Building permits, zoning and land rules in Los Altos, California

At a glance

Building permit

Ask the Los Altos Building Division; the exact citywide requirement and exemptions could not be confirmed³

Building code

Los Altos has adopted the California Residential Code with local amendments²

Zoning

Administered by the City of Los Altos inside city limits¹

R1-10 minimum lot

10,000 sq ft; 11,000 sq ft for corner lots and 15,000 sq ft for flag lots⁶

Septic

County Environmental Health handles onsite wastewater where public sewer is unavailable⁴⁵

RV living

Private-land occupancy could not be confirmed; California generally limits RV occupancy unless local rules allow it⁷

Owner-builder

A state contractor-license exemption may apply, but building permits and inspections still apply⁸

Who to call

Contact details are copied from each office’s official page and were checked against it on October 10, 2026.

Do you need a building permit in Los Altos, California?

California generally requires a separate permit from the building official before a building or structure is constructed, altered, repaired, moved, improved, removed, converted or demolished.⁹ Los Altos has adopted the California Residential Code for residential construction inside the city.² The reviewed material does not establish the complete Los Altos permit requirement or its exemptions, so confirm the proposed scope with the City of Los Altos Building Division before work begins.³

Do not use Santa Clara County's unincorporated-area building rules for an address inside Los Altos. The county directs owners of property within a city to that city's planning department for zoning and development information.¹⁰ An owner-builder may qualify for California's contractor-licensing exemption, but that exemption does not remove building-permit or inspection requirements.⁸

Who handles building permits and zoning in Los Altos?

The City of Los Altos Building Division is the contact for building-permit questions and city building-code administration.³ Call 650-947-2752 or visit 1 N San Antonio Road, Los Altos, CA 94022.³ The city also provides an online permit portal.³

The Los Altos Planning Division handles city zoning, land-use, design and environmental review.¹¹ Call 650-947-2750 or contact the planning counter online.¹¹ The Planning Division accepts electronic applications and answers general zoning questions by phone, email or virtual appointment.¹¹ These city offices are the correct starting point for land inside Los Altos; Santa Clara County Planning and Development administers zoning and building permits only in unincorporated areas.¹²¹³

Does Los Altos have zoning, and what does it mean for lot size?

Los Altos administers its own zoning and land-use program, and its public map provides zoning, land-use and parcel information.¹ Start by identifying the parcel's city zoning district; dimensional standards should not be borrowed from a neighboring district or from unincorporated Santa Clara County.

In the Los Altos R1-10 single-family district, the minimum site area is 10,000 square feet, increasing to 11,000 square feet for a corner lot and 15,000 square feet for a flag lot.⁶ Those figures answer only the R1-10 lot-area question, not setbacks, coverage, height or whether a particular use is allowed. Ask the Los Altos Planning Division for the parcel's full development standards before relying on a house layout or purchase contingency.¹¹ The reviewed material does not confirm a citywide minimum dwelling size or a general agricultural exemption.

How do septic permits work inside Los Altos?

Los Altos generally prohibits sewage disposal from a building by means other than public sewer connection, except as the city sewer chapter provides.⁵ Where public sewer is unavailable and an onsite wastewater treatment system is allowed, Santa Clara County Environmental Health issues permits for new systems and repairs and conducts installation inspections.⁴¹⁴

Call the county Land Use Program at (408) 918-3400 or visit 1555 Berger Drive, Building #2, Suite 300, San Jose, CA 95112.¹⁵ The complete Los Altos rule for authorizing a private sewage-disposal system could not be confirmed, so obtain a city answer on sewer availability and a county answer on onsite-system feasibility before treating septic as an option. Countywide, only 1% of mapped soils are rated without severe limits for a conventional septic drain field, making parcel-level testing especially important.¹⁶

Can you live in an RV or tiny home in Los Altos?

Los Altos prohibits camping on public property, including streets, rights-of-way, parks and other city property.¹⁷ That public-property rule does not answer whether an RV may be occupied on a private residential lot, and we could not confirm a Los Altos private-land rule. California guidance says RVs are not intended as permanent dwellings and generally may be occupied only in mobilehome or special occupancy parks unless a local ordinance allows otherwise.⁷ Ask the Los Altos Planning Division for a written, parcel-specific answer before relying on an RV during construction or as housing.¹¹

A tiny home in California must qualify and be approved under a recognized housing or vehicle classification, and its location must be legal for that classification.¹⁸ The reviewed material does not confirm Los Altos-specific tiny-home occupancy or minimum dwelling size, so the state classification alone is not site approval.

Building a home in Los Altos: the steps in order

1. Confirm that the parcel is inside Los Altos and ask the Planning Division for its zoning district, allowed residential use and applicable dimensional standards.¹¹¹
2. If the parcel is in R1-10, test the proposal against that district's lot-area rule; other districts require their own standards.⁶
3. Resolve wastewater before final design: determine whether public sewer serves the site and, if an onsite system may be allowed, contact Santa Clara County Environmental Health.⁵¹⁵
4. Prepare plans to the residential code adopted by Los Altos and ask the Building Division which building permits, reviews and fees apply.²³
5. Submit through the city's permit system and complete the inspections the Building Division requires; the general Los Altos inspection sequence could not be confirmed.³
6. Obtain final city approval before occupancy and keep approvals for the property record.⁹

What should you check before buying land in Los Altos and Santa Clara County?

First confirm the jurisdiction and zoning district, then obtain written answers on the proposed use, setbacks, lot coverage, height and access from Los Altos Planning.¹¹¹ A county property profile is not a substitute for city zoning information on a Los Altos parcel.¹⁰

Treat wastewater as a purchase contingency if sewer service is uncertain. Los Altos generally expects public sewer, while the county Land Use Program evaluates and permits onsite systems where public sewer is unavailable.⁵¹⁵ Santa Clara County's effective property-tax rate is about 0.7%, and its median annual property-tax bill is about $9,766; both are county-level context rather than a quote for a particular Los Altos parcel.¹⁹²⁰ For any proposed private well, ask the City, County Environmental Health and Valley Water which approvals apply before drilling; a Valley Water permit is required for covered well work within its service area.²¹

Watch-outs

• Santa Clara County's unincorporated building and zoning rules do not govern a Los Altos address; use the city Building and Planning divisions.¹⁰³¹¹
• The R1-10 lot-area figures apply only in that Los Altos district and do not establish setbacks, lot coverage, height or allowed uses.⁶
• Los Altos's public-property camping ban does not settle RV occupancy on a private lot; ask the Planning Division before using an RV as housing.¹⁷¹¹
• A private sewage-disposal option is not automatic: Los Altos generally requires public sewer, and any allowed onsite system goes through Santa Clara County Environmental Health.⁵⁴

Sources

1. Public GIS Viewer (Los Altos), quoted and re-checked
2. 12.08.010 - Adoption of the California Residential Code (Los Altos), quoted and re-checked
3. City of Los Altos Building Division (losaltosca.gov)
4. Onsite Wastewater Treatment System (OWTS), quoted and re-checked
5. library.municode.com (Los Altos), quoted and re-checked
6. 14.06.040 - Site area (R1-10) (Los Altos), quoted and re-checked
7. hcd.ca.gov (California statewide rule), quoted and re-checked
8. California Business and Professions Code Section 7044, quoted and re-checked
9. Do I need a building permit for my project? (California statewide rule), quoted and re-checked
10. Planning Services, quoted and re-checked
11. City of Los Altos Planning Division (losaltosca.gov)
12. Planning Services, quoted and re-checked
13. Apply for a Building Permit, quoted and re-checked
14. Application for septic/OWTS clearance for new development, quoted and re-checked
15. Santa Clara County Department of Environmental Health Land Use Program (deh.santaclaracounty.gov)
16. Share of soils USDA rates "not limited" for a conventional septic drain field (SSURGO). A strict rating: the median county is about 6% and a tenth of counties are 0%, so a low figure means most lots need a site evaluation or an engineered system, not that septic is impossible. Cite it only with that caveat: Bolthole Index county data
17. 9.30.030 - Prohibited camping and storage of property (Los Altos), quoted and re-checked
18. Information Bulletin 2016-01: Tiny Homes (California statewide rule), quoted and re-checked
19. Effective property tax rate: Bolthole Index county data
20. Median property tax bill: Bolthole Index county data
21. Well Permits and Inspections, quoted and re-checked

Written October 10, 2026 from the rules quoted below, each taken from an official source and re-checked by an independent reviewer. This is research, not legal advice: rules change, so confirm with the office before you buy or build.