Multifamily and Duplex Properties for Sale in Del Mar: Zoning and Rent Rules

What multifamily in Del Mar looks like

Multifamily in Del Mar mostly means duplexes, two detached units on one lot, and a limited number of older small apartment and condominium buildings near the village. The city’s residential zones were written around single-family and duplex lots, so apartment buildings are rare and new ones arrive mainly through commercial-zone housing and the Housing Element overlay. Small-property buyers should start with our guide to financing 2-4 unit properties; for a larger building see apartment building loans.

Where the zoning allows it

Junior ADUs are not permitted in RM-West or R2, though a standard ADU is. In NC, the 20-unit density does not apply on parcels next to the San Dieguito River and Lagoon. Del Mar also has a Chapter 30.93 for two-unit development on single-family lots, the local version of SB 9; see our SB 9 lot split guide and ADU investment guide, and confirm coastal permit needs.

Inclusionary housing. Chapter 24.21 applies to projects of two or more units and to condominium conversions of two or more units. Projects under 30 net-new units must set aside 15%, rounded up; 30 or more units, 20%. A two-unit condo conversion needs one low-income unit or an in-lieu fee, and affordability lasts at least 55 years.

Unit loss fee. In RM-West, a project that reduces the number of units on a lot owes a Housing Reduction Mitigation Fee per unit lost, except units removed only to bring an over-dense lot into conformance. Converting an old duplex back to a single house has a cost.

Rent rules: state law only

We found no Del Mar rent control or local just cause ordinance on official sources, and the Attorney General’s rent cap page lists no San Diego County city locally. Covered units follow the Tenant Protection Act, with the San Diego Area cap listed at 8.8% for increases starting August 1, 2025 and 8.2% for increases from August 1, 2026 through July 31, 2027. Many Del Mar duplexes are owner-occupied, which can affect exemptions; see our AB 1482 guide and just cause eviction guide.

Del Mar rental property rules

Short-term rentals. This is the rule that most changes Del Mar underwriting. The city’s STR background page says the Council adopted new regulations on September 23, 2024, pending Coastal Commission certification, and that until they take effect STRs are not allowed in any residential zone, only in commercial zones and specific plan areas. Under the adopted Chapter 30.96, RM and R2 zones would open to STRs, but new permits must be in the owner’s primary residence, apartment developments and ADUs in residential zones are excluded, stays must be at least three nights, and the citywide cap is 129 permits. Permits are not transferable and end on sale, so a buyer cannot inherit a seller’s STR income.

Coastal permits. Under Chapter 30.75, converting multi-unit rental housing to condominium or timeshare ownership is not exempt from a coastal permit, and improvements that change the intensity of use need one. The Director can issue coastal permits for by-right Chapter 30.92 units and two-unit developments under Chapter 30.93.

Coastal hazards, utilities and older buildings

Much of Del Mar’s multifamily-zoned land sits near the beach, the bluffs or the lagoon, where the beach, bluff, lagoon and floodplain overlays in Title 30 add review. Water and wastewater are city services billed together per the city’s utility FAQ. Older duplexes and small buildings should get a sewer lateral camera inspection and a review of wood framing, and buildings with three or more units and elevated balconies need SB 721 inspections.

Underwriting a Del Mar multifamily purchase

1. Confirm the zone and overlays, and match the legal unit count to permits and density.
2. Assume long-term leases only unless an STR permit is confirmed in your name after closing.
3. Classify units under AB 1482 and model increases at or below 8.2%.
4. Check whether any plan to reduce or convert units triggers the mitigation fee, inclusionary rules or a coastal permit.
5. Collect leases and statements, and obtain estoppel certificates.
6. Inspect laterals, framing and balconies, and rebuild taxes on the new assessed value in our rental property analysis.

Questions people ask

Sources & notes

1. DMMC 30.17, RM-West
2. DMMC 30.20, R2
3. DMMC 30.21, RC
4. DMMC 30.22, CC, 30.24, NC and 30.25, PC
5. DMMC 30.92, Housing Element overlay
6. DMMC 24.21, inclusionary housing
7. DMMC 30.75, coastal development permits
8. DMMC 30.96, short-term rentals
9. City of Del Mar, STR background
10. City of Del Mar, water and sewer FAQ
11. Del Mar Title 30 index
12. California Attorney General, rent caps (updated July 16, 2026)

STR rules were in transition when reviewed; confirm current status with the city. General information, not legal or tax advice. Last reviewed October 2026 by Matthew Martinez.

Related: Del Mar real estate guide · Commercial real estate in Del Mar · Multifamily investing guide · Investor services