Resource guide
Silicon Valley permitting & zoning, explained.
Every city in Santa Clara and San Mateo counties runs its own review process. This guide covers how residential remodel approvals generally work and what's distinctive about each jurisdiction we serve.
How the approval process works
- 1
Feasibility & zoning check
Confirm zoning district, setbacks, floor area and lot coverage limits, height and daylight plane, overlays (single-story, historic, hillside), and whether the parcel is incorporated or unincorporated.
- 2
Planning / design review
Projects like second stories, larger additions, hillside work, or changes to historic properties often need planning approval before a building permit. This may involve neighbor notification, story poles, or a public hearing.
- 3
Building permit plan check
Construction drawings, structural calculations, and energy compliance documents are reviewed by the building department. Expect one or more rounds of comments.
- 4
Permit issuance & inspections
Once approved, the permit is issued and construction proceeds with required inspections — foundation, framing, rough MEP, insulation, and final.
Rules that apply statewide
California Building Standards Code (Title 24)
Every jurisdiction enforces the state building, residential, electrical, plumbing, mechanical, and energy codes, sometimes with local amendments.
Energy code & local reach codes
Title 24 Part 6 sets energy requirements for alterations and additions. Many Silicon Valley cities have adopted reach codes that encourage or require all-electric construction for certain projects.
CALGreen
California's green building code sets requirements for construction waste diversion, water efficiency, and indoor air quality on qualifying projects.
ADU and SB 9 laws
State law streamlines accessory dwelling units and, under SB 9, certain lot splits and two-unit projects on single-family lots — subject to local implementing rules.
Wildfire & hillside standards
Parcels in designated fire hazard severity zones may require ignition-resistant construction and defensible space. Hillside towns often add geotechnical and grading review.
Tree protection
Most cities protect heritage or specimen trees. Work near protected trees may require an arborist report and a tree permit.
Jurisdictions
Santa Clara County
Unincorporated parcels are permitted by the Santa Clara County Department of Planning and Development.
| City / Town | Reviewing department | What to know |
|---|---|---|
| Campbell | City of Campbell Community Development Department | Planning and building permits are handled by the City of Campbell Community Development Department. Larger additions and second stories typically go through site and architectural review. |
| San Jose | City of San Jose Planning, Building and Code Enforcement | Permits are issued by the City of San Jose Department of Planning, Building and Code Enforcement. Some neighborhoods include historic districts or conservation areas with additional design review. |
| Los Gatos | Town of Los Gatos Community Development Department | The Town of Los Gatos Community Development Department reviews projects. Many additions require architecture and site approval; historic districts involve the Historic Preservation Committee, and hillside lots follow the Town's hillside standards. Some areas fall within designated fire hazard zones. |
| Saratoga | City of Saratoga Community Development Department | The City of Saratoga Community Development Department administers design review, which commonly applies to second-story additions and larger projects. Hillside parcels may need geotechnical review and wildfire-related construction standards. |
| Monte Sereno | City of Monte Sereno | The City of Monte Sereno reviews most significant residential projects through its site and architecture review process, with attention to hillside conditions and neighborhood compatibility. |
| Cupertino | City of Cupertino Community Development Department | The City of Cupertino Community Development Department reviews projects. Two-story additions are subject to residential design review, and some neighborhoods have single-story overlay zoning. |
| Sunnyvale | City of Sunnyvale Community Development Department | The City of Sunnyvale Community Development Department reviews permits. Sunnyvale has adopted Eichler design guidelines, and some Eichler neighborhoods have single-story combining districts. |
| Santa Clara | City of Santa Clara Community Development Department | Permits are handled by the City of Santa Clara Community Development Department. Properties in historic areas such as the Old Quad may require additional historic review. |
| Mountain View | City of Mountain View Community Development Department | The City of Mountain View Community Development Department reviews projects. Larger additions and new two-story homes may require development review; some mid-century neighborhoods have specific design considerations. |
| Los Altos | City of Los Altos Development Services | The City of Los Altos Development Services Department reviews projects. Second-story additions and new two-story homes typically go through residential design review. |
| Los Altos Hills | Town of Los Altos Hills Planning & Building Department | The Town of Los Altos Hills Planning and Building Department reviews projects. Development limits often depend on lot size and slope, and site development review is common for additions and grading. |
| Palo Alto | City of Palo Alto Planning & Development Services | Projects are reviewed by the City of Palo Alto Planning and Development Services Department. Second-story additions and new two-story homes generally go through Individual Review; the city has Eichler design guidelines, single-story overlay districts, and historic resource review. |
Jurisdictions
San Mateo County
Unincorporated parcels (for example, parts of Emerald Hills and Ladera) are permitted by San Mateo County Planning and Building.
| City / Town | Reviewing department | What to know |
|---|---|---|
| Menlo Park | City of Menlo Park Community Development Department | The City of Menlo Park Community Development Department reviews projects. Certain two-story projects — especially on substandard lots — may require a use permit, and heritage tree protections are a frequent consideration. |
| Atherton | Town of Atherton Planning & Building | The Town of Atherton Planning and Building Departments review projects. Heritage tree protection, floor area limits, and construction management requirements are common considerations. |
| Portola Valley | Town of Portola Valley Planning & Building | The Town of Portola Valley reviews projects, with many going before the Architectural and Site Control Commission (ASCC). Geologic hazard review and wildfire-resistant construction standards often apply. |
| Woodside | Town of Woodside Planning & Building | The Town of Woodside reviews projects; many go through the Architectural and Site Review Board (ASRB). Rural design guidelines, wildfire standards, and geotechnical conditions are common factors. |
| Redwood City | City of Redwood City Community Development & Transportation | The City of Redwood City Community Development and Transportation Department reviews projects. Note that parts of Emerald Hills are unincorporated and fall under San Mateo County Planning and Building. |
Not sure what your project needs?
We'll review your parcel's zoning and the likely approval path as part of an initial consultation.