San Clemente ADU rules

Maximum size

An attached or detached ADU may have up to 850 sq ft of interior livable space for a studio or one bedroom, or 1,000 sq ft for two or more bedrooms. These limits do not apply to an ADU converted from existing space of a home or accessory structure. Other standards may reduce the size, but setbacks, floor area, open space or site coverage cannot reduce an ADU below 800 sq ft when there is no other way to comply. Basement or other non-living area used for an ADU does not count toward the floor area limit.

Source: San Clemente Municipal Code § 17.28.270 Accessory Dwelling Units, as amended by Ordinance 1810 (Municode), § 17.28.270(E)(4)-(5), accessed 2026-11-03.

Setbacks

New attached and detached ADUs need at least 4 ft from side lot lines and from rear lot lines that do not abut an alley (less if the zone allows less). The zone's front setback applies unless it would physically prevent a qualifying ADU. No added setback is needed for a conversion of existing space, garage or carport, or for a same-size rebuild in the same footprint. On a lot that abuts a property on the California Register of Historical Resources, the ADU must sit outside the front yard setback unless there is no other room for an 800 sq ft ADU.

Source: San Clemente Municipal Code § 17.28.270 Accessory Dwelling Units, as amended by Ordinance 1810 (Municode), § 17.28.270(E)(2), (H), accessed 2026-11-03.

Coastal Zone

Parts of San Clemente near the shore are in the Coastal Zone. There, an ADU also needs a coastal development permit from the California Coastal Commission before the City issues permits: you first apply to the City for an in-concept review, then to the Coastal Commission. In the Coastal Zone, parking can also be required for an ADU built with a new home, and garage or carport spaces removed for an ADU may have to be replaced. This lookup cannot tell whether a parcel is in the Coastal Zone; check with the Planning Division.

Source: City of San Clemente, ADU Development Standards handout, Review Process, step 1, accessed 2026-11-03.

Local ADU rules

San Clemente's ADU rules are in Municipal Code section 17.28.270, rewritten by Ordinance 1810 (adopted June 16, 2026, in effect 30 days later) to follow state ADU law. ADUs and JADUs need a building permit and are reviewed under state law (Gov. Code §§ 66317 and 66335), without a hearing. ADUs of the types listed in Gov. Code § 66323 are not held to local standards that conflict with that section.

Source: San Clemente Municipal Code § 17.28.270 Accessory Dwelling Units, as amended by Ordinance 1810 (Municode), § 17.28.270(C), (J), (K), accessed 2026-11-03.

Number and types of ADUs

On a lot with a single-family home: one attached or converted ADU (an accessory structure may grow up to 150 sq ft for entry and exit), one new detached ADU, one converted detached accessory structure, and one JADU. These may be combined. On a lot with an existing multifamily building: converted ADUs in non-livable space (at least one, up to 25% of the existing units) and up to 8 detached ADUs, not more than the number of existing units. On a lot with a proposed multifamily building: up to 2 detached ADUs. JADUs are not allowed on multifamily lots.

Source: San Clemente Municipal Code § 17.28.270 Accessory Dwelling Units, as amended by Ordinance 1810 (Municode), § 17.28.270(D), accessed 2026-11-03.

Height

A detached ADU may be 16 ft. It may be 18 ft on a lot with a multistory multifamily building, or within a half mile walk of a major transit stop or high-quality transit corridor, where 2 more ft are allowed to match the main home's roof pitch. An ADU over a detached garage may be two stories, up to the zone's height limit, if it meets the zone's setbacks and the main home meets parking standards. An attached ADU, or one inside the home, follows the zone's height limit.

Source: San Clemente Municipal Code § 17.28.270 Accessory Dwelling Units, as amended by Ordinance 1810 (Municode), § 17.28.270(E)(3), accessed 2026-11-03.

Parking

One parking space per ADU, which may be tandem or on an existing driveway. No space is needed for a JADU; for an ADU inside a new home or converted from existing space of a home or accessory structure; within a half mile walk of public transit (including SC Rides pickup spots); in a historic district or the City's Architecture overlay; where on-street permits are required but not offered; or within one block of a car share vehicle. Outside the Coastal Zone, no space is needed for an ADU filed with a new home, and garage or carport spaces removed for an ADU do not have to be replaced.

Source: San Clemente Municipal Code § 17.28.270 Accessory Dwelling Units, as amended by Ordinance 1810 (Municode), § 17.28.270(E)(9), accessed 2026-11-03.

Junior ADUs

One JADU of up to 500 sq ft of interior livable space is allowed inside a proposed or existing single-family home (an attached garage counts), with an efficiency kitchen and its own exterior entrance. It may be added along with an ADU. The owner must live on the property only if the JADU shares a bathroom with the home. A deed restriction must be recorded before the building permit is issued.

Source: San Clemente Municipal Code § 17.28.270 Accessory Dwelling Units, as amended by Ordinance 1810 (Municode), § 17.28.270(D)(6), (E)(4)(d), (G)(3)-(4), accessed 2026-11-03.

Fees, utilities and renting

No impact or connection fee for an ADU with less than 750 sq ft of interior livable space; larger ADUs pay in proportion to the main home's size. An ADU built with a new home needs its own utility connection; an ADU created inside a home does not. Fire sprinklers are needed only if the main home needs them. ADUs and JADUs may not be rented for 30 days or less, and may not be sold separately except as state law allows (Gov. Code § 66341).

Source: San Clemente Municipal Code § 17.28.270 Accessory Dwelling Units, as amended by Ordinance 1810 (Municode), § 17.28.270(E)(6), (F), (G)(1)-(2), accessed 2026-11-03.

State housing department (HCD) review

On October 14, 2025, HCD found that San Clemente's earlier ADU ordinance (Ordinance 1742, December 2022) did not comply with state ADU law on several points, including limits on combining ADU types, the cap of two detached ADUs on multifamily lots, height near transit, owner occupancy, deed restrictions on ADUs, car share parking wording, design matching rules and legalizing older unpermitted units. The City had until November 13, 2025 to respond. It then adopted Ordinance 1810 in June 2026, which replaced the section. Confirm the current rules with the City of San Clemente.

Source: HCD ordinance review letter, City of San Clemente, Letter of October 14, 2025, accessed 2026-11-03.