A couple fled their burning home in Brownhills after smelling smoke, before the devastating blaze ripped through the upstairs of the house within minutes.
The pair, in their 30s, escaped unhurt from the mid-terraced property.
Fire crews from Walsall and Sutton Coldfield were called to the house in Third Avenue, and back-up was sent from Fallings Park and Wednesbury to help deal with the threat of the blaze spreading to neighbouring homes. They identified a rear bedroom as the source of the fire.
They doused the roof, which was becoming engulfed by the flames, and room with jets.
Watch commander John Horton said the fire was brought rapidly under control, preventing any damage to other homes but the upstairs was "totally destroyed", he said.
"When we arrived, flames were engulfing the first floor and going into the roof space," Mr Horton added.
"The rear bedroom was severely affected and, with it being a mid-terrace, there was a real danger it would spread to other properties. That was our main concern.
"We managed to push the fire back so it didn't go into the other side of the house and the neighbours' home.
"Luckily we got it under control really quickly, within 20 minutes. But the first floor has been totally destroyed."
The couple who fled the blaze, which broke out at 7pm on Saturday, are believed to have two young boys who were not at home at the time.
The cause of the fire is being probed by specialist investigators but it is not believed to be suspicious, Mr Horton added.
"We think it's either accidental or electrical," he said.
The downstairs of the property was not damaged.
Part of Third Avenue was cordoned off while the 20 firefighters battled the blaze. It reopened at 9pm.
Crews returned to the yesterday for safety checks.