Russian steel magnate Alexander Abramov's Northland house could be costing $40 million to build, a top real estate expert has estimated.

Graham Wall, the Auckland agent who has sold many of the country's highest-price houses, said it could be New Zealand's most expensive residence, ahead of the Chrisco mansion in Coatesville and ex-Hanover boss Mark Hotchin's much-criticised Paritai Drive mansion.

"I would only be guessing but if you say it's 4000sq m, it could cost as much as $40 million to build. That's everything," he said, including all internal fittings, appliances and electronics.

Mr Wall sold billionaire Peter Thiel a Parnell house and helped the billionaire Sultan of Brunei get $35 million for his Herne Bay properties in Auckland.


Aerial pictures reveal the footprint of the Abramov property at Helena Bay could be 1200sq m - six times the size of a traditional 200sq m Kiwi house.

But the house is multi-level, with grand staircases traversing the place, enjoying extensive eastern and northern views, so the main block could be more than 3000sq m once finished, 15 times larger than the average house.

The job is being run by Coatesville-based Chris Steel. Many other portable structures dot the site, lined with pohutakawa, offering panoramic views and a secluded golden beach.

Secrecy shrouds the enormous Northland project which has hardly featured in the media, despite extensive advertising for workers.

The main u-shaped structure appeared to have an internal courtyard surrounded by extensive water features.

Another separate residence is rising nearer the beach and footings have been dug to link the main building to the seaside structures. Roads snake around the site, hidden down a track about 1km from the road, which is the back route between Whangarei and Russell.

John Beveridge, chief executive of Fletcher Distribution which owns PlaceMakers, said top-end building was extremely active.

"I know in places like Waiheke Island, the Far North and Auckland, there are still big houses and big renovations going on. It has not stopped through the recession."

Ann Midson, media relations adviser to the Whangarei District Council, said her organisation was muzzled from giving details of the job.

"I have followed up with our lawyer to identify whether or not we are able to provide you with the documentation. A resource consent for this project was not required from the council so there is no documentation relating to that," she said.

"A number of building permits were obtained but the applicant has requested confidentiality under section 217 (3) of the Building Act 2004, so we are bound not to release information relating to their building project."