Auckland is building less than half the homes it needs each year to start easing the city's housing shortage, new figures show.
Auckland Council data shows 6260 homes were completed in 2016, 1000 fewer than the number it previously made public.
RNZ has obtained six months of refined data from the council, which has been looking for a more accurate way to determine the number of homes actually built.
The latest data for the year ending in May, show the annual rate has spiked from the previous month to reach 6827 - still a long way short of the 14,000 needed each and every year for the next decade.
Independent housing strategist Leonie Freeman, who has organised a Housing Summit in Auckland tomorrow, said the lower figures we worrying in a market that appeared to be slowing.
"The trajectory of where everything is going is nowhere in that direction, and when you think about where we are in the property cycle and the potential changes, then I would project the number over the new few years would decrease," she said.
Traditionally the only measure of new home building activity had been the monthly data from Statistics New Zealand, showing the number of building consents granted for future projects.
But until recently, no one has been able to track how many of those consents were built.
The Auckland Council has been trying to get more accurate data from its own resources, on building completions, and early this year put the 2016 figure at 7200.
The latest lower figures are now based on the number of Code Compliance Certificates issued, the absolute final sign-off before a property can be sold and occupied.
Ms Freeman was last year unsuccessful in getting a multi-sector organisation established to come up with solutions and make sure house-building targets are met.
"I still believe that the only way we are going to solve this is connecting the dots, and get people focused on setting some targets, and figuring out how to solve them," she said.
The struggle to accurately track how many homes are actually built, can be seen in the gap between the Auckland Council's latest numbers, and new experimental data prepared by Statistics New Zealand.
Earlier in July Statistics released its own version of figures across the country.
For Auckland, using a mix of estimates and hard data, it came up with a figure of 7872 for 2016, versus the council's 6260.
The department said it was still refining its method.