A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateADU Company in Alum Rock, CA
Adding an accessory dwelling unit (ADU, a secondary home on your existing lot) in Alum Rock means working with steep hillsides, older foundations, and county rules that don’t apply to flatland neighborhoods. Most lots here were platted between 1920 and 1960, when setbacks were loose and grading was minimal, so nearly every project starts with a site evaluation before a single plan gets drawn. Lodgewick ADU San Jose handles that evaluation, the design, and the build under one written price, so you know the full cost before work starts. Call (669) 266-4319 to schedule a free estimate.
Why Alum Rock Homes Are Different
Alum Rock climbs into the Diablo Range foothills, and that changes everything about how an ADU gets built here. Homes off Alum Rock Avenue and in the canyon neighborhoods often sit on lots where the buildable flat area is a fraction of the parcel. Many backyards drop away steeply, and a good number of properties fall inside landslide zones or sit near creek buffers that trigger extra environmental review. We regularly see detached garages from the 1940s and 1950s with foundations that were never engineered for a second story, which means a vertical ADU above a garage usually requires new footings and shear reinforcement first.
The climate shapes the decisions too. Summers run hot and dry against the hills, and fire risk is real, so fire-resistant siding and defensible space around the unit aren’t optional upgrades here, they’re part of getting the permit approved. Winters are mild but wet, and drainage on a sloped lot can turn a small retaining wall error into a foundation problem. The Kingswell Way means we name these issues in the written price before work begins, not after the crew is on site.
Our Main Alum Rock Services
Most Alum Rock homeowners call us for one of three jobs: adding square footage to the main house, converting a detached garage into living space, or building a freestanding ADU. Each has its own Alum Rock page with pricing and details.
Home Addition Contractor in Alum Rock
A home addition (new square footage attached to your existing house) on a steep Alum Rock lot often means terracing the foundation into the hillside. We evaluate the slope, the existing foundation, and the drainage pattern before pricing anything. On homes with non-conforming setbacks, the addition usually has to match the existing footprint rather than extend it, which changes the design early. Read the full breakdown on our Home Addition Contractor in Alum Rock page.
Garage Conversion Contractor in Alum Rock
A garage conversion (turning the garage into a studio or one-bedroom unit) is often the fastest path to rental income in Alum Rock because the structure already exists. The catch is that most garages in the canyon neighborhoods were built before current seismic codes, so expect foundation strengthening, shear walls, and possibly a new roof structure. We price all of that up front, in writing. See our Garage Conversion Contractor in Alum Rock page for specific costs.
ADU Builders in Alum Rock
A freestanding ADU in Alum Rock is a custom site-specific puzzle, not a standard plan dropped onto the lot. Grading, setbacks, fire-resistant materials, and the location of the existing sewer lateral all drive the design. On the steepest lots, the only practical ADU location is above the garage, and we build those vertical additions with terrace walls that step down the hillside. Our ADU Builders in Alum Rock page covers the options and the price ranges.
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.
Brands We Service in Alum Rock
We’ve worked on site with units from Abodu, Cover, and Tuff Shed, and matched James Hardie siding to the fire-resistant requirements in the Alum Rock foothills. When a homeowner asks us to finish or repair a prefab unit, we know how these systems go together, because we’ve put them together. More on the brands we support is on our brands page.
Pricing for ADU Company in Alum Rock, CA
| Service | Typical range in Alum Rock |
|---|---|
| Detached ADU (studio, 400 – 500 sq ft) | $180,000 – $260,000 |
| Detached ADU (1-bedroom, 500 – 700 sq ft) | $220,000 – $320,000 |
| Detached ADU (2-bedroom, 700 – 1,000 sq ft) | $280,000 – $420,000 |
| Garage conversion (studio, 400 – 500 sq ft) | $120,000 – $180,000 |
| Garage conversion (1-bedroom, 500 – 700 sq ft) | $150,000 – $230,000 |
| Garage conversion (2-bedroom, 700 – 900 sq ft) | $190,000 – $290,000 |
| Second-story ADU above garage | $260,000 – $400,000 |
| Home addition (400 – 600 sq ft) | $160,000 – $240,000 |
| Home addition (600 – 900 sq ft) | $210,000 – $330,000 |
| Home addition (900 – 1,200 sq ft) | $280,000 – $440,000 |
Slope is the biggest price driver in Alum Rock. A lot that needs retaining walls, caissons, or a hillside foundation can add $30,000 to $70,000 before any framing happens. Fire-resistant materials and creek-buffer mitigation add more. Whatever the total, it’s the total: Lodgewick provides a written price before any work starts, and that number does not change at the door.
Neighborhoods We Serve in Alum Rock
We work along Alum Rock Avenue, through the canyon communities, and in the flatter pockets near the San Jose border. We schedule estimates and site visits across the area, and our crews stage from the San Francisco Bay Area office with local Alum Rock scheduling.
- Alum Rock Canyon
- Alum Rock Village
- Little Portugal
- East Foothills
- Country Club
We typically respond within one business day for an estimate request anywhere in the Alum Rock area.
Service Area – Cities Near Alum Rock
Lodgewick ADU San Jose serves Alum Rock and the surrounding communities. If you’re nearby, we also work in San Jose, CA, Fremont, CA, Palo Alto, CA, and Milpitas, CA. Each city has its own permitting quirks, and we handle them locally.
Serving Alum Rock, CA - Our Local Coverage Area
We’re based in the Alum Rock 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 Company in Alum Rock
Most detached ADUs take 6 to 10 months from the first site visit to final inspection. Garage conversions run 4 to 7 months. Hillside lots with grading and retaining wall work add time, and county environmental review for creek buffers or landslide zones can extend permit approval. Call (669) 266-4319 for a timeline specific to your lot.
Yes. Every ADU, garage conversion, and home addition in Alum Rock requires permits, and hillside lots often trigger extra review for grading, geology, and fire safety. We pull the permits, coordinate the inspections, and don’t start work until everything is approved. Estimates are free, so call (669) 266-4319 to find out what your property needs.
Yes. That’s the Kingswell Guarantee in plain terms: the price we write down before work starts is the price you pay. If site conditions reveal something nobody could have known without opening the ground, we show you what we found and agree on any change before proceeding. If the work isn’t right within 365 days, we come back and make it right. Call (669) 266-4319 to schedule your free estimate.
What happens when you call
- 1A real person answersNo phone trees - talk to a local adu pro.
- 2You get an upfront price rangeHonest numbers before anyone is dispatched. No surprises.
- 3We come out and measureLicensed & insured, at a time that suits you - the visit and the quote are both free.
- 4You get the price in writingLine-itemed, yours to keep, and nothing starts until you say go.
What Alum Rock Customers Say
"Converted our garage into a rental studio. The crew was respectful of the neighbors and kept the site clean. It's bringing in rent now and paid for itself faster than I expected."
- Grace Yoon"Built a backyard unit for my mother in law. They handled the permits, gave me a real timeline, and stuck to it within a few days. The written price is what we paid, which anyone who's done construction knows is rare."
- Dennis Fairchild"Added a suite for my dad. They walked us through every cost before a hammer swung and stuck to it. The written price is what we paid, no change orders."
- Ingrid Salazar
