Los Gatos / ADU construction
ADU Construction in Los Gatos
Los Gatos adds 10 percent floor area for an ADU. The trees and the hillside decide where it goes.
The Town of Los Gatos gives ADUs a floor area bonus, exempts them from lot coverage and reviews them through one streamlined application. We design and build ADUs here, starting with what the Town's other rules protect: oaks, historic homes and the fire hazard zones on the hillsides.
LOS GATOS AT A GLANCE
How the Town handles ADUs.
Los Gatos is a town with its own Community Development Department, older homes downtown and hillside lots in fire hazard zones. Each of those changes where an ADU fits and how it is built.
- 1972
- median year a Los Gatos home was built
- 71%
- of homes built before 1980
- 32,786
- residents, ACS 2020 to 2024 estimate
Planning
Planning Division
Answers questions on ADU and JADU rules, which are in Division 7 of Chapter 29 of the Town Code. The Town was updating its ADU ordinance in 2026, with Planning Commission review on June 10.
(408) 354-6874ADU information ↗Los Gatos: accessory dwelling unit information and summary handout ↗Building
Building Division
ADUs go through the Town's portal as one application and one plan review. Submittals are digital only, never by mail or courier, and inspections must be requested by noon for the next business day.
(408) 354-6876Building Division ↗Historic
Pre-1941 homes and five districts
Almond Grove, Broadway, Fairview Plaza, University/Edelen and the Downtown Commercial district are historic districts, and any primary structure built before 1941 may be historic.
What is a historic resource ↗Utilities
PG&E plus SVCE
PG&E delivers electricity and gas, and Silicon Valley Clean Energy supplies the electricity. The Town allows an ADU to have its own utility meters.
WHAT THE TOWN ALLOWS
One ADU, one junior ADU.
On a single-family lot, Los Gatos allows one ADU and one junior ADU. The ADU can reach 1,200 square feet, is exempt from lot coverage, and up to 800 square feet of it is exempt from floor area limits. The Town also adds 10 percent to the allowed floor area ratio, usable only for the ADU.
Detached ADU
Up to 1,200 square feet and 16 feet high, one story, with 4 foot side and rear setbacks and 5 feet from other structures.
Attached ADU
Its own entrance, and an interior connection to the house is allowed. Not in front of or on the second story of a historic home.
Over the garage
In the R-1, R-D, R-M, RMH and R-1D zones, an ADU can go above an existing one-story accessory building when the house is two stories.
Junior ADU
Up to 500 square feet inside the home or attached garage. The owner lives on site, recorded in a deed restriction.
Conversions
Existing space that does not meet setbacks for new construction only needs to meet setbacks for fire safety.
Hillside and rural lots
In the HR and RC zones, a detached ADU can be built in front of the main house, where everywhere else it cannot.
TOWN ADU STANDARDS
ADU or junior ADU.
A junior ADU is cheaper to permit and has no parking requirement, but it must stay inside the house and the owner must live on the property.
| ADU | Junior ADU | |
|---|---|---|
| Maximum size | 1,200 sq ft | 500 sq ft |
| Location | Detached or attached | Inside the home or attached garage |
| Floor area ratio | 800 sq ft exempt, plus a 10% FAR bonus | Counts toward FAR |
| Parking | One space, with exceptions | None |
| Owner occupancy | Not required | Required |
| Impact fees | Traffic Impact Fee at 750 sq ft or more | Exempt |
Source: Los Gatos: accessory dwelling unit information and summary handout ↗
WHAT SLOWS ADUS IN LOS GATOS
Problems Los Gatos owners run into, and how we plan around them.
From Town handouts, state review of the Town's ordinance and the Town's fire and tree rules.
The best spot for the ADU is under a large oak.
Oaks, buckeyes and madrones 24 inches or more in trunk diameter are large protected trees, so an arborist maps them before the footprint is set.
The lot is in a Very High Fire Hazard Severity Zone.
The Town notes that a large portion of Los Gatos is in a Very High Fire Hazard area, so ignition-resistant construction is specified from the first drawing.
The main house is pre-1941, and the ADU was planned in front.
Historic status is checked first, since an ADU cannot go in front of or on the second story of a historic home.
Town and state rules seem to disagree.
California's housing department found parts of the Town's 2020 ordinance out of step with state law in 2023, so we design to the stricter reading and confirm with Planning.
Plans were sent by courier and never logged.
The Building Division accepts submittals only through its online portal, so every package goes in digitally.
Sources: losgatosca.gov ADU handout, Building Division and PSPS pages, Town arborist report standards; HCD letter to Los Gatos, October 27, 2023.
Planning the work
How a Los Gatos ADU gets built.
Site check
Free visit. Protected trees, fire hazard zone, slope, historic status of the house and utility routes.
Design
Plans drawn to Town standards, with an arborist report where protected trees are near the work.
Single application
ADU and JADU application and plan review through the Town's portal, with PG&E service filed alongside.
Build and final
Tree fencing up before work, inspections booked by noon the day before, then occupancy.
BEFORE YOU APPLY
What to settle before drawing a Los Gatos ADU.
Site questions
- Is the house built before 1941, or in a historic district?
- Are protected trees within the work area?
- Is the lot in the hillside area or a fire hazard zone?
- Which zone is it: R-1, HR, RC or another?
Documents to gather
- Completed ADU/JADU application from the Town
- Plan set as one bookmarked PDF signed by the designer
- Arborist report and tree protection plan, where trees are affected
- PG&E service application for the new load
Expect a longer path when
- A protected tree has to be removed
- The work changes the exterior of a historic home
- The ADU is 750 sq ft or more and owes the Traffic Impact Fee
- A new house and a detached ADU are built together
How big can an ADU be in Los Gatos?
Up to 1,200 square feet under the Town of Los Gatos ADU standards. An ADU of up to 800 square feet is allowed regardless of floor area limits, and a junior ADU is limited to 500 square feet inside the home. ADUs are also exempt from lot coverage standards.
How tall can an ADU be in Los Gatos?
16 feet for most ground-floor ADUs in Los Gatos, and 25 feet for an ADU added to the second story of an existing two-story home. ADUs must be one story, except one built above an existing one-story accessory structure on a two-story property in certain residential zones.
Does an ADU in Los Gatos need a parking space?
Yes, one space per ADU, unless an exception applies. The space can be in a front or side setback on a driveway or in tandem, and spaces lost when a garage is converted do not have to be replaced. Exceptions are listed in Town Code section 29.10.320(f)(1).
Do I pay impact fees for an ADU in Los Gatos?
No, not for an ADU under 750 square feet or for a junior ADU. ADUs of 750 square feet or more pay the Town's Traffic Impact Fee, charged in proportion to the size of the main home.
Can I build an ADU on a historic property in Los Gatos?
Yes, with limits. An ADU cannot be built in front of, or added to an existing second story of, a historic primary home. Los Gatos treats any primary structure built before 1941 as potentially historic, and accessory structures and ADUs are not reviewed by the Historic Preservation Committee.
Can I rent my Los Gatos ADU on Airbnb?
No. Short-term rentals such as Airbnb and VRBO are prohibited in Los Gatos ADUs approved after February 6, 2018. Long-term rental separate from the main home is allowed, but the ADU cannot be sold separately.
