The blaze brought firefighters to a two-story, single-family house at 1533 Lodi Ave. at 3:54 a.m. It appears the flames originated in the garage of the home and then spread to the second floor and attic, San Mateo Fire Department Battalion Chief Mike Borean said.
The fire also affected the outside, attic area and second floor of a neighboring two-story home at 1541 Lodi Ave.
Firefighters from several agencies, including the Foster City, Belmont-San Carlos and Central County fire departments, responded to the blaze and the flames were declared under control at about 4:20 a.m., according to Borean.
He said that the effort was hindered because the homes had undergone construction and there was plywood in unexpected areas.
Thirteen of the displaced residents were being accommodated by the American Red Cross, according to Borean.
The blaze caused an estimated $250,000 in damage to the primary fire building and $150,000 to the neighboring building.
Borean said it appears the fire started because of an electrical problem in the garage of the 1533 Lodi Ave. home.
There was no reports of injuries.
Firefighters were continuing to clear the area at about 8 a.m., but some officials planned to remain through part of the morning to help residents retrieve belongings, Borean said.