The Building Appeals Board overrides concerns based on the year 2100 expected flood level in a win for a home owner seeking report and consent 

4 Feb 2025

In April 2024, the Owner of a property in Port Melbourne was refused consent for an “as designed” floor level by the Port Phillip City Council (“the Council”), based on a floor level requirement of 2.7m Australian Height Datum (AHD). This requirement was issued pursuant to Melbourne Water’s specified flood level of 2.4m AHD, which relied on an anticipated floor level for the year 2100, plus a freeboard. The proposed design had a floor level of 2.3m AHD and was said by Council to raise concerns of flooding and other safety risks. 

Subsequently, the Owner appealed the decision to the Victorian Building Appeals Board (“the Board”) under section 144(1)(a) of the Building Act 1993 (“the Act”). This appeal was successful, with the Board overturning the decision of the Council in favour of the Owner on the basis that the proposed floor level in the design adequately mitigated flood risk and offered improved safety compared to the existing dwelling.   

Owner’s Position 

The Owner’s position was that they relied on information given to them by Melbourne Water regarding the AHD for the property from May 2023 to June 2024. During this time, Melbourne Water issued multiple flood level certificates for the property (at the Owner’s request), all of which were citing a 2.0m AHD flood level. The Owner had based the design for the proposed dwelling on the first of such certificates under the assumption that the height of the ground floor (2.3m AHD) would be 300mm above the stipulated flood level.  

Additionally, the Owner argued that the proposed AHD by Melbourne Water was calculated while considering flood risk in the year 2100, a date that would have exceeded the expected life of the proposed dwelling. It was also argued that Melbourne Water had not engaged in the correct legislative process under the Water Act 1989 (“Water Act”) of declaring this flood level.  There was no public gazettal of the higher flood level.  

The Owner emphasized that raising the floor further would impose unnecessary costs and that the design height improved flood resilience compared to the existing dwelling. 

Port Phillip City Council & Melbourne Water’s Position 

The Council initially refused consent for the Building Permit based on information from Melbourne Water, who advised that the flood level for the site was 2.4m AHD.  This then required a minimum floor level of 2.7m AHD as per Regulation 153(6)(b) of the Building Regulations 2018 (“The Regulations”), when allowing for the freeboard distance.  As a result of this, the Owner’s proposal for the property was not compliant with this recommendation, because the proposed floor level was set at 2.3m AHD. 

Melbourne Water’s submissions defended its determination of an estimated 2.4m AHD flood level for the year 2100, based on supporting data indicating that the subject land was at risk of flooding resulting from storm surge / tidal inundation caused by rising sea levels.  

Although Melbourne Water acknowledged it had not officially declared this level under the correct legislative process, it argued that such declarations are not mandatory, and that councils can still rely on its advice under the Water Act.  

Moreover, Melbourne Water asserted that its flood level certificates provided earlier to the Owner were purely advisory and not valid authority for a proposed development. 

The Council adopted the position that it was incumbent on it to refer the report and consent application to a referral authority (ie Melbourne Water) and that its hands were effectively “tied” given the opposition from the referral authority.  Council would not allow a report and consent approval on that basis. 

Expert Evidence & Key Findings 

During the Owner’s submissions, they relied upon the expert evidence from a risk and flood management expert. This consultant provided an analysis of the flood risk of the Subject Land in an Expert Report. 

The Report considered the revised flood level of 2.4m AHD for the year 2100, stating that this figure was speculative and did not account for potential flood mitigation measures, including future sea wall enhancements.  

The Report reinforced the proposed dwelling’s floor level of 2.3m AHD, stating that it would demonstrate adequate resilience against current and future flood risks, including the year 2100 1% AEP storm tide risk raised by Melbourne Water.  

Additionally, the Report outlined the reduced risk to life, health and safety that the proposed development introduced, due to the finished floor levels being raised to 2.3m AHD, which was higher than the current floor level of the existing home at the property. 

Moreover, the flood risk expert emphasised the low risk associated with the development in the year 2100, with a key consideration being that there was no evidence to suggest that sea levels had risen in Hobson’s Bay in recent decades. In conjunction with this, the report opined that the site held a low flood hazard classification due to minimal amounts of floodwater that would likely present at the site. 

Life, Health and Safety Risks 

One of they key considerations from all parties involved was whether there would be life, health and safety risks to owners or occupants if the lowest floor level was built at 2.3m AHD. A critical issue under this consideration is regulation 153(4) of the Regulations, which states that:  

‘The relevant council must not give its consent under subregulation (2) if it is of the opinion that there is likely to be a danger to the life, health or safety of the occupants of the building due to flooding of the site’. 

As argued by the Owner and detailed in the expert evidence, the proposed floor level at 2.3m AHD would mitigate flood risks better than the existing dwelling and posed no significant safety risks. Additionally, flooding at the site would likely be short-lived, with no wave action, and would be classified as low hazard for adults and children. These claims were further supported by the Expert Report, which reinforced the view that there was minimal risk of flooding or hazard to life.  

The proposed garage floor was also a factor considered when judging life health and safety risks. Under regulation 153, class 10 buildings (non-habitable structures such as garages) are exempt from the requirement for council report and consent in flood-prone areas.  

However, Melbourne Water raised the possibility that the garage, due to its inclusion within the broader dwelling design and having habitable spaces above, might fall within the scope of Regulation 153. 

Despite the garage not being subject to the regulations, the Owner argued that its floor level does not affect the broader compliance of the dwelling and that habitable rooms above the garage at 5.17m AHD are well above flood levels.  

Findings 

The BAB found that the proposed dwelling at 2.3m AHD posed no significant life, health, or safety risks under Regulation 153(4). It accepted evidence from the Expert Report, demonstrating that any flooding at the site would likely be short-lived and low hazard, with the dwelling’s design offering enhanced safety compared to the existing structure. The inclusion of a first-floor refuge further supported the conclusion that occupants would be protected in extreme scenarios. 

While the garage was exempt as a Class 10 building, the BAB noted that its design posed no additional risks, with habitable rooms above at 5.17m AHD being well above flood levels. These findings collectively reinforced that the overall proposal sufficiently mitigated potential flood-related hazards. 

Furthermore, the BAB was not persuaded by Melbourne Water’s flood level projection for the year 2100, citing a lack of sound evidence and relevance to the specific issue. Additionally, the design life of the proposed new dwelling was a consideration in the decision on the flood level projection.  

Evidence presented in the Expert Report from the Australian Bureau of Statistics stated that the average design life of a dwelling is 62 years. When considered in the general context of the situation, the Board found it was possible that in 72 years (ie by the year 2100) the proposed dwelling would likely not be in service. 

The BAB substituted their findings for that of the Council and granted report and consent to allow the design to remain at the currently designed AHD level. 

Disclaimer  

The information provided in this article is for general informational purposes only. It does not constitute legal advice. For specific legal advice related to building regulations and compliance, please consult a construction lawyer.  

The images in this article were generated using ChatGPT-4 based on prompts provided by Lovegrove and Cotton Lawyers.