Diabetes Otago president Mervyn Wilson said the two charities jointly owned the building, which the Heart Foundation left a few weeks ago.
The foundation's new Hanover St base is to be officially opened today.
Although the building needed strengthening, costing about $250,000, it was safe to occupy, and work was not needed immediately, Mr Wilson said.
The engineer's assessment was prompted by a crack that appeared late last year. Both parties initially decided to leave, but Diabetes Otago had been unable to secure a premises sufficiently close to Dunedin Hospital. Being close to the hospital was crucial.
Mr Wilson said Diabetes Otago wanted to investigate its options, including a long-term plan to fund the strengthening work, and buying the foundation's share.
However, it needed a reasonable timeframe to decide the best way forward, something he hoped to secure today when he meets Auckland-based Heart Foundation chief executive Tony Duncan, who is in Dunedin for the official opening.
The foundation wanted the building sold soon to realise its equity, Mr Wilson said.
In any "divorce", communication was vital, and this had been somewhat lacking, Mr Wilson said. The two charities bought the building together to co-occupy in 1988.
Heart Foundation health promotion co-ordinator Jo Arthur said the Frederick St building would have no insurance cover in the event of an earthquake.
Because of the structural and insurance issues, the Heart Foundation found new premises, and its chief executive would work through a process with Diabetes Otago, she said.