Permit rules for an accessory dwelling in San Francisco (and advice for future ADU owners everywhere)

If you don't plan ahead, the city could make you change your design.

You've spent months (or maybe even years) dreaming about your new accessory dwelling unit. You know exactly what you want and where you want it. And you know just what you're going to do with it. You've got the plans, drawn up by a design professional designer, in hand, and you've hired a contractor to do the construction. You're ready to break ground as soon as your permits come through.

Then, disaster strikes. The city wants a complete re-design. Your plans are not up to code. The ADU is too close to the property line, and it takes up too much space in your yard. The fire sprinklers you chose won't work because of the water pressure, so you need to add a pump. There aren't enough exits, and the windows are too small.

What can you do but start over? It'll cost you thousands in re-design fees, but you can't build an ADU that the city won't approve.

It’s normal for the city to request some changes to your design when you’re applying for permits. Even when you’ve researched the rules, city officials can be a bit unpredictable. You can expect to make some changes to your original plans before beginning construction.

The good news: You can minimize those changes and save yourself thousands of dollars.

While it’s exciting to start planning your new ADU, it’s absolutely imperative that you do your homework first. Here are some things to look into before your design professional begins designing. An even better idea: Have a professional look into them for you.

Here's what to look into before you start planning.

Here are some of the most important guidelines in sf-ADU, a guide sponsored by the San Francisco Planning Department. These guidelines apply specifically to the city of San Francisco, but this list is helpful for future ADU owners anywhere in the United States.

Egress. This refers to a building’s exit routes. There are requirements regarding the number of exits (generally two), their size, and their construction. In most cases, the only exit path cannot be through a garage.

Ceiling height. Ceilings must be at least seven feet high (seven and a half feet for bedrooms and living rooms), but there may be exceptions.

Bicycle storage. Secure bicycle storage may be required. Under certain circumstances, bicycle parking may replace vehicle parking if the bicycle parking is indoors and secure.

Parking. A single ADU usually does not increase the parking requirements because it’s classified as a renovation to an existing property and adding a single ADU doesn’t increase parking requirements by more than one space.

Open space. A certain amount of open space is required on each residential lot. Generally 25 to 45% of the property must remain open, depending on how the property is zoned.

Setbacks. This refers to how close to the property line or an existing structure you can build.

Front yard improvements. The city of San Francisco has requirements for the number of trees a residence must have on its street-facing side. Additional improvements to landscaping may be required when adding an ADU or bringing one up to code.

ADU removal. If you’re removing an ADU or merging it with another structure, you may have to have a public hearing first.

Neighborhood notification. In many cases, adding an ADU requires that neighbors within a certain distance of the project be notified in advance. You will also need to have a pre-application neighborhood meeting.

Pre-application process. A pre-application process my be required before filing your plans with the city.

Historic buildings. Buildings 50 years old and older may need to be evaluated to determine whether your planned modifications will damage an historic resource.

Zoning changes. The city has certain zoning requirements. You may need to file for conditional use or make other special zoning requests with the city if your lot is not zoned appropriately for additional residences.

Fire sprinklers. Fire sprinklers are required in all new residential units. If you’re adding an ADU within an existing home, you may need to add fire sprinklers to the parts of the main home that connect with the ADU and to any escape routes.

Disabled access. Most single-family ADUs will not require disabled access (although making your ADU accessible will mean it can be used by seniors and others with accessibility needs). If adding a unit creates three or more units on the same property, there may be accessibility requirements.

Light and ventilation. All habitable rooms need to have natural light and ventilation. Windows and doors can help meet this requirement. The required area of the windows depends on the size of the room. Bathrooms need exhaust fans.

Seismic upgrades. When adding an ADU to an existing structure, it may be necessary to upgrade the existing building to protect it from earthquake damage. Whether upgrades are mandatory or just encouraged depends on the original design and its compliance with regulations.

Rent control. The San Francisco Rent Board may regulate the amount of rent you can charge and restrict evictions on your property. While many properties are not subject to Rent Board control, it’s a good idea to find out whether a planned ADU will fall under rent control rules.

This doesn’t cover it all. While this list is a great start and gives you an idea of the kinds of things to look for, it doesn’t take the place of doing your own research or hiring a professional to research your specific case for you.

Want some help with the planning? New Avenue homes offers an in-home design session with a trusted, experienced design professional. If you decide to proceed with your project, we'll handle the feasibility research for you.