A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateFast, Reliable ADU Builders Across Los Altos Hills
Planning an ADU in Los Altos Hills means working around steep slopes, one-acre minimum lots, and a design review process that favors low, quiet structures tucked into the landscape. Most accessory dwelling units here run $350,000 to $650,000 for a custom detached build, while prefab and garage conversion options generally land between $180,000 and $380,000. The single biggest variable isn’t the structure itself, it’s the site work: grading, retaining walls, septic or sewer extensions, and fire-hardening requirements. If you want a real number in writing before any ground is broken, call (669) 266-4319 and we’ll walk the property with you.
We’re ADU Builders who know this town’s hillside lots, its setbacks, and its planning expectations. Los Altos Hills isn’t like building in the flats of San Jose or Milpitas – the topography alone changes how we approach foundations, drainage, and even which prefab manufacturers make sense for your parcel.
Why Lodgewick ADU San Jose Is Los Altos Hills’s Preferred ADU Builders Company
Los Altos Hills homeowners tend to ask different questions than folks elsewhere. They want to know whether the design will trigger a geologic review, whether a septic system can handle another bedroom, and whether the ADU will look like it belongs on the property rather than dropped in from a catalog. These are the conversations we have every week in Los Altos Hills.
Russ Delmar leads the Lodgewick team here, and he’s the person who signs the written price before work begins. That’s not a sales gimmick, it’s how we’ve done every project since 2010. No price changes at the door, no “we discovered something” surprises. When we tell a Los Altos Hills homeowner what a detached unit will cost, that number holds.
Every project carries the 365-Day Done Right Promise by name. It’s a written guarantee included with the build: if something isn’t right within a year, we come back and make it right, free. That matters more on a hillside ADU than a flat-lot build – drainage issues sometimes show up months later, after the first heavy winter rain.
ADU Contractor in Los Altos Hills
An ADU Contractor in Los Altos Hills does more than frame walls and pull permits. The role means managing a steep-slope excavation without destabilizing the main house above it, coordinating with the town’s design review process, and often expanding a private septic system before the first foundation pour. A custom detached ADU here typically costs $350,000 to $650,000 depending on size, finish level, and the amount of grading required.
Detached ADU Work
A detached unit on a Los Altos Hills parcel usually means working below or above the main residence, often on a 15 to 30 percent grade. That adds soil engineering, retaining walls, and drainage swales that flat-lot builders never think about. We price those items in the written estimate from day one, not as change orders later.
Junior ADU and Internal Conversions
Not every Los Altos Hills ADU needs to be a separate building. A Junior ADU, or JADU, converts existing space inside the home – a finished lower level, a wing over the garage, or a large bonus room – into an independent unit with its own bath and kitchenette. These run $120,000 to $220,000 in Los Altos Hills because they usually don’t require septic expansion or major site work, though the design review still applies.
ADU Design in Los Altos Hills
ADU Design in Los Altos Hills isn’t just about square footage, it’s about making a new structure feel inevitable on a particular hillside. The town’s review standards emphasize low-profile rooflines, natural materials, and minimal visual impact from the road and from neighboring parcels. A well-designed ADU here should look like it grew out of the landscape, not like a second house was squeezed onto the lot.
Site Planning and Grading
Most of the design work on a Los Altos Hills ADU happens before the first elevation drawing is finished. We study where the slope breaks, where water moves in winter, where the sun hits in summer, and where the septic tank sits. Those four factors shape the building footprint more than any aesthetic preference.
Prefab and Modular Design Options
A prefab ADU from Abodu or Cover can be a smart fit for Los Altos Hills because the factory build reduces on-site construction time on difficult terrain. Design work still happens locally: foundation engineering, setbacks, utility runs, and exterior finishes all need town approval. A prefab installation in Los Altos Hills typically runs $180,000 to $320,000 including site work and connections.
Trusted Brands We Service in Los Altos Hills
We work regularly with prefab manufacturers including Abodu and Cover, and we build with James Hardie siding for its fire-resistant performance on wooded Los Altos Hills lots. Having hands-on familiarity with these systems means we can give you a realistic cost and timeline instead of a guess. We also carry the trim, flashing, and connection materials these builds need locally, so Los Altos Hills projects don’t stall waiting on parts from out of state.
Common ADU Builders Problems We See in Los Altos Hills Homes
- Septic system capacity hits the wall. Many Los Altos Hills properties run on private septic, and adding a second dwelling pushes a system that was sized for a 1970s household. Expansion or replacement can add $40,000 to $80,000 before construction even starts.
- Steep-slope drainage fights the foundation. Winter runoff on hillside lots finds the new building’s foundation quickly. Without proper swales and sub-surface drains, you’ll see moisture in the unit within two years.
- Design review rejects a generic plan. The town wants ADUs that read as secondary buildings, not competing houses. Plans that pass in San Jose often come back with notes in Los Altos Hills about roof massing and window placement.
- Fire-hardening requirements add complexity. Wooded areas in Los Altos Hills fall under stricter defensible-space and material standards. Siding, vents, and decking choices all affect what the town will approve.
Pricing for ADU Builders in Los Altos Hills, CA
A custom detached ADU in Los Altos Hills runs $350,000 to $650,000, depending on size, slope, septic capacity, and interior finish. Garage conversions here typically range from $180,000 to $300,000, while a Junior ADU inside an existing home falls between $120,000 and $220,000. The three biggest cost drivers are site grading, septic or sewer work, and the town’s design review timeline. Every estimate we give is a written, line-item price before work starts. Call (669) 266-4319 for a free estimate on your Los Altos Hills property.
We Also Serve Cities Near Los Altos Hills
Our crews build ADUs across the neighboring communities, including San Jose, Fremont, Palo Alto, and Milpitas. If your project is in Los Altos Hills proper, we’re on site regularly and know the local review process well. For larger jobs that grow beyond an ADU, our Home Addition Contractor in Los Altos Hills service handles full-scale additions, and our Garage Conversion Contractor in Los Altos Hills team specializes in turning underused garages into rentable space. Serving Los Altos Hills is what we do, every week, on real hillside lots with real hillside problems.
Serving Los Altos Hills, CA - Our Local Coverage Area
We’re based in the Los Altos Hills 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 About ADU Builders in Los Altos Hills
After we walk your property and give you a written price, the town’s design review and permitting process typically takes 4 to 8 months in Los Altos Hills, depending on whether your lot triggers geologic or septic review. We start design and site studies immediately while that process runs. Call (669) 266-4319 to get your property on the schedule.
Yes, we regularly build on the steep, heavily wooded parcels east of Highway 280 and along the Altamont Road and La Barranca Road corridors. Our crews are equipped for hillside grading, retaining walls, and crane placement on constrained driveways.
A prefab ADU from Abodu or Cover in Los Altos Hills typically runs $180,000 to $320,000 including foundation, utility connections, and site work. The factory build shortens on-site time, but the steep-slope site preparation and septic or sewer work are the variables that move the final number. We put it in writing before you commit to anything.
No. The written price we give before work begins is the price you pay, unless you change the scope. That’s The Kingswell Guarantee, and it’s a core part of every Los Altos Hills project we build.
If any workmanship issue or material failure shows up within 365 days of completion, we return and fix it at no charge. Hillside drainage and settling are the things we watch closely on Los Altos Hills builds, and those are covered under the written guarantee.
Planning an ADU on a Los Altos Hills lot is a big decision, and you deserve a straight answer about cost, timeline, and feasibility. Call (669) 266-4319 for a free estimate, and we’ll put a real number in writing before you spend a dollar.
Written by Russ Delmar, Owner at Lodgewick ADU San Jose, serving Los Altos Hills and the surrounding communities.
