"The steady rise in vacancy rates through 2014 suggests that an excess of rental stock is emerging within inner Brisbane," the report says.

"Moreover, preliminary data suggests unit prices may have declined, as the record level of apartment completions in 2015-16 creates increased competition and has a negative impact on resale prices."

But a massive crash in prices is unlikely because property owners will still be able to comfortably service their mortgages at low interest rates, BIS Shrapnel senior manager Angie Zigomanis said.

"While there won't be forced sales, [these conditions] should keep prices at no growth," he said.

"Anyone who bought off the plan in the last year or two is unlikely to get a gain.

"Something needs to change in southeast Queensland, in terms of migration and economics, to change the vacancy situation. Otherwise we'll need a big change of preferences to live in the city."

And this is exactly the likely outcome especially with good developments, Metro Property Development, which has a 30 per cent market share of the apartment market in Brisbane, said.

"Apartments that provide amenities, facilities to the rental market will continue to have demand," Metro chief executive Luke Hartman said.


"Those in older apartments will move into new apartments."

In contrast to BIS Shrapnel's findings, Metro's six completed inner-city towers – consisting of 1212 apartments – report a vacancy rate of only 0.5 per cent.

There are twice as many inquiries for Metro rental stock, Mr Hartman added.

"This demonstrates the danger in applying a broad-brush approach to market conditions that are far more nuanced and segmented than the BIS Shrapnel report accounts for," he said.

"In particular, quality and well-located new stock from established developers will out-perform the average ... inexperienced developers."

BIS Shrapnel also said Brisbane's apartment supply will reach record levels by 2017 and 2018, based on current approvals.

"Due to rising construction costs and tightening finance provisions, it is to be questioned how many of these forecast apartments will be completed?" Mr Hartman said.