ADU rules in Carlsbad, CA — also called accessory dwelling unit regulations or granny flat ordinances — cover setbacks, owner-occupancy, parking, and permit requirements.
Carlsbad permits accessory dwelling units (ADUs) and junior ADUs (JADUs) under CMC 21.10.030, originally adopted by Ordinance CS-384 and updated in 2025 to align with California Government Code sections 65852.2 and 65852.22. On a single-family lot you can build one detached or attached ADU plus one JADU (up to three units total). Detached ADUs are capped at 1,200 sq ft, attached ADUs at 50% of the primary dwelling (with an 800 sq ft minimum, 1,200 sq ft maximum), and JADUs at 500 sq ft. The ADU permit application is processed ministerially by Carlsbad Community Development without a public hearing or discretionary review when the design meets the objective standards in CMC 21.10.030.
Carlsbad's ADU zoning rules apply in any zone that allows one-family, two-family, multifamily, or mixed-use residential development (R-1, R-2, R-3, R-W, R-A, R-P, and the mixed-use components of V-B and the Village/Barrio Master Plan), provided an existing or proposed dwelling is on the lot. New detached ADUs must observe a 4-foot minimum side and rear setback when 16 feet or less in height; the front yard setback of the underlying zone still applies. A two-story detached ADU may reach up to 18 feet on a multifamily lot or up to 20 feet within a half-mile walking distance of a major transit stop, and an attached ADU may reach up to 25 feet or the underlying zoning height, whichever is less. No additional parking space is required when the ADU is (a) within a half-mile walk of public transit, (b) created entirely by converting existing space, (c) attached to the primary dwelling, or (d) in a historic district or located where on-street parking permits are required. Effective January 1, 2025, SB 1211 lets eligible multifamily lots add up to eight detached ADUs (not more than the existing unit count) and convert up to 25% of non-livable space to ADUs, with at least one conversion allowed; Carlsbad's 2025 amendment incorporated these limits and clarified that the 1,200 sq ft detached cap applies on single-family lots only. ADUs in the Coastal Zone also require a Coastal Development Permit under CMC Chapter 21.201, and for Local Coastal Program properties, CMC 21.10.030 setbacks (including the underlying front setback) take precedence over state ADU defaults. A recorded deed restriction prohibits rentals shorter than 30 days for any ADU permitted on or after January 1, 2020, and binds the JADU's owner-occupancy requirement. The ADU permit application package includes the building permit application, site plan, floor plans, elevations, an ADU checklist, the Hold Harmless Agreement, and (where applicable) the Coastal Zone forms. Plans are now submitted through the digital portal, and ministerial review under Government Code §65852.2(b)(1) requires a decision within 60 days of a complete application; coastal or other discretionary review can extend the window to 3–4 months.
Operating an ADU without a building permit is a code violation enforced by Carlsbad Code Enforcement, subject to stop-work orders, daily administrative fines, and required restoration. Using an ADU permitted on or after January 1, 2020 as a short-term rental violates the recorded deed restriction and the Short-Term Vacation Rental ordinance (CMC 5.60), and Carlsbad may revoke the ADU's certificate of occupancy. Coastal Zone ADUs built without the required Coastal Development Permit are subject to additional Coastal Commission enforcement.
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