A unit in the charity's Cape Country Accommodation assisted living facility on Cotton Street was gutted by a fire which started on the back deck around 9.30am Thursday.

A Tasmania Fire Service spokesperson on Thursday afternoon said the fire had started accidentally in a stack of logs, and that about $250,000 worth of damage had been done in the blaze.

Vinnies CEO Lara Alexander said that although it was a sad situation for the resident of the damaged unit, it could have been so much worse.

"It is just really unfortunate, but thank god nobody was hurt," Mrs Alexander said.

"Property can be rebuilt and repaired."

She said it was also fortunate that due to the layout of the facility, with the burnt property being a standalone building, the fire had not spread to other units in the facility and other residents were not affected.

The resident of the unit which caught fire was not home at the time, but an elderly woman who lived in the unit downstairs was evacuated by neighbours who noticed the flames.

Neighbour Mike Thompson was one of the first on the scene, and alerted other neighbours to call triple zero while he grabbed a garden hose.

He said facility staff and neighbours acted quickly and "dragged" the woman from the unit as the fire took hold.

"They just got hold of her and dragged her out, mattress and all," Mr Thompson said.

"They just got her out. Right at the time it really started to get going."

Tasmania Police Acting Sergeant Travis van Tholen said the woman was treated for smoke inhalation onsite and did not require hospitalisation.

Mrs Alexander said new accommodation was being arranged for the elderly woman and the tenant of the damaged property.

A career firefighting crew from Burnie attended the blaze alongside volunteer crews from Smithton, Boat Harbour and Wynyard.