An independent housing review will give the Government an indication of the areas it needs to be targeting, Prime Minister Jacinda Ardern says.

Housing and Urban Development Minister Phil Twyford has commissioned a panel of three to provide an "independent stocktake of the housing crisis".

Economist Shamubeel Eaqub, professor Philippa Howden-Chapman and Salvation Army policy analyst Alan Johnson were to carry out the review by Christmas.

National housing spokesman Michael Woodhouse questioned why Twyford needed to set up a committee to tell him what he already knew.

"He has claimed for the last five years that he's got all the answers, that he knows what the problem is, that he had a solution ready to go," Woodhouse said on The AM Show.

The government's freshly announced stocktake of housing is being dismissed as nothing more than smoke and mirrors. The National Party says the government already has this information at its fingertips, so it is a waste of time for the Housing Minister Phil Twyford to commission a report into it. But Mr Twyford says it is time the public knew the truth.

Ardern told The AM Show one of the aims of the review was "transparency".

"What we want to do in a short sharp burst is bring in some experts who have real knowledge around housing quality, around social housing, around rental and home ownership to help us give the public a sense of what we'll have to face over the next three years."

Those experts - who had struggled to get access to the data before - were being given that access so they could produce a report about all the areas with evidence about what needed to be targeted, Ardern said.

"They're going to give us a starting point. They're going to demonstrate to us the areas that we really need to make sure we're targeting. Of course we have a sense of that."

It was an example where the new Government had found the issues were larger than it had predicted. For instance, there were predictions that without Labour's KiwiBuild programme construction activity would have started falling away.

For now, the Government was sticking with intentions of building at least 1000 state houses a year but had asked Housing New Zealand what was possible.

There were fiscal constraints, Ardern said. After cancelling tax cuts, the Government had to ensure middle income earners were getting some respite.

Twyford has said there is a shortfall of 71,000 houses across the country, but Woodhouse said he was "overreaching" with that figure.

"If there was a housing supply crisis the rate of inflation in housing would not be under 3 per cent, rents would not be dropping in Christchurch," Woodhouse said. The 71,000 figure did not tie in with the reality, he said.

he previous government had brought house price inflation under control with its initiatives. Because of those initiative 102,000 houses were ready to be built. Twyford should do more than that, Woodhouse said.

While he asserted there was no crisis, he accepted there was a lack of houses in the low cost bracket.