Oceanside | Legacy Homes

Maximum size 1200 square feet

Side/rear setbacks 4 feet or more if two stories)

Two story Yes

Building separation 6 feet (10 feet coastal)

Soils Report No

Building Verification Survey Yes

Coastal permit (in some areas) No permit required

Stormwater Mitigation No

Oceanside

On Oceanside single-family residential lots, you may build one ADU (either attached or detached) and one Junior ADU (JADUs have an owner occupancy requirement and must be converted from existing space within the primary residence).
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)

Effective Jan 2025 (SB1211): Multifamily property owners are permitted to build as many ADUs as there are existing units, with a maximum of eight detached ADUs. This change is due to California state law and will pre-empt existing local laws that are not brought into conformance.

Additionally, 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.

Per Oceanside ADU ordinance, you can build a detached ADU up to 1200 sqft. ADUs exceeding 850 sqft or 1,000 sqft with more than one bedroom, and/or a height of more than 16 feet must comply with height and maximum lot coverage for the underlying zone. ADUs under those thresholds are still granted reduced setbacks of 4′ on the side and rear. ADUs up to 800 square feet are exempt from lot coverage requirements. (Meaning: You can build an ADU of this size even if you’re maxed out on lot coverages).
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.
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.

ADUs must have 4′ minimum setbacks from rear and side yard property lines, with front yard setback per zoning standards. An ADU taking advantage of the 4′ setbacks cannot exceed 1000 sqft. ADUs exceeding 1000 sqft must comply with the setbacks of the underlying zone.
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).

Yes, Oceanside requires a building verification survey as part of the plan review process for an ADU. Note that in order to complete a building verification survey, a Boundary Survey must first be conducted to locate the property lines. Learn more about surveys.

Per the City of Oceanside Principal Planner via email in March 2023, “The building division requires a form board certification prior to pouring concrete which includes setbacks and elevations (if listed on plans) for all new ADUs. The only time this is waived if it’s a large parcel like in Morro Hills where the development is not close to the property lines.”
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.

A parking space is not required for an ADU in any of the following instances:

Within a one-half mile walking distance from public transit, which includes bus stops.

Within an established historic district.

Converted from the existing space of a primary residence or accessory structure, or are attached to an existing or proposed primary residence.

When on-street parking permits are required but not offered to the occupant of the ADU

When there is a car share vehicle located within a block of the ADU

Effective Jan 2025 (SB1211): When a garage, carport, covered parking structure, or uncovered parking space is demolished or converted for construction of an ADU, replacement parking will not be required.
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.

Oceanside ADU Regulations & Zoning