Princes Wharf's apartment and office occupants have put aside almost $1 million to deal with potential structural problems on the wharf below the waterline.

An operating expense schedule shows $10 million-plus bills in just three years, including an "underwater maintenance fund" of $980,000.

Experts have questioned the structural integrity of buildings on the wharf, developed from the old cargo sheds. The worst problems are believed to involve Shed 24, which houses apartments, shops and offices.

The Weekend Herald reported the Hilton Auckland, in Shed 21, has closed rooms on six floors to fix leaks.

The buildings stand in a high wind zone and are being buffeted by salt spray and movement when big cruise ships dock alongside, particularly at the height of the cruise ship season.

The operating expense schedule shows consolidated properties, including the commercial premises, with $1.6 million cleaning costs over three years, repair/maintenance bills of $1.1 million, an underwater maintenance fund of $980,000, security costs of $1.5 million and management charges of $1.2 million.

Owners of about 240 apartments face a repairs/maintenance bill of $850,000, underwater maintenance fund $450,000, cleaning $560,000, management charges of $630,000 and security $450,000.

Disgruntled owners of defective, leaky apartments want to keep problems quiet and many apartments on the wharf are either for sale or for rent.

Hamish Duke, a City Sales agent who has sold 50 wharf apartments, said the operating expenses were not exorbitant. "That's reasonable sums compared to the Viaduct stock."

Princes Wharf property ground/wharf rents were up just 10 per cent on review lately, which was reasonable, and were on average $6000 annually for a one-bedroom unit, undercutting the $10,000 being charged nearby at The Point.

The $1.8 million underwater maintenance fund charge was the owners' contribution to wharf repairs and was not an ongoing charge, Mr Duke said.

Owners of approximately 90 units in Shed 24 owners were paying almost $1 million or $10,000 each, levied in three instalments, to fix problems with leaks on decks, he said.

"It's not as major as it seems," Mr Duke said, adding that $1 million-plus could be achieved on unit resales.

The Weekend Herald published findings of a report raising serious issues with Shed 24 and the Hilton Auckland.

Architect John Sinclair wrote the report for Dockland Holdings, which has a big stake on the wharf.

"In my inspections I did not see any evidence of structural degradation," Mr Sinclair wrote of Shed 24.

"I have assumed that the structures were designed in accordance with the regulatory requirements, property checked, consented, professionally supervised, inspected and certified as fully complying."

Mr Sinclair blamed Shed 24's leaks on defective cladding, failure of the exterior waterproofing system, aluminium joinery and deck surface waterproofing. He said timber could be secretly rotting.