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Permit guides

ADU Permits in Los Gatos: a Homeowner's Guide

What you can build, which permits you need, and how the review actually works — in plain language.

Last updated October 2026. Rules change; always confirm current requirements with the city or county before you build.

Who handles your permit

The Town of Los Gatos Community Development Department at 110 E Main Street, Los Gatos, CA 95030. Everything starts on the Town's Citizen's Portal (permits.losgatosca.gov) — register for an account first and have a permit technician approve it. Submittals go through a building preapplication, which is a preliminary review before the full permit. The Town does not accept submittals by mail or courier, and plan-check fees come after the preapplication stage.

What you can build

Los Gatos adopted its ADU ordinance (Ordinance 2307) in 2020, and its FAQ spells out the local numbers:

ADUs are exempt from the zone's lot coverage limits. One parking space is required per unit unless the ADU is within a half-mile of a transit stop. There is no preapproved ADU plan library — every unit needs a custom plan set.

Los Gatos: size depends on your lot — ask planning first

Allowable ADU floor area is calculated from lot size, so planning staff should be consulted before you design: lots between 5,000 and 30,000 square feet in the flat zones (R-1, R-D, R-M, R-1D) get an additional 800 to 1,200 square feet. Hillside lots in the HR and RC zones fall under the Hillside Development Standards and Guidelines, with tighter rules. Two hard placement rules: a detached ADU may not sit in front of the primary dwelling, and no ADU may be built in front of a primary dwelling that is a historic resource.

What goes into the submittal

• Completed permit application — uploaded to the preapplication, plus the plan set as one bookmarked PDF signed by the design professional.
• Supporting documents as separate uploads — structural calculations, Title 24 energy forms, soils or arborist reports where applicable.
• Cover sheet details — the current California Building, Electrical, Plumbing, and Fire Codes plus the Energy Code, construction type, occupancy class, sheet index, and a concise scope of work.
• BASMAA "Blueprint for a Clean Bay" sheet — stormwater management is a required plan sheet.
• If planning review came first — the Planning Department approval letter and conditions of approval affixed to the first plan sheet, with a compliance memorandum showing how the conditions are addressed.
• Tree removal permit — apply to the Parks and Public Works Department before the building permit if the project removes or relocates trees.

Where applications usually get stuck

• Incomplete preapplications. A missing plan-check fee payment or an item left off the checklist means the application isn't accepted.
• Wrong floor-area math. Designing to 1,200 square feet on a lot where the zone and lot-size calculation allow less.
• Hillside lots. HR and RC zone parcels trigger the Hillside Development Standards and Guidelines — grading, drainage, and design review add rounds.
• Historic resources. A historic main house limits where the ADU can go, and design review expectations are higher.
• Trees. Los Gatos takes trees seriously; the arborist report and tree permit have to be in order before the building permit moves.