The fire was reported at 11:45 p.m. at 2912 21st Ave., located just south of Stern Grove, San Francisco fire Lt. Mindy Talmadge said.
Firefighters arrived at the scene three minutes later and saw thick smoke coming from the home. They battled the blaze for more than an hour before it was extinguished at 12:57 a.m., Talmadge said.
A dog died in the fire but no residents were injured, she said.
The cause of the fire, which was mostly confined to the rear of the home and its basement, is under investigation, but the blaze is not considered suspicious, Talmadge said.