Oceanside ADU Regulations & Zoning

Oceanside allows up to 2 detached ADUs for multifamily lots with an existing multi-family building. (Meaning: In order to build 2 ADUs, the property must already have at least a duplex on it, not just a single family dwelling)

Non‐livable space within existing multi‐family structures may be converted into an ADU. Examples of areas that can be converted include storage rooms and garage spaces. The maximum number of ADU allowed in a multi‐family structure is equal to 25% of the number of existing multi‐family units in the structure. Fractional units are rounded down. A minimum of one conversion ADU is allowed.

Whether or not ADUs are allowed does not depend on the zoning district, just the existing land use. If that site is currently a residential property, it can have an ADU. (Oceanside planning department, August 2023).

The height of a detached ADU can be up to 16′, or must comply with the setbacks of the zoning district in which it is located. (Meaning: You can build a taller ADU, but you will need to stick with regular setbacks, not the reduced 4′ setbacks).

Also, per recent state law change, detached ADUs within half a mile of major transit stops or high-quality transit corridors can be 18 feet tall. An additional 2 feet can be added if the ADU’s roof pitch matches the primary dwelling.

Read more about two story ADUs and height limits.

Yes, roof decks are permitted in accordance with underlying zoning (e.g. height limits of the zone).

The square footage of any attached ADU may not to exceed 50% of the primary dwelling square footage, or 1,200 sqft, whichever is less, but not less than 800 square feet.

If an accessory building is attached to the main building by at least a four-foot common wall, such accessory building shall be considered a part of the main building. (Clarified by City Planner in March 2023, “Per the Zoning Ordinance definition in Article 3, we use the definition of Accessory Building or Use: A building, part of a building or structure, or use which is subordinate and incidental to that of the main building, structure or use on the same lot.”)

The ADU shall be architecturally compatible with the primary dwelling in terms of design, building and roofing materials, colors, and exterior finishes. The ADU may have a flat or pitched roof.

While there is no specific code written regarding distance between structures outside the coastal zone, the city typically adheres to 6′ between structures (per a senior planner at the City of Oceanside in February 2022). The minimum required distance between structures is 10′ in the Coastal Zone.

Also, if the ADU is between 5 to 10 feet away from the primary residence, one of the structures need to be of fire-resistant construction. If beyond 10 feet from the primary residence, neither building is required to be of fire-resistant construction (per an assistant building official at the City of Oceanside in May 2022).

No, Oceanside allows digital submission of applications for an ADU.

Oceanside may require soils reports on a case by case basis, as determined by their Geotechnical consultant. The consultant has mentioned, “Along the coastal zone we would consider not requiring a soils report if the foundations are designed for 18” deep and slabs 5” thick. A good portion of the city has moderately to highly expansive soils, so many of the subdivisions have post-tensioned slabs or deepened reinforced footings and slabs. We are aware of these areas and will ask for a soils report to address the potentially adverse soils.”

Information above confirmed via email exchange with the City of Oceanside Engineering Division in December 2023.

Generally if ADUs are more than 300 feet outside of the coastline – even if in the coastal zone – the project will only need a building permit and do not need a coastal development permit (CDP). Those within 300 feet will need a CDP but no hearing is required.

As of July 2022, the City of Oceanside Planning Division has stated that based on past agreement with Coastal Commission staff, all ADUs built within the CCC Appeal Jurisdiction of the City’s Coastal Zone are subject to a Coastal Development Permit, except no hearing is required. Oceanside’s Appeal Jurisdiction Area is generally within 300 feet of the coastline.

The City reviews the proposed ADU for compliance with the Local Coastal Program and the Coastal Act during Building Permit Plan Check. Prior to issuing the building permit, the Planning Division sends a notice to surrounding property owners and the Coastal Commission, indicating that the City intends to approve an ADU. The permit can be appealed directly to the Coastal Commission within 20 days of the notice. ADUs outside of the Appeal Jurisdiction are not subject to a Coastal Development Permit (CDP) and only need a building permit.

The CDP is not a traditional coastal permit and the city does not require a separate fee. The applicant must provide a mailing list of surrounding property owners. The submittal process is simply applying for a building permit and the Planning Division will provide instructions during plan check.

Read more about ADUs in the coastal zone.

You may rent out an ADU for periods of more than 30 days. The City of Oceanside also prohibits you from renting out your primary residence as a short-term rental if you have an ADU on your property (see page 11 of the Oceanside ADU regulations – section E. 3.). However, in the case of ADUs on multi-family properties, there is no short-term rental restriction applied to existing multi-family units (so you could rent out a duplex, for instance, as an STR).

No, unless the ADUs meet the required setbacks for the SFR, in which case the height may be allowed to match the existing residence.

It is currently undetermined if two detached ADUs can be attached to each other; this will be subject to city interpretation.

Yes, existing non-livable space may be converted to ADUs (e.g. storage areas and garages). The minimum number of ADU conversions allowed is one, up to a maximum equal to 25% of the number of existing multifamily units. This is in addition to the allowed number of detached ADUs.

If a parking space is required, it may be located within the setbacks and in an existing driveway as tandem parking. Parking spaces don’t need to be replaced when a garage, carport, or covered parking structure is demolished in conjunction with the construction of an ADU or converted to an ADU.