Wellington philanthropist Mark Dunajtschik, right, with Capital & Coast DHB chairman Andrew Blair as they sign the deal for Dunajtschik to donate a $50 million children's hospital.

Wellington is to get a new $50 million children's hospital, paid for by millionaire property developer Mark Dunajtschik.

The philanthropist will pay for, build and donate the hospital to Capital & Coast District Health Board (CCDHB), which will name it after him.

"I want to build the hospital, not just write out the cheque," he said.

ROBERT KITCHIN/STUFF Mark Dunajtschik, watched by Prime Minister Bill English and Health Minister Jonathan Coleman, announces his gift on Monday morning.

The present children's hospital, which is almost 30 years old, has been deemed not fit for purpose.

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Dunajtschik will build the new hospital with property partner Grant Corleison​ because they believe they can build more at a cheaper cost than government departments can.

ROBERT KITCHIN/STUFF Dunajtschik will pay for and build the hospital, saying he can do it cheaper than any government department.

"Most benefactors write out a cheque, but in this case, that wouldn't get nearly as much done for the money. I can use my skill as a builder and developer to get the maximum value out of the $50m I'm donating for our children."

His philosophy was that people blessed with a sound mind and body can look after themselves, but those born with or suffering illness and disability needed support.

The building will be on the northern end of the hospital campus, in front of the Riddiford building, and will have a link bridge connecting it to the existing hospital. Doctors and nurses will be actively involved in designing it.

ROBERT KITCHIN/STUFF People blessed with a sound mind and body can look after themselves, but those born with or suffering illness and disability need support, Dunajtschik says.

Dunajtschik said it would take about 18 months to build after resource consent had been granted, and he expected that would be within six months.

CCDHB chief executive Debbie Chin said the health board had been working on a long-term plan for child health services, which included a new hospital, but building wasn't going to start for several years.

"Mr Dunajtschik's generosity means we'll get the hospital much sooner."

Health Minister Jonathan Coleman said funding that would have been used for a hospital would be reallocated to other areas in the health budget.

"Mr Dunajtschik is a man of action and wants to do it now, and that is totally appropriate, so we are not going to muck around."

There would be about $7.5m to $12m in extra costs, for things such as demolition of the old building, which the Government would work with the DHB to help cover, he said.

Gifts did not attract a capital charge, but there would also be a deprecation charge of about $2.4m, and the DHB might need some extra funding to help with it, he said.

Prime Minister Bill English said the donation was quite unexpected and extremely generous.

"This is someone with a big heart, helping people who cannot help themselves. He has supported causes for decades now without any recognition. We are grateful for his generosity."

This was the first time he knew of in which anyone had donated an entire hospital.

The current hospital was the first of its kind in New Zealand, and each year more than 30,000 children passed through its doors, including the 4000 or so babies born there annually.

The DHB said it was cramped, with inadequate clinical areas, no dedicated areas for family and had insufficient isolation facilities.

Existing child hospital and outpatient services – currently housed separately – would be merged in the new hospital, which would maintain current staffing levels.

"This amazingly generous offer will have such a big impact on the children we look after, their families and our staff," CCDHB chairman Andrew Blair said.

Wellington Deputy Mayor Paul Eagle said it was an outstanding contribution by an outstanding individual.

It was a huge gesture of generosity for the city and region. "The DHB is one of the most efficient in the country, despite being underfunded, and this will help it deliver much-needed services for young people."

Wellington Chamber of Commerce chief executive John Milford said Dunajtschik deserved the highest praise.

"Mark is giving back to the Wellington community that he and his business have been a part of for many years. This is a truly generous contribution and will be an enduring legacy."

BY THE NUMBERS:

* 18 months to build

* 7000 square metres, over three floors

* 50 inpatient hospital beds, as well as social and family areas

* Outpatient consultation rooms

* An education and research centre, integrated with Otago University

* Staff and administration areas