Del Mar ADU Regulations & Zoning

Del Mar 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.

The height of a detached ADU can be up to 16′, though an ADU proposed within the Bluff, Slope, and Canyon Overlay Zone shall be 14′ height maximum.

On a lot that is within one-half mile walking distance of a major transit stop or a high-quality transit corridor, as defined in Section 21155 of the Public Resources Code, the
maximum building height of a detached ADU, shall not exceed 18 feet above grade. An additional 2 feet can be added if the ADU’s roof pitch matches the primary dwelling.

The maximum building height for an attached ADU shall not exceed 25 feet above grade, two stories, or the base zoning requirements; whichever is lower. This shall only apply where an ADU is attached to a primary dwelling unit.

So yes, you could build a two story ADU in some situations. Read more about two story ADUs and height limits.

No, roof decks are not permitted on detached ADUs in Del Mar.

The square footage of the ADU shall not exceed 850 square feet in size, or 1,000 square feet maximum if the ADU has more than one bedroom. A proposed, attached ADU shall also be subject to an additional limit of a maximum size of 50 percent of the habitable space of the primary dwelling unit.

The ADU shall comply with the following objective design standards, unless
the design standards prohibit construction of an 800 sq. ft. ADU, notwithstanding Section 30.91.040(G)(5):

1. Wall and roof planes on each elevation must be varied with at least one projection, offset, or recess of the building (of at least one foot in depth) for each 20 feet.
2. Walls and windows shall be located so that sight lines maximize privacy and avoid direct views into neighboring homes. Glass walls (any wall plane consisting of more than 75 percent opaque or transparent glazed surface) that are visible from adjacent neighboring homes shall be prohibited. Sizing and placement of windows shall be offset to stagger the window placement in relation to the adjacent neighbor’s windows; or shall utilize obscured or opaque window glass, clerestory windows, or windows with higher sills. Installation of skylights shall be tinted to avoid interior light transmission.
3. Rooftop decks are prohibited.
4. Where provided, fireplaces and chimneys shall be attached to the ADU and shall be no higher than the minimum height required per the California Building Code.
5. ADU roof eaves shall not encroach into four (4) foot side or rear setback.
6. New detached or attached accessory dwelling units shall be constructed using the same architectural style, roof pitch, exterior building materials, colors and finishes as the primary unit if the accessory dwelling unit is attached to or located within twenty (20) feet of the primary dwelling unit.

A minimum of six feet between buildings shall be maintained between a detached accessory dwelling unit and all other buildings and structures on the lot.

Yes, Del Mar requires a certification of height, setback, and square footage compliance shall be submitted prior to framing inspection.

California Gov. Code § 65852.2 provides that the ADU statutes do not supersede or in any way alter or lessen the effect or application of the California Coastal Act, except that the City shall not be required to hold public hearings for Coastal Development Permit applications for ADUs.

The following are exempt from a Coastal Development Permit, except where a permit is otherwise required pursuant to Section 30.91.030(C)(5)(c):

i. The ADU contained entirely within or attached to an existing single dwelling unit.
ii. Minor changes to an existing residential structure that will not involve the removal or replacement of major structural components (e.g. roofs, exterior walls, or foundations) and will have no potential to adversely impact coastal resources pursuant to the certified LCP.

Read more about ADUs in the coastal zone.

No, Del Mar does not mandate soils reports for ADUs, except in the Coastal Bluff Overlay Zone.

Yes, Del Mar requires site drainage and storm water mitigation for ADUs. Finish grading work to create a bio-swale, drainage basin or other contouring work to handle on-site storm water will cost around $5-10K in most cases. Read more about stormwater mitigation for ADUs.

No, you cannot stack ADUs on top of each other in Del Mar.

Yes, you can attach two ADUs to each other in Del Mar.

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.