Christchurch's new acute services building was meant to be finished by July 3, 2018. It is now expected to be finished in the second quarter of next year.

Delays to a Christchurch hospital described as the biggest Government project in the post-quake rebuild are heaping pressure on a health system already stretched to capacity, health board members say.

Contractor CPB started construction on the acute services building in early 2016. Documents released under the Official Information Act (OIA) show the original due date for the $483 million project was July 3, 2018.

That date keeps being pushed back. CPB has filed at least 52 extension of time claims, a report prepared for the May meeting of the Christchurch Hospital Redevelopment Partnership Group (CHRPG) shows.

SUPPLIED An artist's impression of the finished acute services building.

Minutes from the meeting show while there were 600 workers on-site, about 750 would be needed to meet work targets. They also reveal a letter was sent to CPB about its performance. Formal notices have also been issued due to the delays.

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Stuff has approached the company for comment.

IAIN MCGREGOR/STUFF CDHB chief executive David Meates says the delay 'is adding significant pressure' to the Canterbury health system.

Professor John Tookey, a construction expert at AUT, said most major construction contracts would have significant penalty clauses. It was not clear if CPB have been penalised for the delays.

The detail emerged after the Government announced it would look into its procurement policies and make sure agencies abided by them.

Housing Minister Phil Twyford earlier this month said too many agencies followed a least-cost model that left firms with too much risk.

Canterbury District Health Board (CDHB) chief executive David Meates said the board originally planned to move into the acute services building next month. It now plans to do so next September.

"The delay is adding significant pressure to the Canterbury health system which is already operating at, and at times beyond, physical capacity," he said.

Recruitment plans for the acute services building have been slowed down due to the delays, and the CDHB is already planning how to manage demand next winter within its existing facilitates.

Stuff last month revealed occupancy at Christchurch Hospital had hit 100 per cent, with demand attributed to a growing population.

Concerns have already been raised that the acute services building will not be large enough when it opens.

Meates said the CDHB had been advised the building itself would be completed in the second quarter of next year. Board members have described mounting frustration that an exact completion date has not been provided.

CDHB member Aaron Keown said: "People are getting pretty damn annoyed that there's not a completion date this far through. We should have had the locked-in date months ago."

Keown and fellow board member Andy Dickerson said not having a date created uncertainty that impacted on the planning process. Dickerson said it was also an indictment on the CHRPG model, where the CHRPG, not the CDHB, is responsible for the build.

"The migration of services and occupancy of such a large building requires a high degree of planning, and to be this far into the build and still not have a completion date is unacceptable," he said.

Documents released by the Ministry of Health show a June 28 meeting between CHRPG representatives and CPB management resulted in the creation of a workshop to "ensure the project is a success" and is delivered in the "shortest possible timeframes".

A ministry spokeswoman said the acute services building is scheduled to be handed over to the CDHB around the middle of 2019. Delays were due to the "complexity of the build" and the shortage of skilled labour in the "current construction environment".

The ministry did not answer a question about whether the delays had resulted in budget blow-outs on the project.

A previous version of this article quoted a Ministry of Health spokeswoman saying the current budget for the ASB was $463m. The Ministry provided incorrect information. The budget is $483m.