Palo Alto · Zoning · OS
Palo Alto OS zoning: height, setbacks and lot size
In Palo Alto's OS zone, buildings can be up to 25 ft (2 stories) tall, the front setback is 30 ft and the minimum lot size is 10 acres (Palo Alto code, read October 2026).
Key points
- Maximum building height: 25 ft
- Maximum number of stories: 2 stories
- Minimum front setback: 30 ft
- Minimum side setback: 30 ft
- Minimum rear setback: 30 ft
- Minimum lot size: 10 acres
- Maximum floor area ratio (FAR): 6.0% (Residential use on a parcel under 1 acre; larger parcels get lower limits, prorated between sizes.)
OS is a zoning district in Palo Alto. Every value below was read from the Palo Alto Municipal Code and links to its section (read October 2026). State laws such as the ADU and SB 9 rules can allow more on a residential lot. General information, not legal advice — read the code text and check with the city before you build.
Development standards in OS
The general rule for a typical lot in this zone. Zoning tables often attach notes, such as rules for corner lots, lots next to a residential zone, or new subdivisions only. Open “code text” under a value to see the table cell or sentence it was read from.
| Maximum building height | 25 ft See note 5 below the table in the code. § 18.28.050 · code textTable row “Maximum Height (ft)”, column “OS (5)”: 25 Note 5: See Section 18.28.070(r) for specific exceptions to these development standards. |
|---|---|
| Maximum number of stories | 2 stories See note 5 below the table in the code. § 18.28.050 · code textTable row “Maximum Number of Stories”, column “OS (5)”: 2 Note 5: See Section 18.28.070(r) for specific exceptions to these development standards. |
| Minimum front setback | 30 ft See note 5 below the table in the code. § 18.28.050 · code textTable row “Front Setback”, column “OS (5)”: 30 Note 5: See Section 18.28.070(r) for specific exceptions to these development standards. |
| Minimum side setback | 30 ft See note 5 below the table in the code. § 18.28.050 · code textTable row “Interior Side Setback”, column “OS (5)”: 30 Note 5: See Section 18.28.070(r) for specific exceptions to these development standards. |
| Minimum rear setback | 30 ft See note 5 below the table in the code. § 18.28.050 · code textTable row “Rear Setback”, column “OS (5)”: 30 Note 5: See Section 18.28.070(r) for specific exceptions to these development standards. |
| Minimum lot size | 10 acres See note 5 below the table in the code. § 18.28.050 · code textTable row “Site Area (acres)”, column “OS (5)”: 10 Note 5: See Section 18.28.070(r) for specific exceptions to these development standards. |
| Maximum floor area ratio (FAR) | 6.0% Applies: Residential use on a parcel under 1 acre; larger parcels get lower limits, prorated between sizes. § 18.28.050 · code textTable row “< 1 acre”, column “Floor Area Ratio 1 (FAR)”: 6.0% |
When a different number applies
The code sets other values for particular lots, buildings or locations in OS:
- Maximum floor area ratio (FAR): 5.0% — Residential use; parcel of 3 acres. Sizes in between are prorated. § 18.28.050
- Maximum floor area ratio (FAR): 4.0% — Residential use; parcel of 5 acres. Sizes in between are prorated. § 18.28.050
- Maximum floor area ratio (FAR): 3.5% — parcel size > 10 acres; residential use § 18.28.050
- Maximum floor area ratio (FAR): 7.5% — parcel size < 1 acre; residential use; bonus FAR if > 80% of site remains undisturbed and/or is restored with native vegetation § 18.28.050
Not on this page
We did not find a general lot coverage, density limit for OS in the zoning tables we read. The code may still set one elsewhere — check the Palo Alto Municipal Code.
Other Palo Alto zoning districts
Who this affects
Frequently asked questions
What is the maximum building height in Palo Alto's OS zone?
25 ft — Palo Alto Municipal Code § 18.28.050.
What is the maximum number of stories in Palo Alto's OS zone?
2 stories — Palo Alto Municipal Code § 18.28.050.
What is the minimum front setback in Palo Alto's OS zone?
30 ft — Palo Alto Municipal Code § 18.28.050.
What is the minimum side setback in Palo Alto's OS zone?
30 ft — Palo Alto Municipal Code § 18.28.050.
What is the minimum rear setback in Palo Alto's OS zone?
30 ft — Palo Alto Municipal Code § 18.28.050.
General information, not legal advice.
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