What You Can Build in Redwood City.
Redwood City's ADU rules live in Article 37 of the Zoning Code, and they are friendlier than most homeowners expect. A single-family lot may add one ADU plus one junior ADU (JADU), and neither counts toward the lot's allowed density. A standard ADU can reach 850 square feet, a unit with more than one bedroom can reach 1,000 square feet, and a unit built to California Building Code accessibility standards can go up to 1,200 square feet. A JADU is capped at 500 square feet, sits entirely within the single-family home, and may share a bathroom with it.
The city also recognizes the state's protected unit: a new detached ADU of up to 800 square feet and 16 feet tall with 4-foot side and rear setbacks must be approved with only a building permit. Better still, ADUs are exempt from lot coverage calculations, no parking spaces are required, and if you demolish a garage or carport to make room, no replacement parking is required either. Curious what fits on your specific parcel? Check your lot and Abodu's local team will map it for you.
Setbacks, Height, and Placement.
New detached ADUs need just a 4-foot setback from side and rear property lines, while the front yard follows the setback that applies to the main house. Converting an existing garage or accessory building? No setback at all is required, as long as side and rear clearances are sufficient for fire safety, and you can even rebuild in the same footprint at the same dimensions.
Height limits are generous by Bay Area standards: a detached ADU may rise to 20 feet with a flat roof or 24 feet with a pitched roof, with the extra 4 feet devoted solely to roof pitch. Two-story designs are allowed, though no more than 600 square feet may sit above the first floor, and balconies, decks, and open stairways must face the interior of the site rather than adjacent side or rear yards. Abodu's single-story homes clear these limits with room to spare.
Multifamily Lots Get ADUs Too.
Article 37 is not just for single-family homes. A lot with a duplex or multifamily building may add up to two detached ADUs, each up to 16 feet tall with 4-foot rear and side setbacks. On top of that, owners may convert non-livable space, such as storage rooms, boiler rooms, attics, basements, or garages, into at least one ADU and up to 25 percent of the existing unit count, provided each unit meets state building standards.
For property owners and operators, that is a fast, by-right path to new rental income on land you already own. Abodu builds for these projects at scale; see how it works on our multifamily page.
Permits, Timelines, and Hometown Programs.
Review is ministerial: the city must act on a complete ADU application within 60 days, with no public hearing and no discretionary design review, consistent with California HCD's statewide ADU framework. Applications go in online through the city's eTrakIt portal, and new detached ADUs need a fire flow test to confirm water supply, so plan for its roughly four-week lead time.
Redwood City is also rolling out a pre-reviewed ADU plan program under AB 1332 that cuts the city's review window to 30 days for qualifying designs, and it partners with HEART of San Mateo County to offer free pre-reviewed plans through the GLADUR program. The San Mateo County ADU Resource Center, a joint effort that includes Redwood City, walks homeowners through every step. One more local perk: no impact fees on ADUs under 750 square feet, and the city publishes base building fee estimates of roughly $3,824 to $5,088 depending on unit size. Full details are on the city's ADU Ordinance page.
What It Actually Costs.
Permit fees are the small line item. The real number to watch is construction: custom site-built ADUs in California routinely exceed $250,000 before change orders, and the final bill is a moving target until the last invoice lands.
Abodu works differently, and nowhere more so than in our own hometown. You get 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, handled by a team headquartered right here in Redwood City. See how the process works, or hear from neighbors on our testimonials page.