Planning and Building Permits Required To Build An Accessory Dwelling in South San Francisco

At New Avenue we have paid over 30 different types of permits to get residential projects approved.  These are “normal” projects too such as additions, remodels, restorations, accessory dwellings accessory structures and custom homes.

One of the architects who is a partner at New Avenue’s recently completed in depth research for the permits required for a new Accessory Dwelling in South San Francisco, CA.

This is a great starting point if you are researching.  Most people have never heard of all these permit requirements.  We guarantee your project will be different though.

Here are our findings:

Discussed the project with Patricia Cotla, city planner, to discuss the planner req. for city of South San Francisco. We also had communications with the fire Marshall (Luis DaSilva – 650.829.3950) regarding the fire sprinkler requirements. Please note: Per city of South San Francisco Municipal Code, addition of new kitchen constitutes dwelling unit.

Q: What is the zoning district?

A: RL-8 Low Density Residential

Q: What is the allowable coverage? How is it measured

A: 50% of lot. Lot coverage is the ratio of the total footprint area of all principal and accessory structures, including garages, carports, covered patios, and roofed porches divided by the area of the parcel. Unenclosed and unroofed decks, uncovered patio slab, porches, landings, balconies and stairways less than 30 inches in height; Eaves and roof overhangs projecting up to two-and-a-half feet from a wall; Trellises and similar structures that have roofs that are at least 50 percent open to the sky through with uniformly distributed openings are to be excluded.


Q: Is there a floor-area ratio (FAR) between the Main Home and the Second Unit? What is it?

A: For detached ADU maximum size is 640 s.f. For attached structures, the maximum size allowed is 30% of main dwelling.

Q: What is the maximum allowed size for the Second Unit?

A: 640 sq. ft.

Q: Do chimneys, window boxes, and/or bay windows count toward the square footage of the Second Unit?

A: No

Q: Do other structures count toward the existing footprint? What are they?

A: All principal and accessory structures, including garages, carports, covered patios, and roofed porches count toward footprint.

Q: Does the basement and/or attic count toward the floor area of the Main Home?

A: Only if it has habitable floor space

Q: Can the Second Unit have two floors?

A: Yes

Q: Can the Second Unit have a loft, mezzanine, open storage, closed storage, and/or attic?

A: Yes. However it is limited by the maximum building height.

Q: Can the loft be habitable space?

A: Yes but it will count towards the maximum allowable area.

Q: Can the Second Unit have a basement, workspace, or other area? Do they count toward square footage?

A: Yes but it will count towards the maximum allowable area.

Q: What landscaping requirements and exceptions are there

A: Required for front and street-facing side setbacks, except for areas used for exit and entry, but no requirements in rear. No additional requirements for the ADU.

Q: Is this a liquefaction zone?

A: No

Q: Is this a fire zone?

A: No

Q: Is this a flood zone?

A: No

Q: Is this an environmental zone?

A: No

Setbacks and Dimensions

Q: What is the front setback?

A: 15′-0″

Q: What are the side setbacks?

A: 5′-0″

Q: What is the rear setback?

A: 20′-0″

Q: What are the required setbacks to the Main Home?

A: 10′-0″ separation

Q: What are any other required setbacks? Special setbacks may be needed for creeks, power lines, key or corner lots, etc.

A: None, there are no creeks, power lines or easements on this parcel

Q: Are there any setback exceptions?

A: No

Q: Can the Second Unit be connected to the Main Home? If not, how far apart do they have to be?

A: Yes, but if detached 10′-0″ separation required.

Q: Can we continue a wall of an existing structure within a setback? Is there a maximum length for walls

A: No

Q: What is the maximum height limit? Is there a max average height limit? Can we match the height of the existing house?

A: The average maximum height between the floor slab (concrete slab on grade) and ridge pole is limited to 12′-0″. If raised floor construction (floor joists with crawlspace) is used, the maximum height limit may be increased to 15′-0″.


Q: Do we measure from the sidewalk, the property line, or from somewhere else?

A: Measured from property line/edge of side walk

Q: How many parking spaces are required for the Main Home? Sizes? Do they need to be covered? What configuration or access must they have?

A: additional parking required, not in tandem. Planning deems requirements for proposed second dwelling fulfilled by existing conditions.

Q: How many more new spaces are required for the property? Sizes? Do they need to be covered? What configuration or access must they have? Do they require a border around them?

A: None.

Q: Is there a turning radius or other parking rule to test?

A: No

Enter any additional notes.

Also see “Additional information for Planning Research Form #38” for additional fees associated with building a new dwelling unit. Survey is not required by Planning Dept. However, it could be required by the engineering dept. We would recommend getting one now just in case.

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