On single-family residential lots in Sunnyvale, you can build one ADU (attached or detached) and one Junior ADU (JADU). There is no minimum lot size requirement for ADU eligibility. Your property must be zoned for residential use (R-0, R-1, R-1.5, R-1.7/PD, R-2, or similar).

Multifamily properties in Sunnyvale can build up to two detached ADUs with 4-foot setbacks. Additionally, you can convert non-livable spaces (such as storage areas, garages, or basements) into ADUs—up to 25% of the existing unit count.

Yes, Sunnyvale allows Junior ADUs up to 500 square feet. A JADU must be located entirely within the existing footprint of the primary residence. JADUs may share a bathroom with the main home but must have a separate entrance and an efficiency kitchen. JADUs have an owner-occupancy requirement—either the JADU or the primary dwelling must be owner-occupied.

Sunnyvale does not have a separate guest quarters classification. Any secondary living space with kitchen facilities would be classified as an ADU and count toward your allowable units.

Detached ADUs in Sunnyvale can be up to 800 square feet for streamlined (ministerial) approval. Larger ADUs up to 850 square feet for one-bedroom units, or 1,000 square feet for two or more bedrooms, may be allowed through non-streamlined review. ADUs up to 800 square feet are exempt from lot coverage and FAR requirements.

Attached ADUs are limited to 850 square feet for a one-bedroom unit, or 1,000 square feet for two or more bedrooms. Attached ADUs cannot exceed 50% of the existing primary dwelling's floor area. The ADU must share a wall or roof structure with the main residence.

Yes. Under California state law and Sunnyvale's ordinance, ADUs up to 800 square feet are exempt from lot coverage and FAR (floor area ratio) requirements. This means you can build an 800 square foot ADU even if your lot is otherwise at maximum coverage. ADUs do not count toward the 45% FAR or 3,600 square foot threshold for Planning Commission review.

Detached ADUs have a maximum height of 16 feet (measured from the average finished grade within five feet of the structure). Attached ADUs follow the same height limitations as the primary dwelling unit. If you already have a JADU on the property, state law limits additional ADU height to 16 feet.

Two-story ADUs are only allowed above the primary dwelling unit—not as standalone detached structures. Second-story windows must comply with privacy requirements if within 20 feet of a rear property line or 7 feet of a side property line. These windows must have opaque or translucent glazing if the sill height is within 5 feet of the finished floor.

Detached ADUs require a minimum 4-foot setback from the side and rear lot lines. Setbacks of less than 4 feet are allowed if the ADU replaces an existing structure in the same location and dimensions. Attached ADUs must comply with the same setback requirements as the primary dwelling. Front yard setbacks follow the underlying zoning requirements—detached ADUs are not allowed in the front yard.

Sunnyvale requires detached ADUs to be at least 10 feet from the primary residence. This separation requirement ensures adequate fire safety and privacy between structures.

Sunnyvale offers two permit paths: streamlined (ministerial) approval for ADUs meeting specific criteria, and non-streamlined review for larger or more complex projects. Streamlined ADUs typically receive approval within 60 days. Overall, expect 2-4 months from application to permit issuance. Contact the One-Stop Permit Center at (408) 730-7444 for guidance.

Permit costs in Sunnyvale vary based on project scope and valuation. Building permit fees are based on construction valuation, typically ranging from $5,000 to $15,000 for standard ADU projects. Land development fees may apply for utility connections. ADUs under 750 square feet qualify for reduced or waived impact fees.

Sunnyvale does not routinely require soils reports for standard ADU projects. A site survey prepared by a licensed civil engineer or land surveyor is required for structures within 6 feet of a property line. Building surveys are also not typically required unless there are questions about property line locations.

No new parking is required for ADUs in Sunnyvale. This applies to both attached and detached ADUs. If parking is voluntarily provided, it must meet city development standards. This waiver makes ADU construction more feasible on smaller lots.

No. When an existing garage is converted to an ADU, replacement parking is not required. This aligns with California state law, which prohibits cities from requiring replacement parking for garage conversions.

Since parking is not required for ADUs in Sunnyvale, this is generally not a concern. If you choose to provide parking voluntarily, it can be located in a driveway or elsewhere on the property per city standards.