Former Dunedin resident Frank Buddingh and his wife Nina Arron, both of New York, said their ''quest for preservation'' of this historic, category 1-listed building started in about 1993, when they bought it.
In 2012, they gained a $60,000 grant from the Historic Places Trust to help protect the roof, but the grant was not uplifted.
Since 2012, the couple had initially divided their time between the United States and New Zealand but, over the past few years, they had spent more time in the US due to work commitments, ''my wife as an urban planner and I as an arboricultural tree consultant'', Mr Buddingh said.
They hoped that selling the building would enable the ''restoration process'' to ''gain new momentum to preserve this building'', he said.
The 240sq m building, on a 2035sq m site on the northern side of Colonsay St, overlooks the township's main street.
Throughout their ownership, whether they would ''permanently live there or otherwise'', their main aim concerning the school and hall complex was to ''make it accessible'', and at least partially available to the community.
''We strongly believe that this part of New Zealand history should not vanish.''
The building could be used as a ''dwelling/art studio, a reception or intimate concert space, a museum space''.
It had also served briefly as a local cinema.
They had received an extension from Heritage New Zealand, but in the end the couple had informed HNZ they could not get ''the right team'' together to start work before the required deadline.
He said they they had "worked hard to gather quotes from builders who are specialised in historic building restoration'' and trying to work out an acceptable work schedule for the roof reconditioning.
"We were not able to find the right match and also found it increasingly complicated to ensure quality control over the work once the roof restoration would start."
"Since the grant was a time-bound grant we asked for and were granted an extension, for the grant, but in the end we informed Heritage New Zealand that we could not get the right team together to start the works before the required deadline."
"We have, over the years laid the basis for stabilisation and drainage of the foundation with much appreciated help and assistance from HNZ.
"Over the ensuing years we have had our unfortunate issues with specialists starting work on the building. One architect passed away while working on the plans and we had an agreement to work with a restoration builder, who sadly drowned at sea,'' he said.
Nevertheless, he and his wife did preserve the foundation, did work on down piping and had an archaeological dig that resulted in restoring the front grounds of the building, which was the original playground, he said.
The hall is one of only about three known surviving public buildings designed in timber by Lawson, and his only known building for the Catholic Church.
The Heritage New Zealand internet site said the large wooden building had been officially opened by Bishop Patrick Moran on March 17, 1872, and used as both a church and school for 20 years, becoming, in the 1870s, the largest school in the diocese.
The elegantly proportioned design was a rare example of school architecture, and was of ''outstanding architectural significance''.
