These people got lucky. In this case the stove connector or flue was probably improperly installed, possibly an unlisted chimney flue pipe, connector or pass through or one of these parts not meeting the necessary clearance to the combustible wall. Nine times out of ten this type of fire is preventable with a proper chimney cleaning and inspection.

— Firefighters suspect a stovepipe inside a wall of a house south of Nampa caught the wall on fire Sunday.

John Lindberg, a captain for the Nampa Fire Department, said he suspects the inside of the wall was smoldering for some time before smoke was visible. The people who live in the home on Ruth Lane smelled smoke early in the day, he said. But the fire wasn’t reported until 1:23, a Nampa dispatcher said.

The fire worked its way from into the house’s second floor, Lindberg said. It only took a few minutes to extinguish once firefighters showed up and opened the wall to battle it, he said. The damage to the house wasn’t too bad, Lindberg said.

http://www.idahostatesman.com/2015/01/25/3610426/house-fire-south-of-nampa-quickly.html