The gap between Sydney and Brisbane house prices is starting to bear fruit for developers and vendors in the Queensland capital with dozens of southern buyers taking the plunge.

For about a year the gap between Sydney and Brisbane had been expanding but evidence of southern buyers jumping was not that noticeable by agents and developers.

Now it is.

Listed developers such as Stockland and Mirvac have seen more Sydney buyers for Brisbane artments and private developers such as Tim Gurner have also recorded as much as 40 per cent of investors were from Sydney.

The latest QBE LMI Australian Housing Outlook report prepared by BIS Shrapnel indicates some concerns over a potential oversupply of apartments in Brisbane.

National Property Research Co director Matthew Gross sees the price differential between ­Brisbane and Sydney as more ­influential in driving a property boom than the fundamentals such as the state's unemployment and population growth.

"It's bizarre but it's true," Mr Gross said.