National and the government have worked together to design new housing density rules that would allow three homes three storeys tall without a consent.

In a rare show of bipartisanship, Labour government ministers Megan Woods and David Parker shared the podium with National's leader Judith Collins and housing spokesperson Nicola Willis to announce the changes at midday.

The parties worked together on a new Bill to amend the Resource Management Act, making it easier to build houses.

It includes new intensification rules allowing up to three homes three storeys high to be built on most sites without resource consent, a change from district plans which typically only allow for one home of up to two storeys.

"There will be exemptions in the medium density rules in areas where intensification is inappropriate, such as where there is a high risk of natural hazards, or a site has heritage value," Parker said.

"So more homes can be built quicker, in most cases the MDRS will have immediate legal effect as soon as plans are publicly notified by councils by August 2022."

The government said modelling by PwC predicted the new rules were predicted to result in about 48,200 to 105,500 new homes being built in the next five to eight years.

Collins said the Bill was the result of work between the two parties over the past year, begun after the government saw merit in National's draft bill presented in April.

"They welcomed National's contribution to further development of policy to allow a serious uplift in new housing in urban areas ... National has appreciated the opportunity to contribute constructively to this development process."

Local government plans to change housing rules have spurred debate Wellington and Auckland over protection for heritage areas and which suburbs to open up to higher-density zoning.

The bill would also bring the National Policy Statement on Urban Development forward by one year, so councils in metropolitan areas would need intensification policies in place by August 2023.