San Francisco's Planning Department and the Board of Supervisors have designated several different types of zones for the City. These range from strictly "Residential Districts" to "Heavy Commercial Districts." Zoning codes for each of these areas specify or limit certain aspects of land use, such as parking requirements, occupancy limitations and allowable building heights.
Why should zoning be important to you as a homeowner? Very simply, zoning laws limit what you may or may not do with your property. In addition, because these laws specify what other residents of your district are permitted to do — such as build additional units to their homes or operate certain types of businesses — zoning designations can affect your property value and your quality of life. Plus, from a larger political point of view, zoning laws lay at the root of the City's housing crisis. For example, lifting restrictions on construction of higher-density condominiums in certain areas could help offset San Francisco's shortage of affordable ownership housing.
If you are not yet a homeowner but are thinking of buying, you should keep in mind that certain zoning restrictions may apply to a property. You should not assume that a current use is necessarily authorized or that you may make any modifications as desired. For instance, you might want to add an in-law unit over a garage, but doing so may place you in violation of zoning laws. If you're at the point of purchasing a home, the seller should provide you with any public reports concerning restrictions on the property such as special-use permits, variances, occupancy limitations and/or other zoning restrictions. However, it is your responsibility to contact the Planning Department's Zoning Administrator to verify the accuracy of any reports, confirm any authorized use, find out if the property is subject to any special use permits, and more.