San Mateo County · California
San Carlos ADU guide: local rules, permits & property planning
San Carlos combines a local plan gallery with property-specific checks for trees, sewer work and overlay districts. The gallery is free to browse, while permission to use a designer’s drawings can cost money.
Local planning guide · Reviewed October 2, 2026
What matters for an ADU in San Carlos
Permitting authority: City of San Carlos — Building an ADU
Official local guidanceLocal rules and design checks
| Topic | Local guidance |
|---|---|
| Plan licensing | Obtain the designer’s permission before using a gallery plan. |
| Overlay districts | Ask Planning whether site or overlay standards require changes that affect the preapproved route. |
| Rental term | The City’s guidance prohibits rentals of fewer than 30 consecutive calendar days. |
Selected local requirements, not a complete zoning determination. Confirm the current rules for your address with the responsible agency.
Fees and budget checks
The City distinguishes impact-fee exemptions for units under 750 square feet from utility connection and capacity charges. Use the FY2026–27 City fee schedule and request any tree-protection or sewer-related charges separately.
San Carlos FY2026–27 fees and cost of servicesHow to start the permit process
After obtaining plan-use permission, add site-specific information and submit directly to Building. Identify use of preapproved drawings in the application’s Description of Work.
Plan resource
San Carlos ADU Plans Gallery
The City links reviewed designs and designer contacts. Browsing access does not include a free license to build the design.
View the original sourceSan Carlos ADU questions
- Are the gallery plans free to build from?
- The gallery is free to browse; plan-use permission and pricing come from the designer.
- Does an impact-fee exemption include water and sewer capacity?
- The City expressly distinguishes utility connection and capacity charges from those impact fees.
Sources for this guide
Local sources reviewed October 2, 2026. Historical examples retain their stated dates. Contact ADU California to confirm project availability; this guide does not establish an office location or property approval.
A useful first review
Separate what is available from what still needs verification.
01
Confirm the property
Start with a complete address and review the available parcel, building, and map context.
02
Identify the unknowns
Keep missing setbacks, easements, utilities, access, hazards, and local requirements visible.
03
Choose the next review
Use the preliminary result to prepare a focused conversation with the required professionals and agencies.
Explore project types
Compare the scope before choosing a solution.
These pages explain the questions each project type introduces. They do not assert that a particular scope is permitted or suitable for your address.
Compare planning footprints
See common ADU sizes before choosing a design.
These model pages are planning references only. They are not a statement that a particular size is allowed or buildable at a San Carlos address.
California directory
Explore more city guides.
The next useful action
Put your address at the center of the conversation.
The online review is preliminary and is not a permit decision, survey, engineering opinion, construction document, final price, or guaranteed schedule.