (see chart).

The prevalence of damage in these areas is particularly concerning in light of the volume of development that is occurring in these areas.

When measured according to overall numbers, Wyndham has the greatest number of water related disputes followed by Casey, Melton, Whittlesea and Hume.

Whilst this is not mentioned in the report, it is likely that the high rate of water defects in inner and middle suburbs relates to the relatively high rate of low and medium rise apartments which are being constructed in these areas.

In these types of dwelling, there have been significant problems associated with water ingress into apartments from balconies.

In regard to urban growth areas, the report notes that the high rates of defects could potentially be attributable to the significant prevalence of volume builders in these areas.

The report also found that:

• Notable issues from the case studies were moisture accumulation from a lack of site drainage, non-compliant roofing or roof plumbing, wet walls in basement car parks, moisture ingress on balconies and from waffle raft slabs, and leaks from internal wet areas.
• Where building or occupancy permits were available to the researchers for analysis, there were no performance solutions documented that related to internal/external waterproofing, roof plumbing or site drainage.
• In bathrooms, the absence of a waterstop was most the most frequently noted issue. Waterproofing membrane failures were less frequent, perhaps due to the requirement of more specialised equipment or more invasive or destructive testing methods.
• While access to roofs was often avoided and discouraged for safety reasons, issues with non-compliant rain heads and sump overflows were noted from ground level. Reports provided by third party inspectors also highlighted issues with poor roof tiling and gutter installations.
• On balconies, issues were most often related to waterproofing membrane failures, however design documentation lacking details for parapet wall junctions and non-compliant design of vertical upward termination heights and penetrations were also noted.
• The causes of condensation in the case studies were resultant from the presence of thermal mass (that became cold and remained that way), lack of air movement in bathroom and kitchens, thermal bridging across a wall or ceiling, and thermal bridging in single glazing.
• Site drainage issues were varied and included the ground saturation of clay soils with low permeability leading to hydrostatic pressure on slab vapour barriers, the lack of perimeter drains around a building’s external walls and the construction of planting strips in contact with external walls or within close proximity of footings.
• While none of the issues with slabs were directly associated with an identified moisture problem, bulging edges from formwork blowout or substrate containing rubbish may lead to excessive building movement which permits water ingress even before the building manifests structural concerns.
• Missing weepholes were the most frequently appearing weatherproofing non-compliance, followed by issues of direct water ingress through inadequate seals around cladding junctions, windows and doors.

(image provide in aforementioned report showing verandah falling inward toward external walls)

The report made several recommendations.

These include:

• development of minimum health-related building standards
• improvements to vocational and higher education of building practitioners
• development of new minimum documentation criteria around waterproofing, weatherproofing, storm-water drainage and condensation; and
• adoption of digital tools and technologies to capture and document the multiple stages of weatherproofing and waterproofing to supplement mandatory inspections.

In response, the VBA has used the insights gained for the report to inform its activities across several areas.

These include the regulator’s input to proposed changes to the national Construction Code and regulatory changes in Victoria as well as its inspections program and development of industry and consumer materials.

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