Del Mar ADU cost and fees
We don't quote construction prices. Here are the city fees and the drivers.
| Fee (FY 2027, effective July 1, 2026) | Amount |
|---|---|
| Planning: Accessory Dwelling Unit | $1,227 |
| Engineering: ADU review and inspection (one review cycle) | $771 |
| Engineering: additional ADU review | $534 |
Source: Del Mar FY 2027 fee schedule.
Building permit fees, impact fees for ADUs of 750 sq ft or more under state law, school and utility fees are separate. Under Chapter 30.91, ADUs aren't new residential uses for utility connection fees; connection fees apply only outside existing structures, proportionate to size and fixtures.
Cost drivers in Del Mar
- Matching materials and plane offsets
- Protected tree protection
- Geotechnical reports near bluffs
- Flood elevation in FEMA zones
- Grading up to 200 CY
- Dark Sky lighting and equipment screening
- Construction parking plan on tight streets
What's collected when
| Item | When | Notes |
|---|---|---|
| Planning ADU fee | With the application | FY2027 schedule: $1,227 |
| Engineering ADU review | At submittal, only for new attached or detached ADUs | FY2027 schedule: $771; additional review $534 |
| Encroachment permit | Before any work in the public right-of-way | Separate permit |
| Building permit fees | At building permit | Per Chapter 23.04 review |
| Impact fees | Per state law | None at 750 sq ft or less; proportional above |
| School fees | At building permit, if levied | None under 500 sq ft of interior livable space |
Sources: Del Mar FY2027 fee schedule, ADU Application Packet, HCD ADU Handbook (March 2026).
Which projects skip engineering review
Del Mar's engineering checklist says review isn't required for an ADU created inside the existing house or an existing accessory structure, or for a garage converted to an ADU. That skips the Engineering ADU fee and much of the site-plan package, which is one reason conversions and JrADUs are the lower-cost route here.
| Project | Engineering review? |
|---|---|
| New attached ADU | Yes |
| New detached ADU | Yes |
| ADU inside the house or an existing accessory structure | No |
| Garage converted to an ADU | No |
Source: Del Mar ADU Application Packet, Engineering ADU Plan Requirements.
How proportional impact fees work
The HCD handbook's example: a 1,000 sq ft ADU next to a 2,000 sq ft house could be charged 50% of the impact fee for a new house. Under 750 sq ft, nothing. A JrADU is exempt at 500 sq ft or less. Connection fees or capacity charges, where they apply, must be proportionate to the ADU's size or drainage fixture units compared with the house.
Soft costs the packet adds
- A preliminary title report dated within six months of submittal
- A licensed plumber's video and certification of the existing sewer lateral
- A Standard Project Stormwater Management Plan and BMP site plan
- An erosion control plan on site between October 1 and April 30, unless waived
- A 24 by 36 in site plan at 1 in = 10 ft, with easements and trees 4 in or larger
Cost checklist
- Conversion or new construction?
- Under 750 sq ft?
- Sewer lateral sound, or replacement needed?
- Any right-of-way work (driveway, pavers)?
- Within a FEMA flood zone (elevation certificate)?
Also checked Oct 14, 2026: Del Mar ADU Application Packet (Rev. 2024) · HCD ADU Handbook (March 2026).
Sources, checked Oct 14, 2026: Del Mar FY 2027 Engineering and Planning fee schedule · Del Mar Municipal Code Chapter 30.91 (June 2025).
Questions
What are Del Mar's ADU permit fees?
For FY 2027, the Planning ADU fee is $1,227 and Engineering ADU review and inspection is $771 for one cycle, with $534 per additional review.
Are there impact fees on a Del Mar ADU?
Not on an ADU of 750 sq ft or less under state law; above that, fees are proportional to the house's size, per the HCD ADU Handbook.
Do school fees apply to ADUs?
School districts may levy fees on ADUs over 500 sq ft of interior livable space; smaller units aren't subject to school fees, per the HCD handbook.