The 911 call from a neighbor at 7:28 a.m. reported smoke coming from the rear of 19 Lower County Road.
The fire was contained to an upstairs apartment over a detached garage, which was unoccupied at the time. It sustained moderate damage.
The garage is owned by Sandy Christian.
The Dennis Fire Department was assisted by the Harwich Fire Department, Dennis Police and reviewed by the Dennis Building Department.
There were no reported injuries.