On single-family residential lots in Mountain View, you can build one detached ADU with a minimum 4-foot side and rear setback. A JADU may be combined with this ADU. There is no minimum lot size requirement.

Multifamily properties in Mountain View can build multiple ADUs within existing non-livable spaces (storage rooms, boiler rooms, attics, basements, garages). At least one ADU is allowed, and up to 25% of existing units may be converted into ADUs. No more than two detached ADUs are allowed on multifamily lots.

Yes, Mountain View allows Junior ADUs up to 500 square feet. A JADU must be located entirely within the existing single-family home, including attached garages. JADUs require owner-occupancy—you must live in either the primary dwelling or the JADU. A current grant deed is required for JADU permits to prepare the covenant.

Mountain View does not have a separate guest quarters classification. Any secondary living space with kitchen facilities would be classified as an ADU.

Mountain View does not have a separate guest quarters classification. Any secondary living space with kitchen facilities would be classified as an ADU.

Attached ADUs are limited to 50% of the primary residence's floor area, with no explicit maximum cap beyond the 1,200 square foot state maximum. Attached ADUs must connect to the primary dwelling and follow its setback requirements.

Yes. Under California state law, ADUs up to 800 square feet are exempt from lot coverage, FAR, and open space requirements. This means you can build an 800 square foot ADU even if your lot is otherwise at maximum coverage.

Detached ADUs have a maximum height of 16 feet. Attached ADUs can match the height of the primary dwelling up to 25 feet. Conversion ADUs have no height limit since they use existing structures.

Mountain View generally limits detached ADUs to single-story construction. Two-story additions may be possible as attached ADUs following the primary dwelling's height regulations, but detached two-story ADUs face significant restrictions.

Detached ADUs require minimum 4-foot side and rear setbacks, plus 6 feet from any existing structures. No setback is required for an ADU that replaces an existing structure in the same location and dimensions. Front setbacks follow the underlying zoning requirements.

Mountain View requires detached ADUs to be at least 6 feet from the primary residence and any other existing structures on the lot.

Mountain View processes ADU permits ministerially when they meet all requirements. Building review typically takes about 20 business days for complete applications. Overall, expect 2-4 months from submission to permit issuance. Contact the Planning Division at 650-903-6306 for preliminary design review.

Building permit fees range from $3,000 to $6,000 based on construction valuation. Conversion ADUs typically cost $3,000-$5,000 in permit fees. If excavation is needed for utility improvements, an excavation permit fee of up to $12,000 may apply. ADUs under 750 square feet qualify for reduced impact fees.

A site survey prepared by a licensed civil engineer or land surveyor is required for structures within 6 feet of a property line or required setback. You must obtain approval from the City prior to the concrete pour for the foundation. Soils reports are not routinely required.

No additional parking is required for JADUs, studio ADUs on single-family lots, or ADUs on multifamily lots. For 1+ bedroom ADUs on single-family lots, one space is required unless the property is within 0.5 miles walking distance of public transit (including bus stops). Most Mountain View properties qualify for the transit exemption.

No. When converting a garage or carport to an ADU, replacement parking is not required under California state law.

If parking is required, it can be located in a garage, carport, or as tandem parking in a driveway. Parking can also be placed within setback areas or the front yard per city standards.