The cost of the State House sculpture on Auckland’s Queens Wharf blew out to $1.924 million before being scaled back to $1.5 million, papers show.

Documents released under the Official Information Act to the Herald show the original plan was for the project to be finished in the first few months of this year. The completion date was later revised to February 2015 and is now some time beyond that.

Auckland Council announced plans for the sculpture in March last year, to be funded by a $1 million donation from Barfoot & Thompson, marking the company’s 90 years in business.

The documents show the cost of the sculpture – a “scaled version of a Mount Eden state house” by renowned artist Michael Parekowhai – had reached $1.9 million by May 2013.

Images of the sculpture have been shared with councillors but not the public, causing widespread criticism.

In February, Parekowhai told council public art manager Carole Anne Meehan he did not want early concept drawings and photos of a model to be “distributed publicly by anyone attending” a council meeting.

But several images were leaked to the Herald. They show a typical state house with external stairs leading to a platform offering multiple views of the chandelier filling the interior.

They also show a skylight, to allow cruise ship visitors berthing at Queens Wharf to peer inside the brilliantly coloured and intricate glass garden of native birds, flowers and insects inside the house that will glow softly at night.

A council source said if the council wanted to stuff up the sculpture it could not have done a better job.

Today, council chief operating officer Dean Kimpton said there was no fault with the process, but acknowledged it would have been better to have released images earlier.

He said the design had gone through a number of iterations, saying images and construction dates would be made public in mid-December.

“It is what it is. The design process has taken longer … and we have got a great result from Michael [Parekowhai]. I think the public are going to love it. I’m not anticipating a public backlash,” he said.

Asked about ratepayers underwriting up to $500,000 after the cost ballooned above the initial $1 million budget, Mr Kimpton was confident of attracting sponsorship once images, a story to wrap around it and a building deadline were made public.

He confirmed rumours that other suppliers were being considered for the chandelier, including glassworks in the United States and New Zealand, “but it is likely to be constructed in Italy”.

The documents show that Parekowhai was recommended “after careful consideration” as the “only candidate” for the artwork in late November 2012 after a shortlist of 11 potential artists, whose names were redacted, was drawn up.

Said Ms Meehan on November 26, 2012: “This is the right moment for a significant commission for Auckland by him [Parekowhai], as national and international recognition of his work is climbing.” She also recommended moving the sculpture from the cityside of Queens Wharf, a location “sabotaging” its potential, to the water’s edge at the end of the wharf.

The latest breakdown for the $1.5 million project, includes $705,000 for the chandelier, $415,000 for the building, an artist’s fee of $225,000 and $155,000 for a contingency and development costs.

A council document, dated May 15, says the project is a given and will not go out for public consultation in the new 10-year budget.