In Redwood City, budget time for the fire flow test on a detached ADU. It's required at submittal and the city says lead time is several weeks, so order it early. If you own a rental, the new ordinance means a one-year lease offer at move-in and a city portal for no-fault notices. Treat that as a process, not a form.
Adding an ADU
In Redwood City
A fire flow test is required with the permit submittal for a new detached ADU. The city says typical lead time is several weeks.[1]
The city's estimated base fees for a new ADU are $3,999.53 for up to 400 square feet or a garage conversion, $4,660.62 for 401 to 600 square feet, and $5,321.71 for 601 to 800 square feet, plus other fees based on valuation.[1]
Redwood City runs a pre-reviewed ADU plan program that the city says reduces permit review to 30 days. You still need site-specific plans.[1]
State law, everywhere in California
A city has 60 days to approve or deny a complete ADU or junior ADU (JADU) permit application.[2]
Lot coverage, floor area ratio, and front setback rules can't be used to block an ADU of at least 800 square feet with four-foot side and rear setbacks.[2]
A city can't set a height limit below 16 feet for a detached ADU, or below 18 feet within a half mile of a major transit stop or high-quality transit corridor. Attached ADUs can go to 25 feet or the main home's zoning height, whichever is lower.[2]
A JADU is up to 500 square feet of interior space inside the main home. Owner occupancy can't be required for an ADU, but it is required for a JADU that shares a bathroom with the main home.[2]
No impact fees on an ADU of 750 square feet or less. Above that, fees have to be proportional to the main home.[2]
On a lot with an existing apartment building, state law allows up to eight detached ADUs (never more than the number of existing units), plus conversions of non-living space.[2]
Lot splits and second homes
In Redwood City
We did not find a Redwood City SB 9 page in official city sources. The state SB 9 rules above set the floor.[3]
State law (SB 9)
SB 9 applies to lots zoned single-family. It allows two primary homes on one lot, a split into two lots, or both, with staff-level approval and no public hearing.[3]
Local rules can't stop two homes of at least 800 square feet each, or a split into two lots of at least 1,200 square feet. Side and rear setbacks are capped at four feet.[3]
Parking is capped at one space per unit, and none can be required within a half mile walk of a high-quality transit corridor or major transit stop, or within a block of a car-share vehicle.[3]
To split a lot, you sign an affidavit that you intend to live in one of the units as your main home for at least three years. Any rental has to be for more than 30 days.[3]
SB 9 doesn't apply if the project would demolish or alter rent-restricted housing, rent-controlled housing, or housing a tenant has lived in during the last three years. It also excludes historic properties, lots with an Ellis Act withdrawal in the last 15 years, lots already created by an SB 9 split, and lots next to one the same owner split.[3]
The ceiling is four units total. After a split, the city has to allow two units on each new lot. The city must decide on a complete application within 60 days.[3]
Rent control and AB 1482
In Redwood City
Redwood City's Tenant Protection Ordinance took effect January 1, 2026. It adds minimum lease terms, just-cause eviction protections, and relocation assistance.[4]
Landlords must offer a one-year lease at initial lease-up. Just-cause protections apply once all tenants have lived in the unit 12 months, or one tenant has for 24 months.[4]
Rent increases follow the state cap: 5% plus the change in CPI, or 10%, whichever is lower. The ordinance itself exempts single-family homes and condos unless owned by a corporate entity, and properties built within the last 15 years.[4]
State law (AB 1482)
Under the Tenant Protection Act (AB 1482), rent can't go up more than 5% plus the change in the cost of living, or 10%, whichever is lower, in a 12-month period.[5]
After a tenant has lived in a unit for 12 months, the landlord needs a listed reason to end the tenancy, either at-fault (like nonpayment) or no-fault (like owner move-in or a substantial remodel).[5]
Exempt: units with a certificate of occupancy issued in the last 15 years (a rolling date), single-family homes not owned by a corporation or REIT, a duplex where the owner lives in the other unit, and units already under a stricter local rent control law.[5]
What is your Redwood City home worth, and what could it become?
I spent my career on the investment side, helping operate more than 7,000 units. I'll give you a valuation built from recent sales, and a straight read on what your lot allows: an ADU, a split, or neither.
Redwood City questions, answered
What does an ADU permit cost in Redwood City?+
The city's estimated base fees run from $3,999.53 (up to 400 square feet or a garage conversion) to $5,321.71 (601 to 800 square feet), plus fees based on construction valuation.[1]
Does Redwood City have rent control?+
No separate city cap. The city points landlords to the state limit of 5% plus CPI, or 10%, whichever is lower. Its Tenant Protection Ordinance, effective January 1, 2026, adds a one-year lease offer, just-cause rules, and relocation assistance.[4]
Do I need a fire flow test for an ADU in Redwood City?+
Yes, for a new detached ADU. It's part of the permit submittal and the city says lead time is several weeks.[1]
- [1]City of Redwood City, “Accessory Dwelling Unit Ordinance”
- [2]California Department of Housing and Community Development (HCD), “ADU Handbook (March 2026 update)”
- [3]California Department of Housing and Community Development (HCD), “Housing Law Fact Sheet: Duplexes and Lot Splits (SB 9), April 2026”
- [4]City of Redwood City, “Tenant Protection Ordinance”
- [5]California Attorney General, “Landlord-Tenant Issues: Tenant Protection Act”
Official Redwood City pages
This page is general information, not legal or tax advice. Rules change, and cities amend their codes after state reviews. Confirm current requirements with the city and a qualified professional before you buy, build, or change a tenancy. Erica Walters, REALTOR®, CalDRE# 02239622, Compass.