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WA builder fined for hidden granny flat modifications
The Western Australian Building Services Board has fined a building company thousands after it failed to inform clients about altered granny flat plans to comply with council requirements.
Prestige Renovations and Granny Flats Pty Ltd was fined $5,000 for negligent conduct, which is a disciplinary matter under Western Australia’s building registration laws.
The matter came as granny flats have gained popularity in recent years, with two-bedroom secondary dwellings in some states now earning investor-grade income.
According to information presented to the Western Australian board, Prestige was contracted in 2023 to construct an 89.6 sqm granny flat at a Singleton property.
Prestige’s building application was initially refused by the City of Rockingham because the proposed plans did not comply with the residential design code (R-Code) for detached ancillary dwellings.
To comply with the council’s requirements, the company altered its plans to include a reduced internal floor area of 79.86 sqm, a larger verandah, different window configurations, and an additional car bay.
However, the home owners were not aware of the altered plans until the granny flat was built five months later.
The board found that Prestige’s conduct was negligent as it failed to inform the owners that the revised R-Code application involved significant structural changes.
However, the Board noted Prestige had reached a conciliation agreement with the home owners.
The company additionally cooperated with the investigation, had no prior building enforcement matters and advised that it had since improved client communication processes.
Building commissioner Phil Payne said the case underscored the importance of builders fulfilling their responsibilities to home owners.
“The builder was solely responsible for notifying the owners about the changes and its conduct was inconsistent with contractual obligations and accepted industry standards,” Payne said.
“Contracts and any amendments must be signed by all parties and verbal agreements must be documented in writing.”
According to Fundd data from last year, rental prices for two-bedroom granny flats in Sydney and Melbourne have risen to about $350 to $600 a week, with potential annual gross income ranging from $18,000 to $36,000.
Further, Domain’s 2025 End-of-year-wrap report found that “granny flat” and “dual” surged to the fourth and fifth most commonly searched terms nationally, while regional markets also saw the term “duplex” trend.
According to Maple CEO Beau Arfi, demand for ready-to-go granny flat kits was increasing, with investors opting for dual-income strategies rather than just buy-and-hold single dwellings.
He said granny flats were no longer a niche idea and were becoming core infrastructure for the next stage of residential supply.
“People are sitting on goldmines in their own backyards,” he concluded.