A review of the Defence Force's crumbling estate will redesign plans drawn up in 2016, with the Government committing an additional $400 million to its rejuvenation. 

It will take the total spend to fix buildings and infrastructure across the military's nine New Zealand camps and bases to $2.1 billion out to 2030. The money will come from the $20b investment announced in June, boosting New Zealand's wider defence capability. 

Defence Minister Ron Mark made the announcement while on a visit to Trentham military camp. He said a long-term review was important, alongside continued investment to stop infrastructure becoming more dilapidated. 

"The 81,000 hectare Defence estate is at a crossroads; much of it is run down, and outdated. It needs to be improved in order to gain, train and retain our service people, now and into the future.

"We need to be smart with our investment into the estate. So it makes sense for us to take stock of what we have, and look at what we will need in the year 2070.

"This is particularly important with the new capabilities identified in the Defence Capability Plan 2019, due to come online in the next decade," Mark said.

But National Party defence spokesman Mark Mitchell said an additional review was a waste of time. 

"What needs to be fixed or redeveloped is known in extremely granular detail already, so this review is nothing but a costly time-wasting exercise.

"Defence Force morale was at an all-time high and attrition rates were at an all-time low under National because we took Defence seriously. Both will suffer if real spending on bringing the Defence Estate up to standard doesn't begin in earnest very soon," he said. 

"While this Government has sat on its hands for the last 20 months awaiting four reviews into Defence policy, procurement and capabilities, our Defence Estate has languished."

NZDF was responsible for the third-largest area of Crown land and managed 58 sites, including nine camps and bases, across the country.

A business case released on Thursday alongside the review terms argued the estate was old and outdated, "with a large proportion dating back to World War II".

About 78 per cent of it had less than 30 years remaining in useful life with a replacement cost of over $3.2 billion. Of this, 15 per cent had less than 10 years remaining life with a replacement cost of more than $600 million.

Mark said a number of changing demands and priorities on the Defence Force, domestically and overseas, meant a review needed to assess requirements out to 2070, "so we can begin to plan a way to get there".

The previous government created the Defence Estate Regeneration Plan to manage the estate with an investment of $1.7 billion to 2030. The review will essentially overtake much of that work, but some projects remain underway.

The airforce base at Whenuapai was set for a new gymnasium, new fencing and changes to the facilities that had supported the old fleet of P3 Orion aircraft. But their replacement with Boeing P8-A Poseidons - which would be based at Ohakea - would require a certain amount of reconfiguration at both bases. 

Among a range of upgrades planned for Devonport Naval Base was new accommodation and new offices, meeting rooms and secure spaces for NZDF lodger units.

Ohakea would get a new hangar for the Poseidons and upgrades to its wastewater management system and taxiways. Planning work was also scheduled to begin on a Base HQ building and a physiotherapy and medical facility.

Waiouru would see a change in focus and function, acting as a mountain training base. Plans for upgrades there included a base headquarters communications and control centre. 

Units from around the country would congregate at Waiouru and prepare to deploy on operations from there. Meanwhile, Linton Army camp was set to receive major upgrades to make it one of two logistics hubs, along with Burnham Military Camp. 

"The review, plan and continued investment in the defence estate will result in better working, training and living conditions for all personnel," said Mark.

The review was due to be completed by 30 September 2020. 

A Joint Ministerial Group would oversee it, led by the Minister of Defence and including the Minister of Finance, Minister of Regional Economic Development, Minister for Infrastructure and the Minister for Housing and the Minister for Urban Development.