"There are literally hundreds and, if you take into account apartment complexes, thousands of home owners who have had applications ruled out on this built-date issue,'' he said.
The Osbornes' Remuera home was built in 1996, with code compliance certificates issued in February and April the following year.
The couple bought the house in April 1997, and discovered leaking later that year. Failed repair attempts were carried out between July 1997 and 2002.
A claim was filed with the Tribunal in February 2007, but only matters related to the later repairs were deemed eligible.
The couple have now spent $500,000 on fully repairing the home, where they still live.
``It's a very unfortunate situation for the Osbornes, and it's been a very long and hard battle,'' Mr Rainey said.
``They've suffered dreadfully as a result, and we just hope we'll be able to get them their day in court, and hopefully some money back.''
So far the courts have upheld the Tribunal's interpretation of the law, with today's (Wed's) decision the first in the Osbornes' favour.
In a judicial review in 2011, the High Court agreed the clock starts when physical building work ends, rather than when approval is issued.
Leave for a further appeal was declined by the Court of Appeal in May last year, but today the Supreme Court granted leave to appeal against the interpretation of the 10-year limit.
The appeal will also consider whether the Osbornes can seek any further remedy from the Tribunal, as under the Weathertight Homes Resolution Service Act a decision of the High Court is considered the final determination of the Tribunal.
Mr Rainey hoped the appeal would be heard by the Supreme Court within the next few months. If successful on both questions, it would mean the Osbornes' original claim could then be heard by the Weathertight Homes Tribunal.
Auckland Council were unable to respond to questions by deadline.
