What San Rafael Allows.
San Rafael's ADU rules live in Municipal Code Section 14.16.285, and the city's official ADU page lays out the current standards. A detached ADU can have a maximum floor area of 1,000 square feet. An attached ADU is capped at 1,000 square feet or 50 percent of the existing residence, whichever is less, except that an ADU of up to 800 square feet must always be allowed. A Junior ADU must be between 150 and 500 square feet and contained entirely within the single-family home, and an ADU created by converting existing interior space of the primary residence has no maximum size limit.
On a single-family lot you are not limited to one unit type. San Rafael allows one detached ADU, one attached ADU, or one JADU, and also permits a combination of one detached or attached ADU, one JADU, and one conversion ADU on the same property. Multifamily properties get their own allowance: at least one conversion ADU, up to 25 percent of the existing unit count, from spaces like storage rooms or garages, plus up to two detached ADUs on the same lot. If you own apartments or manage a portfolio in San Rafael, see how Abodu approaches multifamily ADU projects.
Setbacks, Heights, And Lot Standards.
New attached or detached ADUs need just 4-foot rear and side yard setbacks, and conversions that keep the existing footprint need no additional setbacks at all. San Rafael's rules also include a powerful override: regardless of lot coverage, floor area ratio, natural state, or other standards, you are allowed an ADU of up to 800 square feet as long as it meets the 4-foot setbacks and height limits. That single provision rescues many smaller and oddly shaped Marin lots.
Height limits depend on where the unit sits. A detached ADU can reach 16 feet on a standard lot, or 18 feet if the property is within a half-mile walking distance of a major transit stop or on a lot with a multi-story multifamily building. Attached ADUs can go up to 25 feet or the underlying zoning height limit, whichever is lower, with a special 17-foot cap in the Eichler-Alliance overlay district. One parking space per ADU is the default, but it is waived near transit, for conversions, and in several other cases, and JADUs never require parking. Fire sprinklers cannot be required in the ADU if they are not required for the main house. Not sure how these standards land on your property? Check your lot and Abodu will map it for you.
Hillside And Fire Zone Realities.
San Rafael takes wildfire seriously, and it shows up in the building rules. The city has extended wildfire construction standards citywide: requirements that once applied only to parcels in the Wildland Urban Interface (WUI) now apply to all parcels in San Rafael, including fire-resistant building materials meeting California Fire Code Chapter 7A. The city explains the change on its wildfire building codes page, reasoning that embers travel well beyond mapped fire zones.
Hillside and WUI parcels also face extra process. San Rafael's pre-approved ADU plan program is limited to parcels outside hillside, WUI, USGS geology, and tsunami inundation zones, which tells you exactly which sites the city considers straightforward and which need closer review. If your property sits in unincorporated Marin rather than inside city limits, different county rules apply; start with our Marin County ADU guide instead.
Permits, Timelines, And Fee Waivers.
ADU permits in California are ministerial, meaning no public hearing and no discretionary review. Under Government Code Section 66317, San Rafael must approve or deny a complete ADU application within 60 days, and if it does not act in time, the application is deemed approved. The state's rules are summarized in the California HCD ADU handbook.
San Rafael sweetens the deal on smaller units: for ADUs under 750 square feet, the city waives impact fees, general plan maintenance fees, street maintenance fees, and bedroom taxes. The city has also launched a pre-approved plan program to expedite detached ADU permits, though as of this writing it lists no approved plans yet. Abodu's engineered, factory-built homes arrive with complete permit-ready documentation, and our team manages the submittal and city correspondence end to end. See exactly how the process works.
What It Actually Costs.
Budget honesty matters more than any zoning table. Custom site-built ADUs in California routinely exceed $250,000 before change orders, and hillside foundations, fire-rated assemblies, and long construction timelines can push San Rafael projects well past that. Abodu takes a different approach: transparent published pricing: homes from $234,800 plus a published installation price, an expected all-in from $298,800 that covers design, permits, factory build, delivery, and installation, with no surprise change orders along the way.
Because the home is built in a factory while your site work and permits move in parallel, your backyard stays livable and the schedule stays predictable. Read about how the process works, hear from homeowners who have done it, or check your lot to see what fits in your San Rafael backyard.