Los Altos · Zoning · R1-20
Los Altos R1-20 zoning: height, setbacks and lot size
In Los Altos's R1-20 zone, buildings can be up to 27 feet (2 stories) tall, the side setback limit is 20 feet and the rear setback limit is 35 feet (Los Altos code, read October 2026).
Key points
- Maximum building height: 27 feet
- Maximum number of stories: 2 stories
- Minimum side setback: 20 feet (interior side yard, first story; on lots under 100 ft wide the R1-10 side yard rule applies instead)
- Minimum rear setback: 35 feet
- Maximum lot coverage: 25%
- Maximum floor area ratio (FAR): 35% (For lots with a net site area not exceeding 11,000 square feet)
R1-20 (R1-20 SINGLE-FAMILY DISTRICT) is a zoning district in Los Altos. Every value below was read from the Los Altos 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 R1-20
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 | 27 feet § 14.10.090 · code textNo structure shall exceed two stories or twenty-seven (27) feet in height from the natural grade. |
|---|---|
| Maximum number of stories | 2 stories § 14.10.090 · code textNo structure shall exceed two stories or twenty-seven (27) feet in height from the natural grade. |
| Minimum side setback | 20 feet Applies: interior side yard, first story; on lots under 100 ft wide the R1-10 side yard rule applies instead § 14.10.080 · code textTable row “First story”, column “Interior side”: 20 feet (25 feet if the height exceeds 22 feet) |
| Minimum rear setback | 35 feet § 14.10.080 · code textTable row “Rear”, column “Rear”: 35 feet |
| Maximum lot coverage | 25% § 14.10.060 · code textThe maximum coverage for all structures in excess of six feet in height shall be twenty-five (25) percent of the total area of the site. |
| Maximum floor area ratio (FAR) | 35% Applies: For lots with a net site area not exceeding 11,000 square feet § 14.10.070 · code textFor lots with a net site area not exceeding eleven thousand (11,000) square feet the maximum floor area shall be thirty-five (35) percent of the net lot area. |
When a different number applies
The code sets other values for particular lots, buildings or locations in R1-20:
- Maximum building height: 20 feet — Flag lots § 14.10.090
- Maximum number of stories: 1 story — Flag lots § 14.10.090
- Minimum side setback: 25 feet — interior side yard, first story, when height exceeds 22 feet; on lots under 100 ft wide the R1-10 side yard rule applies instead § 14.10.080
- Minimum side setback: 25 feet — interior side yard, second story; on lots under 100 ft wide the R1-10 side yard rule applies instead § 14.10.080
- Minimum side setback: 30 feet — Flag lots § 14.10.080
Not on this page
We did not find a general front setback, lot size, density limit for R1-20 in the zoning tables we read. The code may still set one elsewhere — check the Los Altos Municipal Code.
Other Los Altos zoning districts
Who this affects
Frequently asked questions
What is the maximum building height in Los Altos's R1-20 zone?
27 feet — Los Altos Municipal Code § 14.10.090.
What is the maximum number of stories in Los Altos's R1-20 zone?
2 stories — Los Altos Municipal Code § 14.10.090.
What is the minimum side setback in Los Altos's R1-20 zone?
20 feet (interior side yard, first story; on lots under 100 ft wide the R1-10 side yard rule applies instead) — Los Altos Municipal Code § 14.10.080.
What is the minimum rear setback in Los Altos's R1-20 zone?
35 feet — Los Altos Municipal Code § 14.10.080.
What is the maximum lot coverage in Los Altos's R1-20 zone?
25% — Los Altos Municipal Code § 14.10.060.
General information, not legal advice.
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