Enlarging buildings by raising them and adding a new first floor was common at one time. Many cottages throughout San Francisco were originally one to 1.5 stories in height. These modest cottages were set on wood pilings instead of solid foundations. Buildings that must be raised for seismic retrofitting or to install a foundation will be approved.
However, despite historic precedents, raising buildings designated as historic resources may not be considered appropriate and all proposals will be reviewed on a case-by-case basis.
The CityStructure Report tells you in which historical category falls a property and if you could build additions to the existing building.