Los Gatos & Monte Sereno · Santa Clara County
ADU Design & Build in Los Gatos & Monte Sereno, California
Los Gatos and Monte Sereno call for homes shaped around mature trees, hillside conditions, distinctive architecture, and the quiet character of each site.
Building ADUs in Los Gatos & Monte Sereno, California
SHAPE designs and builds accessory dwelling units for homeowners in Los Gatos & Monte Sereno, California, across Almond Grove, Glenridge, Blossom Manor, Rinconada, the Los Gatos foothills, and residential streets throughout Monte Sereno.
Los Gatos and Monte Sereno combine established neighborhoods, wooded foothill parcels, and homes with a strong architectural identity. Owners here need detached ADUs, guest houses, and studios that respect the landscape and feel considered alongside the main residence.
We're a licensed California general contractor (CSLB #1158688) with an in-house architecture and modular construction team. That means one contract, one fixed price, and one team responsible from the first site walk through final inspection with the Los Gatos & Monte Sereno building department.
Los Gatos & Monte Sereno ADU Rules at a Glance
- Setbacks: California state law caps rear and side setbacks for new ADUs at 4 feet, and Los Gatos & Monte Sereno follows that standard.
- Height: In Los Gatos, a ground-floor ADU can be 16 feet tall, and a second-story ADU on a two-story house can reach 25 feet. Monte Sereno limits detached ADUs to one story and 16 feet, and attached ADUs to the main house's height, up to 30 feet.
- Maximum size: Los Gatos allows ADUs up to 1,200 sq ft, and up to 800 sq ft of an ADU is exempt from floor area. Monte Sereno allows 1,000 or 1,200 sq ft depending on the zoning district, and an 800 sq ft ADU even on a lot over its coverage limit.
- JADUs: Junior ADUs (up to 500 sq ft) are allowed inside the existing footprint of the primary home, in addition to a detached ADU on most single-family lots.
- Traffic fee (Los Gatos): None under 750 sq ft. Larger ADUs pay a Traffic Impact Fee in proportion to their size.
- Fee discount (Monte Sereno): The city has offered 50% off building permit and plan check fees to its first 225 ADU owners. Ask whether spots remain.
- Pre-approved plans: Both towns have plan galleries. Los Gatos allows no changes to listed plans. Monte Sereno's cannot be used in Wildland-Urban Interface areas.
- Sewer: West Valley Sanitation District serves both towns.
- Parking: No replacement parking is required when a garage or carport is converted or torn down to build an ADU, wherever the lot is. Separately, no parking can be required for the ADU itself within one half-mile walking distance of public transit.
Rules checked September 2026 against: Town of Los Gatos ADU brochure, Town of Los Gatos ADU page, Santa Clara County ADU Resource Center, Monte Sereno, Monte Sereno pre-approved plan requirements, HCD ADU Handbook, California Energy Commission ADU guidance, Santa Clara County Assessor, Santa Clara County ADU Resource Center. City rules change often. We confirm the rules for your lot before design.
SHAPE handles the full permit package with the Los Gatos & Monte Sereno planning department, zoning verification, building plans, Title 24 energy, and every correction cycle, so you don't have to learn the code.
Our Process
- Site assessment. We walk your Los Gatos & Monte Sereno lot, confirm setbacks and utility locations, and give you a feasibility read and an all-in price the same week.
- Design. Our in-house architects design the ADU around your lot, your family, and your budget, with fixed pricing before you sign.
- Permits. We submit, respond to every planning and building comment, and drive the file to permit issuance with Los Gatos & Monte Sereno.
- Build. Modules are fabricated in our facility while site work, foundation, utilities, landscaping, runs in parallel. Set and finish happen on site.
Guest house or ADU in Los Gatos and Monte Sereno?
In Los Gatos, a studio without a kitchen is an accessory building: one story, 15 feet, at least 5 feet from property lines, with limited plumbing, and it counts toward floor area. An ADU gets up to 800 square feet exempt from floor area plus a 10% floor area increase. In Monte Sereno, accessory buildings are for non-dwelling use, and an ADU is larger and taller.
| Accessory building without a kitchen | ADU with a kitchen | |
|---|---|---|
| Los Gatos | One story, 15 feet, counts toward floor area, plumbing limited | Up to 1,200 sq ft, 16 feet, up to 800 sq ft exempt from floor area |
| Monte Sereno (R-1-44) | 1,000 sq ft, 12 feet, 6-foot side and 10-foot rear setbacks | 1,200 sq ft, 16 feet, 4-foot setbacks |
In both towns, an ADU gives you more space and fewer limits than a studio or accessory building.
Hillside lots in Los Gatos and Monte Sereno
Foothill lots in both towns bring tree, fire and access rules that shape the site plan and the budget.
- Trees: Los Gatos protects trees from 12 inches in diameter on developed lots and from 8 inches on hillside lots.
- Fire access: Santa Clara County Fire's standard calls for a fire road within 150 feet of every part of the building, or 200 feet if it is sprinklered.
- Water for firefighting: where there is no adequate hydrant supply, county fire standards can require a private water tank for buildings over 500 sq ft.
- Fire maps: Los Gatos adopted its 2025 fire hazard severity map in June 2025. New ADUs in designated zones follow the 2025 Wildland-Urban Interface Code.
- Monte Sereno pre-approved plans still need a site-specific geotechnical report and County Fire review.
Frequently asked
- How much does an ADU cost in Los Gatos & Monte Sereno?
- SHAPE's published prices start at $223,000 for Model 1, $263,000 for Model 2, and $343,000 for Model 2X on a typical lot. The final fixed quote in Los Gatos & Monte Sereno depends on size, finishes, utilities, access, and site conditions.
- How long do permits take in Los Gatos & Monte Sereno?
- California law requires ministerial ADU review within 60 days of a complete submittal. Real-world timelines in Los Gatos & Monte Sereno typically run 2–4 months including corrections. SHAPE manages every submittal and response with the Los Gatos & Monte Sereno planning department.
- Do I need to add parking for an ADU in Los Gatos & Monte Sereno?
- Often, no. No parking can be required for an ADU within a half-mile walking distance of public transit, and no replacement parking is required when a garage or carport is converted or torn down to build the ADU. We check your lot's distance to transit during feasibility.
- What size ADU can I build in Los Gatos & Monte Sereno?
- Los Gatos allows ADUs up to 1,200 sq ft. Monte Sereno allows 1,000 or 1,200 sq ft depending on the zoning district. On top of local rules, California state law guarantees at least 800 sq ft on most single-family lots regardless of local FAR limits.
- Can I rent out an ADU in Los Gatos & Monte Sereno?
- Yes. California state law allows long-term (30+ day) rentals of ADUs statewide. Short-term rentals are set by the city, Los Gatos & Monte Sereno, like most Bay Area jurisdictions, restricts or prohibits stays under 30 days.
- Can I build a two-story ADU in Los Gatos?
- In one main case: a second-story ADU on a two-story house can reach 25 feet. Otherwise a Los Gatos ADU is generally one story and 16 feet tall.
- What is the Los Gatos traffic fee for an ADU?
- ADUs under 750 square feet pay no impact fees. ADUs of 750 square feet or more pay a Traffic Impact Fee in proportion to the size of the unit.
- Is the Monte Sereno ADU fee discount still available?
- Monte Sereno has offered 50% off building permit and plan check fees to its first 225 ADU owners, which cuts roughly $9,000 to $10,000 in fees about in half. Ask the city whether spots remain, or ask us to check for you.
- My lot is in a fire zone. Can I use a pre-approved plan?
- Not in Monte Sereno's Wildland-Urban Interface areas, where pre-approved plans are excluded. In Los Gatos, pre-approved plans cannot be changed at all, so a hillside or fire zone lot usually needs a custom design.
- Can I build an ADU on any Los Gatos or Monte Sereno lot?
- Yes, on any lot with an existing or proposed single-family home, and state law does not allow a minimum lot size for ADUs. On foothill lots, trees, slope and fire access decide where it can go.
- How many bedrooms can the ADU have?
- State law does not let cities cap the number of bedrooms in an ADU. Size limits and your lot's floor area decide how many fit.
- Does the ADU need solar panels?
- A new detached ADU does. Under the 2025 California Energy Code it needs new solar panels, which can be added to an existing system elsewhere on the property. An attached ADU counts as an addition and does not need solar.
- Does the ADU need its own utility connections?
- Not always. State law bars a separate-connection requirement for ADUs built inside existing space. For a new detached ADU, PG&E, the water company or West Valley Sanitation District can require its own connection, with fees in proportion to the ADU's size. We settle this with each utility during design.
- Will an ADU raise my property taxes?
- Only on the new building. The Santa Clara County Assessor does not reassess the existing home. It assesses the ADU at market value when it is finished, or partly on January 1 if construction is still underway.
- Can I sell the ADU separately?
- No. The Los Gatos ADU rules bar separate sale, and neither town has adopted the state's optional condominium route under AB 1033.
- Can I build the ADU and a new main house at the same time?
- Yes. State law lets the town approve both together, and the ADU is still reviewed without discretionary review. When the two are built together, utilities can treat the ADU as new residential use for connection fees.
- Will an ADU change my home insurance?
- Tell your insurer before the ADU is occupied, because it adds value to cover. In fire hazard areas, California's Safer from Wildfires program requires insurers to offer discounts for measures such as a Class A roof and ember-resistant vents, and a new ADU built to the 2025 Wildland-Urban Interface Code already has both.
- Is the California $40,000 ADU grant still available?
- No. CalHFA's ADU Grant paid up to $40,000 toward predevelopment costs, and CalHFA says its latest round was fully allocated in December 2023. CalHFA warns that anyone offering to get you one is running a scam.
- How long does PG&E take to connect an ADU?
- PG&E reported ADU electric hookups averaging about 300 days from request for projects finished by August 2025, and says its average for new service had dropped to 118 days by March 2026. We file with PG&E when the permit goes in so power is not the last thing we wait on.
Nearby cities we serve
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