The Complete Alameda ADU Requirements Guide
If you’re planning to build an accessory dwelling unit (ADU) in Alameda, it’s important to understand the city’s current permitting rules requirements. An ADU is a self-contained housing unit that shares a lot with a larger main residence. Done right, it can add rental income, multigenerational living space, or simply a more flexible footprint to the property you already own.
Alameda follows California’s state-mandated ADU policies, but adds its own design and site-specific requirements. Whether you’re planning a detached structure or a conversion, the process is relatively streamlined. Below, you’ll find the key requirements—size, height, setbacks, parking, and more—plus how Samara can help you get it done.
Alameda ADU regulations at a glance
Alameda’s ADU ordinance aligns with California state law and applies uniformly across all neighborhoods in the city. If a local rule conflicts with state law, the more flexible state standard applies.
Most ADU permit applications in Alameda will be reviewed within 60 days, and are typically approved within three to four months.
Size and lot requirements
The minimum ADU size in Alameda is 150 square feet. The maximum size depends on the ADU type:
- Detached ADUs can be up to 1,200 square feet. At least 800 square feet is always allowed, regardless of zoning rules. Height is limited to 16–18 feet depending on location, with extra height allowed to match the main home’s roof or meet flood requirements.
- Attached ADUs can also be up to 1,200 square feet. They can be built up to 25 feet tall or match the main home’s height limit, whichever is lower.
- Junior ADUs (JADUs) are limited to 500 square feet and must be contained entirely within the walls of the main home.
All new ADUs must have at least 4-foot side and rear setbacks. Detached units also need to be 6 feet from other buildings. Setback rules don’t apply when converting an existing structure. Extra height is allowed in flood zones to meet elevation standards.
Meet the KurodasDesign requirements
Alameda applies objective design standards to ADUs:
- Detached ADUs that are visible from the street must use similar materials, windows, and rooflines as the main house. Some flexibility applies to prefab and modular units.
- Attached ADUs must match the architectural style of the main home and use the same materials and colors. No changes are allowed to the street-facing façade, and the ADU’s entrance cannot face the street.
There’s no limit on the number of bedrooms as long as the design meets building code. Protected trees can’t be removed without approval from a certified arborist.
Parking requirements
Off-street parking isn’t required for ADUs or JADUs in Alameda. You also don’t have to replace parking if a garage, carport, or driveway is removed or converted.
Zoning eligibility
ADUs are allowed on any residential or mixed-use lot, as long as there’s an existing or proposed home on the property.
Number of ADUs allowed
On a single-family lot, you can build one full-size ADU (attached or detached), plus one JADU inside the main home.
On a multifamily lot, you can build up to 8 detached ADUs, so long as the number does not exceed the count of primary units, plus multiple conversion ADUs within the existing building, up to 25% of the unit count.
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Streamline your ADU in Alameda
If you’re looking to build an ADU, Samara makes it easy. We handle everything from permits to installation and even offer our own financing. Call us at 650-420-2607 to schedule a 15-minute consultation and discover how simple adding a Backyard ADU can be.
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