Floor area and the 800 sq ft rule
Floor area ratio is the number that decides most Solana Beach ADU sizes. The Solana Beach ADU Submittal Process and Basic Plan Requirements (June 2025) includes the full worksheet.
Maximum floor area by zone
| Lot type | Formula |
|---|---|
| HR and MHR zones | Lot area × 0.75 |
| Scaled Residential Overlay Zone (SBMC 17.48.040) | 0.500 first 6,000 sq ft; 0.175 to 15,000; 0.100 to 20,000; 0.050 above |
| Other residential | 0.600 first 5,000 sq ft; 0.300 to 20,000; 0.150 above |
Exemptions
- ADU: 800 sq ft deducted
- Garage: up to 400 sq ft (200 per qualifying space, two maximum)
The 60% threshold
If total proposed floor area exceeds the 60% DRP threshold, the ADU is limited to 800 sq ft.
Worked example (illustrative arithmetic only)
A 7,000 sq ft lot outside the SROZ: 5,000 × 0.6 = 3,000 plus 2,000 × 0.3 = 600, for a maximum of 3,600 sq ft. Gross versus net lot area is defined in SBMC 17.08.020, so confirm your figures with Planning.
Impact fee link
The site plan must state the ADU's size as a percentage of the house (not counting the garage); staff use it to calculate impact fees.
The code's size caps sit on top of FAR
FAR isn't the only limit. SBMC 17.60.210(A)(3)(g) caps an attached or detached ADU at 850 sq ft for a studio or one bedroom and 1,000 sq ft with more than one bedroom. So a 1,000 sq ft ADU needs two bedrooms as well as FAR room. And the code says FAR, lot coverage and setbacks must still allow an 800 sq ft ADU with 4 ft setbacks if it meets other standards.
| Scenario | Likely ceiling |
|---|---|
| Over the 60% threshold | 800 sq ft (handout worksheet) |
| Studio or one bedroom | 850 sq ft |
| Two or more bedrooms | 1,000 sq ft |
Also checked Oct 14, 2026: SBMC §17.60.210(A) (Ord. 542, 2026).
Sources, checked Oct 14, 2026: Solana Beach ADU Submittal Process and Basic Plan Requirements (June 2025).
FAQ
Does an ADU count toward FAR in Solana Beach?
800 sq ft of the ADU is deducted through the ADU FAR exemption on the city's worksheet.
What is the 60% threshold?
A line on the city's FAR worksheet; if total proposed floor area exceeds it, the ADU is limited to 800 sq ft.
How does the garage exemption work?
Up to 200 sq ft per garage parking space, two spaces maximum, if each space is at least 9 by 19 ft and clear, including of door swings.