Police confirmed they were called to Tarewa Rd just before noon last Friday and found a woman's body in the advanced stages of decomposition.
The board was asked when it last visited Henry but chief executive Nick Chamberlain said the woman was "living largely independently not requiring constant checks from the mental health service".
Donna said that she and other residents at the units were struggling with the thought their neighbour was lying dead in her home and no one noticed.
"It's very emotional for us to process and I wouldn't like to see it happen again.
"I hadn't seen [Carolyn] for three or four weeks. She wasn't sitting outside smoking, or being picked up to go shopping, and I thought she must have gone into respite care," she told RNZ.
Chamberlain said other residents of the units had been offered support.
"On the same day she was discovered, all the residents were visited by mental health staff offering support and each of their community support workers were also informed. One resident was offered and accepted respite," he said.
A service for Henry was held at the Maunu Crematorium Chapel yesterday. She is survived by her mother Dianne who lives in Australia. Her partner died several years ago.
The Fountain Lodge Apartments are owned by Dumas Enterprises, which provides low-cost housing to people who experience poor mental health or have had a traumatic brain injury.
The company is owned by similar directors to Goodwood Park Healthcare, which rents an office on the Tarewa Rd site, and supports people who have suffered a brain injury or serious injury, a service that is funded by ACC.
Goodwood Park Healthcare general manager Kenny Paton said the two companies are separate, and although Goodwood provided healthcare services, it is not funded or contracted to provide any services or support individuals staying in the apartments.
"In relation to the tragic events that have unfolded, the directors and management of both Dumas Enterprises and Goodwood Park Healthcare can only offer their condolences to the family."