A couple had a lucky escape after waking up to find the lounge of their house full of smoke, the Isle of Man Fire Service said.
Fire crews were called to reports of the fire in Princess Street, Douglas, on Monday morning.
The source was a slow burning fire in the joist under the floorboards, which had been caused by a cracked hearth in the fireplace.
Crews had to cut through the floor to remove the burning material.
A spokesman for Isle of Man Fire and Rescue Service said the couple had a "lucky escape".
"The fire had been slow burning and had gone undetected for some time which had resulted in it almost burning completely through the floor joist and burning the underneath of the floor boards," he said.
"Luckily for the couple some of the smoke had worked its way into the lounge allowing the fire to be detected.
"This was very fortunate for the couple as they were due to leave the Island that afternoon to go on holiday.
"There could have been serious consequences had the fire gone undetected for any longer."