Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
Before
After
Before
After
Before
AfterFast, Reliable Home Additions & ADU Across Los Gatos
Home additions and ADUs in Los Gatos run $45,000-$130,000 for a room addition and $90,000-$220,000 for a full detached ADU, with the Town’s Design Review, seismic retrofit, and Wildland-Urban Interface code layers adding two to three months of entitlement time before a shovel breaks ground. We’re Barrett & Sons Construction, owned by Tom Barrett, and we’ve been building in this town long enough to know that the permit desk here is a different animal than Campbell or Saratoga. If you’re planning an ADU off Blossom Hill Road or a second-story addition in the Almond Grove, call us at (877) 610-1318 for a free estimate and a straight answer on what your project will actually cost.
Why Barrett & Sons Construction Is Los Gatos’s Preferred Home Additions & ADU Company
We’re the owner-operated alternative to the out-of-town outfits that quote one number on the phone and show up with another. Tom Barrett founded this company in 1998, and his sons run the crews. You’ll see us at the Los Gatos hardware store, at the farmers market on Sunday, and on your street checking a foundation pour. Ask anyone in Los Gatos who has had work done by us, and they’ll tell you the same thing: the price we quote is the price you pay, and every change is a written change order before it happens.
Our Los Gatos customers hire us because we know this town’s permit process cold. The Town’s Design Review board does not rubber-stamp second-story additions or front-façade changes. We build entitlement time into our schedules up front, so you’re not sitting in limbo wondering why your permit is stalled. We also pull permits on every eligible job, and the inspector signs off before we consider the job done. That’s how we’ve kept a strong local reputation here for over 29 years. We publish Tom’s name, address, and license number, so you can look us up before you sign anything.
Our Home Additions & ADU Services in Los Gatos
ADU Design & Permitting
This is where most Los Gatos ADU projects get complicated fast. A detached ADU in the hills of 95033 usually requires a geotechnical report and engineered caisson or grade-beam foundations before the Town will even open a permit file. Our Home Additions & ADU team works directly with the Town’s Building Department to get your plans into review, and we write the entitlement timeline into your schedule so you know when you’ll actually break ground. We do not hand you a vague promise. We hand you a written scope.
Garage Conversion ADU
Converting an existing garage in the 95030 flats is often the fastest ADU path in Los Gatos, but it is not a free pass. If the garage dates to a pre-1940 home, expect the Town to ask for seismic retrofitting on the original structure before approving the conversion. In the WUI zones up in 95033, garage conversions must meet ember-resistant vent, Class A roofing, and non-combustible eave requirements. We’ve done enough of these to know exactly which upgrades the inspector will flag, and we price them in from the start.
New Detached ADU
A new detached ADU in Los Gatos is the most expensive path, typically $90,000-$220,000, and the cost is driven by foundations, not framing labor. Hillside lots in 95033 routinely need caissons, retaining walls, and subsurface drainage management. The Town’s Design Review process applies to any structure that changes your property’s massing, so we coordinate materials and roofline profiles before you buy anything. Our crews have built ADUs from Monte Sereno to the Shannon Road corridor, and we know where the surprise costs hide.
Junior ADU & Interior Conversion
A Junior ADU inside an existing home is the most restrained option in Los Gatos, typically a 500-square-foot conversion within the existing envelope. It avoids a full Design Review hearing in most cases, but it still requires a permit, a separate entrance, and a small kitchenette. In older Victorians and Craftsman bungalows downtown, we often find original unreinforced masonry foundations that need seismic anchor work before the Town signs off. We write that into the scope from day one, so it’s never a surprise at final walkthrough.
What happens when you call
- 1
A real person answersNo phone trees - you reach a local pro.
- 2
You get an upfront price rangeHonest numbers before anyone is dispatched.
- 3
A background-checked tech heads outLicensed & insured, dispatched right away.
- 4
You approve before work beginsNothing starts until you say go.
Trusted Brands We Service in Los Gatos
We install Techo-Bloc and Cambridge pavers on hardscape elements tied to ADU site work, and we use Quikrete bag mixes for small retaining and drainage jobs where a full truck isn’t practical. We keep common materials stocked locally for Los Gatos customers, so small change orders don’t stall your project for a week. For windows and doors, we carry Andersen and Marvin, and we order them early, because custom millwork lead times are the single biggest schedule killer in this town.
Common Home Additions & ADU Problems We See in Los Gatos Homes
- Design Review delay on second-story additions in 95030. A post-war ranch in the flats can get held up for 8-10 weeks while the Design Review board scrutinizes your roofline profile against the neighbors. We draft elevations with that review in mind, so you’re not paying a designer to redo drawings twice.
- Geotechnical surprises in the hills of 95033. An ADU foundation that hits decomposed granite can jump $15,000-$25,000 when the engineer redesigns for caissons. We order a geotech report before we finalize your fixed price, because an allowance that isn’t on paper is a surprise waiting for a date.
- Material lead-time mismatch. Custom millwork and architectural glass ordered after permit approval dump your project into the rainy season, when mountain orographic downpours erode an open foundation trench and force re-grading before the subfloor can be poured. We order long-lead items the week your permit files.
- WUI code conflicts on garage conversions in 95033. The Wildland-Urban Interface requirements add real cost. Ember-resistant vents, Class A roofing, and non-combustible eaves are non-negotiable up there, and the inspector will flag them every time. We price them in up front.
Pricing for Home Additions & ADU in Los Gatos, CA
Here’s what you’re actually looking at in Los Gatos. A home addition runs $45,000-$130,000, a full detached ADU runs $90,000-$220,000, and a garage conversion runs $30,000-$80,000. The spread is driven by foundation engineering, Design Review revisions, and WUI compliance, not by labor rates. In Los Gatos, labor is the reliable part. The hill lots, the historic review, and the wildfire codes are the expensive part. We give you a fixed price in writing before we order a single board. Call (877) 610-1318 for your free estimate.
| Project Type | Price Range |
|---|---|
| Home Addition | $45,000 - $130,000 |
| ADU Construction | $90,000 - $220,000 |
| Garage Conversion | $30,000 - $80,000 |
We also offer a permanent 10% senior and veteran discount, and a free second opinion on any written estimate. If you have a quote from another Los Gatos builder, bring it in and we’ll tell you if it holds up against what the Town will actually require.
We Also Serve Cities Near Los Gatos
If you’re just over the border, we also serve Saratoga, Campbell, Communications Hill, and San Jose. The Design Review rules change as soon as you leave Town limits, so if you’re planning a second-story addition in Saratoga or an ADU in Campbell, we’ll calibrate the timeline to that jurisdiction’s process. Our home base for Los Gatos work is Home Additions & ADU in Los Gatos, and dispatch is coordinated from our San Francisco Bay Area office.
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 - Home Additions & ADU in Los Gatos
It adds roughly 8-10 weeks to your timeline and a minimum of one revision cycle to your architectural drawings. In the Almond Grove, the Town’s Historic Preservation officer reviews materials, roofline profiles, and siding compatibility against the neighborhood’s Craftsman character before permits are issued. We budget for that in writing. Call (877) 610-1318 for an exact read on your street.
Because the decomposed granite and steep canyon slopes up there don’t hold conventional footings, and the Town knows it. We order a geotech report before we write a fixed foundation price, because a foundation redesign to caissons after the fact is a $15,000-$25,000 change order. We won’t have that conversation with you after work starts. It’s in the scope before we dig.
Yes, WUI codes apply in the High and Very High Fire Hazard Severity Zones across upper 95033, and they add roughly $5,000-$10,000 to a garage conversion. You’re looking at ember-resistant vents, Class A roofing, non-combustible eaves, and sometimes tempered glass on the side facing the canyon. We price all of it in the original fixed quote. Call (877) 610-1318 for a line-item breakdown.
Custom millwork in this town runs 8-10 weeks from order to delivery, and it will stall your project if you wait for permit approval to order it. We order long-lead items like Marvin windows, solid-core doors, and custom cabinetry the week your permit files. On a 1920s Craftsman ADU in the Almond Grove, we ordered the windows eight weeks before rough-in because Design Review triggered a materials compatibility check. That’s how we keep your schedule from sliding into the rainy season.
In most cases, yes, if the project stays within the existing garage footprint and doesn’t change the front façade or street-facing massing. Interior conversions in the 95030 flats typically clear at staff level rather than full board review. But if the garage was built before 1940, expect a seismic retrofit requirement on the original structure. We’ll tell you what path applies to your specific property. Call (877) 610-1318 for your free estimate.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Los Gatos and the surrounding Bay Area communities since 1998.