Frequently Asked Questions - ADU in San Jose, CA
Straight answers to the questions San Jose homeowners ask us most about building an accessory dwelling unit. If you don't see your question here, call (669) 266-4319 and we'll talk it through.
Pricing & Cost FAQs
A detached ADU in San Jose typically runs $180,000 to $320,000, while garage conversions usually land between $120,000 and $200,000. Your actual number depends on square footage, site prep, foundation work, utility connections, and finish level. San Jose impact fees for ADUs under 750 square feet are largely waived, which keeps smaller units more affordable than many homeowners expect. We give every client a written line-item price before any work starts, so you'll know exactly where the money goes. Call (669) 266-4319 for a free estimate on your specific lot.
A garage conversion is almost always the least expensive path, since the foundation, framing, and roof already exist. In San Jose, expect a conversion to run $120,000 to $200,000 depending on how much structural upgrade the existing garage needs. Attached ADUs that convert interior space, like a finished basement or underused family room, can come in lower still. The tradeoff is privacy and rental appeal, which detached units offer in exchange for a higher price. We'll walk you through the numbers for each option on your property before you commit to anything.
No. We give you a written price before any work begins, and that's the price you pay unless you change the scope yourself. The Kingswell Guarantee puts it in writing: say the price before the work. San Jose soil conditions occasionally reveal surprises during excavation, but we handle those conversations transparently with written change orders you approve before we proceed. You will never get a surprise invoice at the end of the job. If you want certainty in your ADU budget, call (669) 266-4319 and ask for a fixed written estimate.
Our estimates are free. We'll visit your property, walk the site, look at your existing structures, and put together a written proposal with a line-item cost breakdown. There's no charge and no obligation. Some San Jose ADU contractors charge a few hundred dollars for feasibility studies, but we believe you should understand your budget before spending anything. To schedule your free estimate, call (669) 266-4319 during business hours: Monday through Friday 7 AM to 7 PM, or Sunday 7 AM to 7 PM.
Adding a bathroom to an ADU plan in San Jose typically adds $25,000 to $45,000 depending on fixtures, tile, and whether new plumbing lines need to run to the structure. The plumbing rough-in is the largest single expense, especially on a detached ADU that sits far from the main sewer line. San Jose permits for ADU plumbing work are folded into the overall building permit, so the paperwork cost stays modest. We include every fixture, line, and connection in your written price, so you'll see the bathroom cost as its own line item before signing anything.
Service & Process FAQs
San Jose processes ADU permits through the city's online portal, and California state law requires the city to approve or deny a complete application within 60 days. Most of our San Jose ADU projects clear permitting in 3 to 6 months, including plan checks and any resubmittals. We handle the entire process: architectural drawings, structural calculations, energy compliance, and submittal to the city. You won't need to chase the planning department. Once the permit is issued, we pull it, post it on site, and schedule inspections as each phase of construction completes.
Most ADU projects in San Jose take 8 to 14 months from first design meeting to final inspection. A garage conversion tends toward the shorter end, around 8 to 10 months, while a ground-up detached ADU typically runs 10 to 14 months including foundation work and utility trenching. San Jose's permit timeline, soil conditions in neighborhoods like Alum Rock and East Foothills, and your finish selections all move the schedule. We give you a written timeline at contract signing and a real arrival window for every phase, so you always know what's happening next.
Most single-family lots in San Jose qualify for at least one ADU under California state law, which overrides many local zoning restrictions. Key factors include setback requirements, lot coverage limits, and whether your property sits in a hillside zone like East Foothills or Portola Valley, where slope and geology add engineering steps. San Jose also allows junior ADUs inside existing homes. The only way to know for sure is a site visit, which costs you nothing. Call (669) 266-4319 and we'll assess your lot against current San Jose ADU standards.
We handle the whole project from first survey to final inspection: design, engineering, permitting, demolition, foundation, framing, roofing, plumbing, electrical, drywall, finishes, and the walkthrough. You deal with one team and one point of contact the entire time. For homeowners in Los Gatos or Milpitas who already have plans drawn, we can also step in for construction only. The Kingswell Way means we show up in the window we gave and leave the place cleaner than we found it, whether we're building from scratch or finishing what another designer started.
Yes. A detached ADU in San Jose gets its own address from the city and its own utility connections, including a separate electrical meter if you want to bill tenants independently. San Jose Water and PG&E both require dedicated service lines for new ADUs, which is part of why site utility work is a meaningful budget line. For attached ADUs, the city still assigns a separate address but utilities may be shared through the main house depending on how the spaces are configured. We coordinate with every utility provider on your behalf.
A junior ADU (JADU) is a unit up to 500 square feet created entirely inside an existing single-family home, often from a bedroom with its own entrance. A full ADU can be attached or detached, up to 1,200 square feet in San Jose, and includes a complete kitchen and bathroom. JADUs may share a bath with the main home under certain conditions. Because JADUs require no new foundation and minimal site work, they can be built faster and cost significantly less. San Jose allows one JADU plus one ADU on the same lot in many cases.
Brands & Parts FAQs
Prefab ADUs from companies like Abodu and Plant Prefab can shorten on-site construction time, but they're not the right fit for every San Jose lot. Narrow access roads in neighborhoods like Burbank or Alum Rock can make crane delivery impractical, and hillside sites in Los Altos Hills usually need a site-built foundation that prefab modules aren't designed for. We can evaluate whether a prefab approach works on your property and coordinate with the manufacturer if it does. For most San Jose lots, a site-built ADU with Hardie siding from James Hardie delivers the best combination of durability and long-term value.
We recommend James Hardie fiber cement siding for most San Jose ADUs because it stands up to our dry summers and wet winters without warping or cracking the way wood siding can. Termites, which are a real concern across Santa Clara County, won't touch it. Hardie plank and panel products also come in styles that match both mid-century ranches in West San Jose and craftsman homes in Willow Glen. It costs more than vinyl up front, but the 30-year expected lifespan and low maintenance make it the best value for a structure you plan to keep for decades.
A Tuff Shed shell is not a legal ADU in San Jose as delivered. California building code requires ADUs to meet the same energy, insulation, foundation, and life-safety standards as a primary dwelling, and stock shed structures do not. However, some homeowners use a Tuff Shed as a starting point for a garden office or storage building that never becomes living space. If you want a legal, rentable ADU, it needs to be designed and built to residential code from the foundation up. We can show you what that difference looks like on your budget.
Licensing & Insurance FAQs
Every pro working under the Lodgewick ADU name in San Jose is required to hold the license and insurance their state requires for residential construction. That means general contracting licensure through the California Contractors State License Board and general liability coverage for the work being performed. Before any job starts, you'll receive documentation of the coverage on your project. Russ Delmar, who leads our San Jose branch, can walk you through exactly what's in place for your specific build. Call (669) 266-4319 and ask.
Yes, every ADU we build in San Jose is fully permitted, inspected, and finalized with the city. We pull the permit, post it on site, schedule every inspection, and make corrections if an inspector asks for them. Unpermitted ADU work is a serious risk in Santa Clara County: when you go to sell, the city can flag the structure and require it to be brought to code, demolished, or legalized at your expense. A permitted ADU also qualifies for the property tax benefits and rental income opportunities that make the investment pay off.
We work with both in-house crews and specialized local subcontractors for electrical, plumbing, and structural work. The standard is the same either way: every pro working under our name is required to hold the license and insurance their state requires, and every crew works to the Kingswell Guarantee. Russ Delmar personally oversees each San Jose job, so whoever is on your site, you have one accountable person who knows your project. If a concern ever comes up, you call one number and it gets handled.
Emergency & Response FAQs
Call (669) 266-4319. Our San Jose team answers during business hours: Monday through Friday 7 AM to 7 PM, and Sunday 7 AM to 7 PM. If you have an active project and something urgent comes up, like a water intrusion during construction or a safety concern on the job site, we'll get the right person on it quickly. We don't promise around-the-clock answering because that's not how we operate, but when we're open, a live coordinator picks up and connects you with the local team immediately.
Yes, we take on stalled and abandoned ADU projects in San Jose more often than you'd think. The most common situations we see are homeowners in Fremont or Union City who paid a contractor, got a foundation poured, and then the crew stopped showing up. We'll inspect what's there, identify code issues, and give you a written price to complete the job correctly. You'll know what's salvageable and what needs to be redone before you spend another dollar. Call (669) 266-4319 to have us look at your site.
If a defect shows up inside the guarantee period, we come back and fix it at no charge. That's the Kingswell Guarantee in writing: say the price before the work, show up in the window we gave, leave the place cleaner than we found it, and come back if it fails. We don't make you chase subcontractors or file insurance claims. You call us, we schedule a return visit, and we make it right. It's the reason we put the guarantee in writing on every single job instead of just saying the words.
Warranty & Guarantees FAQs
The Kingswell Guarantee covers four promises on every ADU we build: a written price before any work starts, a real arrival window for every phase, a clean job site every day, and a written guarantee on the work itself. If a covered repair fails inside the guarantee period, we come back and fix it at no charge. The guarantee is in writing, not implied, and it travels with the project. When Russ Delmar hands you the final walkthrough packet, the written guarantee is in there with everything else: permits, warranties, and maintenance notes.
Our workmanship warranty runs a full year from final inspection, and we put it in writing on every San Jose ADU project. Many building components carry longer manufacturer warranties: roofing, siding from James Hardie, windows, water heaters, and appliances all have their own coverage that we document and hand over at closeout. The Kingswell Guarantee means if our workmanship fails inside that year, we come back and fix it at no charge. No arguing, no fine print games. It's the standard every Lodgewick ADU location works to.
Yes. The written workmanship warranty stays with the property, so if you sell your San Jose home during the warranty period, the new owner is covered. We document everything at closeout, including the warranty, permits, and every manufacturer's coverage, so you can hand the whole packet to a buyer. A permitted, warranted ADU is a selling point in this market, where buyers in Fremont and Palo Alto specifically look for properties with legal rental units. Ask us for the exact warranty terms when you get your estimate.
Russ Delmar leads Lodgewick ADU San Jose, overseeing every project from first estimate to final inspection. He's the person you'll talk to when you call, and the one accountable if anything needs attention. Russ brings the Kingswell Way to every San Jose job: say the price before the work, show up in the window we gave, leave the place cleaner than we found it, and come back if it fails. Homeowners in San Jose, Milpitas, Los Gatos, and the surrounding communities work with Russ because he does what he says he'll do.
Yes. Lodgewick ADU San Jose serves the broader South Bay and Peninsula: Fremont, Palo Alto, Milpitas, Union City, Los Altos, Los Gatos, Los Altos Hills, East Foothills, Portola Valley, and the Alum Rock and Burbank neighborhoods of San Jose. Each city has its own permitting quirks, and we know them: Palo Alto's design review, Los Altos Hills slope rules, Fremont's school district fees. Wherever your lot sits in the South Bay, call (669) 266-4319 and we'll tell you what applies.
Written by Russ Delmar, Owner at Lodgewick ADU San Jose, serving San Jose and the South Bay since 2010.
Still Have Questions?
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(669) 266-4319