Dunedin Little Sisters of the Poor Sacred Heart Home manager Sr Cecilia McKay said it planned to provide 12 individual accommodation units in building next to its home for 28 aged-care residents overlooking Otago Harbour, in Brockville.
The organisation had raised $4m towards its aim but needed $4m more.
The new facility would be for people who were still able to live alone, but who required some support and some respite from isolation.
Each unit would allow its resident to maintain a personal choice of lifestyle and would be fitted with a full kitchenette, dining and living room, a bedroom and bathroom unit.
There would be a veranda that opened out into the garden or offered the view of the community garden.
The project was first conceived three years ago and since then "daily gifts of donations and collections have been put aside".
But now the Little Sisters would be praying for more.
Fundraising committee member Liz McColl said in Dunedin there were 23,000 people receiving Superannuation; 40% of them have no other income, and about 20% were in rental accommodation
"There are about 5000 people who are potentially the tenants of this facility here," Mrs McColl said.
"So 12 units is fantastic.
"If it was 1200, it would be even better.
"There are two really important factors for people who age well," Mrs McColl said.
"One is exercise, but the most important and the most significant is social connection."
The construction site was blessed on Thursday by Catholic Bishop of Dunedin, Fr Michael Dooley.
"We do make it a rule that we take those who are poor," Sr McKay said.
"And because we go out and we actually ask the public also for help, we feel we’ve got to be transparent in actually living that out and being sincere in taking those who need."
Sr McKay said the first Little Sister, Saint Jeanne Jugan, saw a need in her post-French Revolution days when the elderly were found on the street penniless, without food and lodging.
While society could now provide excellent medical care to the aged, at times the quality of an elderly person’s life was overlooked.
"Essentially our mission has not changed and yet life has become so complicated," Sr McKay said.
In Dunedin, since 1904, the Little Sisters had helped more than 3000 elderly people in need, Sr McKay said.