ADU plus JrADU
Del Mar's code hides a fork in the road (Del Mar Municipal Code Chapter 30.91 (June 2025)). On a single dwelling lot, you can have one ADU and one JrADU, but only if the ADU is detached. Build the ADU inside the house, attach it, or attach it to the garage, and the JrADU is gone.
| Path | What you can build | JrADU too? |
|---|---|---|
| ADU within the house or a garage (attached or detached) | One ADU inside existing walls; up to 150 sq ft added only for ingress or egress | No |
| Attached ADU (addition sharing a common wall) | One ADU added to the house | No |
| ADU attached to an existing garage | One ADU joined to the garage (no other accessory structure) | No |
| Detached ADU (new or converted accessory structure) | One detached ADU | Yes, one JrADU inside the house or attached garage |
Source: DMMC §30.91.040(B).
What each path gives you
| Path | Homes added | Size |
|---|---|---|
| Detached ADU + JrADU | Two | 850/1,000 sq ft + 500 sq ft |
| Attached ADU | One | 50% of the house |
| ADU within house or garage | One | Existing space + 150 sq ft for entry |
Who the two-unit path suits
Families with a parent who wants independence close by and an adult child who needs a suite. Or an owner who wants one long-term rental and one family space. Note the JrADU requires the owner to live on the property.
What to check first
- Your zone allows JrADUs (R1 zones and listed CVPP lots)
- There's room for a detached ADU with 6 ft building separation
- Protected trees and slopes allow a pad
- A JrADU entry can be added to the house
A note on bonus JrADUs
Under the Incentive Program, an owner who deed-restricts an ADU for a low-income household can get a bonus JrADU and a 500 sq ft FAR bonus. See affordable ADUs.
Order of work
You can build in either order. Some owners convert space to a JrADU first, then add the detached ADU later. Just don't build an attached or interior ADU first, since that rules out the JrADU.
Cost and review differences
A JrADU inside the house skips Del Mar's engineering review, which applies to new attached and detached ADUs. A JrADU of 500 sq ft or less is also exempt from impact fees under state law. So the JrADU is often the quick, low-cost half; the detached ADU carries the engineering package.
Checklist for both
- One verification form per unit
- JrADU entry and efficiency kitchen
- Detached ADU site plan at 1 in = 10 ft
- Sewer lateral video
Also checked Oct 14, 2026: Del Mar ADU Application Packet (Rev. 2024) · HCD ADU Handbook (March 2026).
Sources, checked Oct 14, 2026: Del Mar Municipal Code Chapter 30.91 (June 2025).