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 San Jose
Building an ADU in San Jose is one of the smartest moves a homeowner can make right now, but the process is full of places where a contractor can surprise you with costs you never saw coming. At Lodgewick ADU San Jose, we put every price in writing before we open a single wall. If you’re planning a detached ADU, a garage conversion, or a JADU in San Jose, call (669) 266-4319 for a free estimate. Russ Delmar leads our team, and he’s seen just about every surprise a 1960s San Jose ranch can hide.
Why Lodgewick ADU San Jose Is San Jose’s Preferred ADU Builders Company
Since 2010, Lodgewick ADU Builders has been the ADU arm of the Kingswell family of home-service companies. San Jose homeowners choose us because we operate under The Kingswell Guarantee: a written price before work begins, a defined arrival window, a clean job site, and a written guarantee on every project. If the work isn’t right within 365 days, we come back and make it right. That’s the 365-Day Done Right Promise, and it’s in writing on every build we take on in San Jose.
We know San Jose’s housing stock because we work in it every week. Older ranches in neighborhoods like Cambrian and West San Jose often have 100-amp electrical panels that can’t support a new ADU’s load. We check for that before we quote, not after. When you call, a live person answers 24/7 – never a voicemail loop. That matters when you have a question about your permit status or your crew’s arrival window on a Saturday morning.
Detached ADU in San Jose
A detached ADU in San Jose is a separate, stand-alone living unit built in the backyard of a single-family home, with its own kitchen, bathroom, and entrance. San Jose’s pre-approved ADU plan program can get a detached unit from permit submission to approved in as little as 30 days, which is significantly faster than most Bay Area cities. But those pre-approved plans still require a soils report and shear wall upgrades because the city sits near the Hayward and Calaveras faults.
Seismic Work That Meets San Jose Code
San Jose has stricter seismic requirements than most of California. Out-of-state shear wall details do not fly at the San Jose plan check desk. Our team designs foundations and shear walls to the current California Building Code for this specific fault zone, and we submit plans that pass the first time far more often than not. If a homeowner brings us a set of out-of-state details, we flag it early and redesign before it costs weeks at the permit counter.
Costs for Detached ADUs in San Jose
A detached ADU in San Jose typically runs $180,000 to $420,000 for a complete 400-800 square foot unit, depending on whether you go the prefab route or stick-built. Prefab ADU installation using manufacturers like Abodu, Cover, or Dvele tends to sit in the $220,000 to $320,000 range all-in, including site work, permits, and utility connections. Stick-built units with a custom design, a full kitchen, and high-end finishes start around $280,000 in most San Jose neighborhoods. We write every allowance into the contract so you see the full picture before you sign.
JADU in San Jose
A JADU, or Junior Accessory Dwelling Unit, is a smaller living unit carved out of the existing footprint of your San Jose home, often from a spare bedroom, a garage, or an underused den. JADUs are capped at 500 square feet and can share a bathroom with the main house, which makes them the most affordable way to add rental income or space for a family member in San Jose. Our ADU Builders team handles JADUs as a core part of our work, not an afterthought.
When Older San Jose Homes Need a JADU
In San Jose, JADU conversions make the most sense for homeowners in 1950s-70s ranches where a full detached ADU would eat too much yard. A garage conversion or interior bedroom split can add 400-500 square feet of livable space without touching the setbacks. But here’s what most contractors won’t tell you until the walls are open: those older homes have outdated wiring, shallow sewer laterals, and sometimes asbestos in the original drywall. Our process addresses all of that with allowances written into the contract before demolition starts.
What a JADU Costs in San Jose
A JADU in San Jose typically runs $110,000 to $190,000 when it’s a conversion of existing interior space. Garage conversions to JADUs trend toward the higher end of that range, often $150,000 to $190,000 once you account for plumbing, electrical, and insulation upgrades. Interior bedroom splits are typically lower, in the $110,000 to $140,000 range. Every quote includes a line-item allowance for the unknowns: panel upgrades, sewer work, shear wall additions. You’ll see the number before we start, and any change gets priced and approved in writing before we touch it.
Trusted Brands We Service in San Jose
We work directly with leading ADU brands and materials that perform well in San Jose’s climate and seismic conditions. James Hardie siding holds up through the wet winters and dry summers without swelling or cracking the way wood does. Prefab manufacturers like Abodu and Cover deliver units engineered for California seismic code, which shortens the on-site timeline significantly. For homeowners who want a fully custom stick-built ADU, we source materials locally and keep parts on hand for San Jose jobs, which means fewer days waiting on deliveries. Russ Delmar matches each lot, budget, and timeline to the right manufacturer, and every material choice is documented in the contract.
Common ADU Builders Problems We See in San Jose Homes
- Undersized electrical panels on 1950s-70s ranches. Many San Jose homes in neighborhoods like Willow Glen, Cambrian, and Rose Garden still carry original 100-amp panels. An inspector will not sign off on an ADU or JADU without a 200-amp service upgrade, so we price that allowance into the contract up front.
- Shallow sewer laterals that don’t meet current code. In older parts of San Jose, sewer lines were often buried 14 to 18 inches below grade. Connecting a new bathroom group to a lateral that shallow usually requires trenching and upsizing to a 4-inch line, and we write that as a separate line item you approve before we dig.
- Asbestos in original drywall and flooring. Homes built in San Jose before the late 1970s often have asbestos in drywall compound, flooring adhesive, or ceiling texture. Starting demolition without testing can force a work stoppage and abatement costs that nobody budgeted for. We test first.
- Lot coverage limits in Willow Glen. Willow Glen is full of deep lots, but the city limits how much of the lot can be covered by structures. Many San Jose homeowners discover they can’t add a ground-level ADU, so we build over existing detached garages instead, which counts differently under the coverage rules.
Pricing for ADU Builders in San Jose, CA
San Jose ADU construction runs from about $110,000 for a simple interior JADU to $420,000 for a larger custom detached unit. Detached ADUs generally land between $180,000 and $420,000; prefab installations with Abodu, Cover, or Dvele typically range from $220,000 to $320,000. JADUs and garage conversions run $110,000 to $190,000. What moves the number: foundation depth and seismic shear wall requirements, electrical panel capacity, sewer line condition, and whether the ADU needs a new service drop from the street. Every estimate includes a written line-item breakdown, and surprises are priced and approved in writing before we proceed. Call (669) 266-4319 to schedule a free estimate. No price changes at the door. Ever.
We Also Serve Cities Near San Jose
Lodgewick ADU San Jose serves homeowners across San Jose, plus Milpitas, Santa Clara, Los Gatos, and Los Altos. If you live in one of those nearby cities and are planning an ADU, the same written-price guarantee and 365-Day Done Right Promise apply. A live person answers our calls 24/7, whether you’re in Almaden Valley or downtown Milpitas. Dispatch and scheduling are coordinated from our San Francisco Bay Area office, and crews serve San Jose locally.
Serving San Jose, CA - Our Local Coverage Area
We’re based in the San Jose 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 San Jose
San Jose’s pre-approved ADU plans can cut permit review from several months to as little as 30 days, because the city has already vetted the design. However, those plans still require a soils report and shear wall upgrades due to the city’s proximity to the Hayward and Calaveras faults. We handle the soils report, the structural calcs, and the sher wall design so the pre-approved plan actually gets approved on schedule. Call (669) 266-4319 if you want a realistic timeline for your specific lot.
In a 1960s San Jose home, the three most common surprises are outdated electrical panels (often 100-amp), shallow sewer laterals that need upsizing to meet current code, and asbestos in original drywall or flooring. We test for asbestos before demolition and write allowances for panel upgrades and sewer work into the contract before we start. You’ll never get a surprise invoice from us. Call (669) 266-4319 for a JADU estimate with every allowance spelled out.
Yes, and many Willow Glen homeowners choose this route because lot coverage limits make ground-level ADUs impossible on some properties. The condition of the existing garage framing and foundation determines whether it’s feasible, so we inspect those structures carefully before designing. During a garage conversion in Willow Glen, our crew opened a 1963 structure to find the original sewer lateral only 14 inches below grade – too shallow for the new bathroom group. We wrote a change order for trenching and upsizing to a 4-inch ABS line before touching anything else, and the homeowner approved it the same day via our online portal. Call (669) 266-4319 to have us look at your garage.
Every ADU foundation we build in San Jose is engineered to the current California Building Code for the Hayward and Calaveras fault zones. That means deeper footings, specific shear wall details, and hold-down hardware that out-of-state plans often don’t include. The pre-approved ADU plans from the city still need this seismic engineering, so we don’t skip it – and we don’t charge you for a redesign later because an out-of-state detail got rejected at plan check. Call (669) 266-4319 for details on how we handle seismic on your lot.
Often yes. In older San Jose neighborhoods like Willow Glen, Rose Garden, and Cambrian, the original sewer laterals were buried shallower than current code allows, and they’re typically 3-inch clay pipe that can’t handle the additional flow from a new bathroom group. Connecting an ADU or JADU to a shallow, undersized lateral will fail inspection. We include sewer lateral assessment in every estimate, and if upsizing is required, it’s a written line item you approve before we dig. Call (669) 266-4319 for an estimate that covers your sewer line.
Get Your San Jose ADU Estimate in Writing
If you’re ready to know what an ADU or JADU will actually cost on your San Jose lot, call (669) 266-4319. Russ Delmar and the Lodgewick ADU San Jose team will inspect your property, walk the setbacks, check your panel, and give you a written price before any work begins. The 365-Day Done Right Promise is in the contract. If it’s not done right, we make it right. Call (669) 266-4319 today for your free estimate.
Written by Russ Delmar, Owner at Lodgewick ADU San Jose, serving San Jose and the surrounding Bay Area since 2010.
