Fast, Reliable New Detached ADU Across Los Gatos
A new detached ADU in Los Gatos typically costs between $280,000 and $450,000 all-in, from the first geotechnical report through final inspection. That’s a wide range because Los Gatos is two different towns on one map: flat valley-floor lots where a standard 600-square-foot studio ADU is straightforward, and hillside parcels off Kennedy Road or in the Glenridge area where Chapter 7A fire construction and engineered foundations are mandatory. Either way, you get one written price before we order a single finish item. That’s how we’ve done 900+ ADUs since 2015, and it’s how every Los Gatos project starts. Call (971) 497-2402 for a free estimate, and we’ll walk you through the actual sequence for your specific lot.
Most Los Gatos homeowners we meet have already spent weeks researching. They know the difference between a permitted addition and an unpermitted one. What they want is the order of operations: geotech first, fire-rated materials locked, custom lead times confirmed, then a written price that holds. That’s exactly what this page covers, for your specific hillside or your specific flatland block.
Why Ellery ADU Studio Is Los Gatos’s Preferred New Detached ADU Company
We design, permit, and build under one contract. No designer blaming the builder. No builder blaming the drawings. One written price, one team, one permit set. In Los Gatos, that matters more than almost anywhere else in the Bay Area, because the town’s Community Development Department has specific triggers: geotechnical reports on hillside work, Chapter 7A compliance on mapped Very High Fire Hazard Severity Zones, and a completeness review that will bounce an application missing a soils report. We know which Los Gatos lots will trigger those requirements before you spend a dollar.
Nadia Ellery has run this studio since 2015, the year California’s ADU permitting shifted and detached units became legal statewide. Since then we’ve specified and coordinated prefab systems from Abodu, Cover, and Dvele on Los Gatos hillsides, and built fully custom detached ADUs on the flatland ranch lots near downtown. The difference is documentation: every project gets a permit set, a photo record, and a written warranty under The Haven Standard. Not a summary of how it went. Evidence.
Crews serve Los Gatos locally, with dispatch and scheduling coordinated from our San Francisco Bay Area office. A live person answers calls 24 hours a day at (971) 497-2402. No callback roulette.
Our New Detached ADU Services in Los Gatos
We handle the full scope: New Detached ADU design and construction, from first site walk to final inspection. Here’s how that breaks down in Los Gatos specifically:
Custom Built ADU
A custom detached ADU in Los Gatos is for clients who want architectural glass, millwork built to the cabinetmaker’s lead time, and a footprint that fits a specific yard. The flatland lets us place a 1,200-square-foot two-bedroom on a 45-foot lot. The hillside is a different conversation: slope setbacks, foundation piers, and fire-mandated exteriors. We’ve coordinated custom units off Kennedy Road where the design started with a geotech report and worked backward from there.
Prefab ADU Installation
Prefab systems like Dvele, Abodu, and Cover work well on Los Gatos hillsides where weather windows are short and stick-built framing would stretch into winter fog. We specify the envelope, coordinate the foundation and utility runs, and handle the Chapter 7A finish details that often get missed: ember-resistant vents, Class A roofing, ignition-resistant cladding. The factory builds the box; we make sure the town accepts it. One contract, one written price.
Modular ADU
Modular ADUs in Los Gatos can be faster to permit once the site work is done, but the site work is never free. Long utility runs on hillside lots, trenching through decomposed granite, and sewer connections on legacy systems all shape the price. We give you a line-item scope with a locked price before the modules are ever ordered. That’s Haven Standard Clause 1: written price before any work starts.
Studio ADU & 2-Bed ADU
A studio ADU in Los Gatos generally runs $280,000 to $350,000 complete. A two-bedroom runs $380,000 to $450,000. On a flat lot near downtown, those numbers hold tight. On a hillside lot, the geotechnical report, Chapter 7A materials, and foundation work add $25,000 to $60,000. We tell you that before you sign anything, and the number doesn’t move once you do. No change orders, no re-pricing at inspection stage.
Trusted Brands We Service in Los Gatos
We specify and coordinate materials from James Hardie for fiber-cement siding that satisfies Los Gatos’s wildfire construction triggers, and prefab structural envelopes from Dvele and Abodu where the hillside site demands it. We don’t stock parts; we lock lead times. For a Los Gatos client, that’s the difference between a one-off walnut vanity arriving in six weeks or twenty. We order only after the written price is signed, and we order to the schedule, not to the hope.
Common New Detached ADU Problems We See in Los Gatos Homes
- Hidden conditions in older detached garages and carriage structures. The downtown blocks are full of 1910s-1940s Craftsman bungalows and Victorian cottages where an old garage looks perfect for conversion but conceals knob-and-tube wiring, galvanized supply lines, or asbestos board siding. We find it in the pre-construction review, not mid-demo.
- Missed Chapter 7A triggers. Los Gatos hillside lots in mapped Very High Fire Hazard Severity Zones require Class A roofing, ember-resistant vents, and ignition-resistant cladding. We see plans bounced back weeks after submittal because someone specified combustible soffit vents or wood siding instead of Vulcan venting and fiber cement.
- Custom lead times nobody locks. A Zola window size change made after material orders are placed, or a custom cabinetry decision that waits until framing starts, doesn’t cost the client a little extra. It costs the client a three-month schedule slip. We pin every finish item lead time before the contract is signed.
- Slope work that wasn’t priced. Hillside lots off Bear Creek Road or in the Summit area often need engineered foundations, retaining walls, and utility runs that flatland projects never see. If the first price doesn’t include a geotech report, the second price will. We include it from the start.
Pricing for New Detached ADU in Los Gatos, CA
Here are the actual numbers we quote at Ellery ADU Studio, as of this writing, for complete permits-through-final-inspection projects in Los Gatos:
- Studio ADU (500-600 sq ft): $280,000-$350,000 flatland; $310,000-$395,000 hillside with Chapter 7A and geotech.
- 1-Bed ADU (600-800 sq ft): $320,000-$390,000 flatland; $355,000-$430,000 hillside.
- 2-Bed ADU (900-1,200 sq ft): $380,000-$450,000 flatland; $420,000-$510,000 hillside.
- Prefab/Modular ADU (Dvele, Abodu, Cover): $290,000-$410,000 depending on envelope, foundation, and Chapter 7A finish package.
What moves the number in Los Gatos: geotechnical work on slopes (adds 6-10 weeks and $5,000-$9,000 before a design revision), fire-rated exterior assemblies, long utility runs on hillside parcels, and the custom millwork and architectural glass tier. What doesn’t move it: our written price. Clause 1 of The Haven Standard locks the scope at signing. Call (971) 497-2402 for a free estimate with a written line-item breakdown.
We Also Serve Cities Near Los Gatos
Our crews work throughout the West Valley: Saratoga, Campbell, Cupertino, and Santa Clara. Flatland projects in those cities don’t carry the same FHSZ and geotech triggers as Los Gatos, but the written-price guarantee, photo record, and 365-Day Done Right Promise apply everywhere we work. See our New Detached ADU in Los Gatos page for the full local breakdown.
Serving Los Gatos, CA - Our Local Coverage Area
We’re based in the Los Gatos area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs - New Detached ADU in Los Gatos
Yes, in most hillside cases. Los Gatos’s Community Development Department will not deem an ADU application complete on a hillside parcel without a soils and geotechnical report stamped by a licensed engineer. That report typically adds 6 to 10 weeks and $5,000 to $9,000 to the project before a single design revision is made. We schedule this first, so the timeline and the price are on the table from day one. Call (971) 497-2402 and we’ll tell you whether your specific parcel will trigger this.
No. Only parcels in the mapped Very High Fire Hazard Severity Zone, which covers much of Los Gatos’s hillside residential land abutting the Santa Cruz Mountains, must meet California Chapter 7A. That means Class A roofing, ember-resistant vents, and ignition-resistant exterior cladding. Flatland neighborhoods near downtown generally don’t trigger this. We check the FHSZ map for every Los Gatos lot before we specify a single material.
Custom cabinetry from shops like Veinte runs 16 to 20-plus weeks, and one-off architectural glass or steel doors can run 20 weeks or more. Flatland projects with standard cabinetry might ship in six weeks. The mistake is ordering without locked lead times, then making a design change after the order is placed. That’s a three-month schedule slip no amount of crew speed can recover. We lock every finish item lead time before the written price is signed.
Because hillside lots in Los Gatos carry risks Campbell flatland projects never encounter: geotech reports, engineered piers, Chapter 7A exterior assemblies, and utility runs through decomposed granite. If those costs aren’t in the first written price, they’ll appear in the second. Under Haven Standard Clause 1, our price is written before any work starts and doesn’t change at inspection. That’s a different contract than most Los Gatos homeowners have ever signed.
No, not if the town inspects it. Los Gatos’s older downtown blocks are full of 1910s-1940s garages and carriage structures where galvanized supply lines and knob-and-tube wiring are still live. A permitted ADU conversion requires bringing that structure to current code: new wiring, new supply lines, seismic and foundation work where needed. We find these conditions during our pre-construction site review, and they’re in the written scope before you sign. Call (971) 497-2402 to schedule a free site walk.
Written by Nadia Ellery, Owner at Ellery ADU Studio, serving Los Gatos since 2015.
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