Half of Sydney's suburbs – and not the ones you might expect – face a significant oversupply of housing according to a national property market analyst.

"The official data leaves us in no doubt that several pockets of Sydney will become oversupplied," said Propertyology market analyst, and buyers agent, Simon Pressley.

​"Sydney's economy is likely to remain strong, providing a solid floor under its property market generally. But that's not to say that there aren't a few cracks. Several pockets may well see price declines," Pressley said.

Several pockets of Sydney housing may see price declines. Michele Mossop

The pockets include the former local government areas of Hornsby and The Hills in the north; Lane Cove, Ryde and Willoughby on the lower North Shore, Rockdale and Hurstville in the south, Canterbury and Bankstown in the south-west, Camden, Campbelltown and Liverpool in the far south-west, Ashfield, Burwood and Strathfield in the inner west and Penrith in the outer west.

The analysis is based on the ramp up in housing approvals, which have jumped from around 22,500 a year in the first decade of the century to 51,000 in 2015.