The neighbouring unit was not damaged in the fire but, as the two units shared a wall, it would be difficult to just demolish one unit.
The victim, who returned to the unit to collect a few items later that night, was staying with her Tauranga-based daughter, he said.
The victim's friend Damien Bonner told Bay of Plenty Times he was stunned when he drove past on Wednesday morning and saw the state of the unit.
"I was on my way to do some grocery shopping and I thought 'oh no, not [my friend]'. My heart sunk and I was in a bit of a panic until I found out she was okay," he said.
"I feel so sorry for her. I have known [my friend] for just under a year but she's been a good friend and she's such a good natured lovely lady who wouldn't do harm to anyone.
"[My friend] loved this little house and she has pretty much lost everything, including all her precious knick knacks that she's been collecting for quite a few years," he said.
Mr Bonner was urging people to dig deep to help her get back on her feet and hoped someone might launch a Givealittle page.
He said his friend would need lots of support.
"I can offer her a place to stay if she needs it, but if any one can give her a little bit of money to help her get back on feet, that would be fantastic," he said.
Mr Sabin said this was the second fireplace-related blaze in two days after a sleepout in Carmichael Rd, Bethlehem was also destroyed on Monday.
"Two fireplace-related fires in two nights, which have turned the lives of the tenants upside down, is not a good record," he said.
Some key fire safety advice
Never leave an open fire unattended
Ensure fireplaces are regularly maintained
Use fire guards and safely dispose of embers
Working smoke alarms save lives