A free site visit, a check of what your lot allows and a written, line-item price.
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Adding an accessory dwelling unit (ADU), a small independent home built on the same lot as your main house, is the fastest way for San Jose homeowners to gain rental income, a private space for aging parents, or room for adult kids who can’t afford Bay Area rent. It’s also a project where price surprises and contractor no-shows are common enough that many homeowners put it off for years. Lodgewick ADU San Jose, led by Russ Delmar under the Kingswell family of home-service companies, has built a reputation since 2010 on a single promise: a written price before any work starts, a real arrival window, a clean job site, and a written 365-Day Done Right Promise on every project. If you’re weighing an ADU in San Jose, call (669) 266-4319 and we’ll walk you through the numbers honestly, or learn more about our San Jose ADU Builders process first.
ADU Construction
ADU Construction is the full process of building an accessory dwelling unit from foundation to finish work, including site prep, framing, plumbing, electrical, drywall, roofing, and final inspection. In San Jose, full construction on a standard one-bedroom ADU typically lands between $250,000 and $400,000 depending on site conditions, utility tie-ins, and finish level. Lodgewick ADU San Jose manages every phase with a written scope and price, so you know what’s happening before the crew shows up and what it will cost when they leave.
Site Prep and Foundations
San Jose lots vary widely, from flat Willow Glen parcels to hillside lots in the East Foothills that need more excavation and retaining work. We handle grading, drainage, and foundation systems matched to your soil conditions. The written price covers what we find during site prep and we flag anything unexpected before it becomes a change order.
Framing Through Finish
Once the foundation is set, framing moves quickly and the building starts to look like a real home. Our background-checked, uniformed crews handle framing, roofing, windows, and exterior siding with brands like James Hardie where the design calls for it. Each day ends with a clean job site, per The Kingswell Way.
Detached ADU
A Detached ADU is a standalone structure built separately from your main house, usually in the rear yard or side yard, with its own address, entrance, and utility meters. Detached ADUs in San Jose generally run $280,000 to $450,000, though larger two-bedroom units or units on difficult lots can exceed that range. Lodgewick ADU San Jose has built detached units across San Jose, from small 400-square-foot studios behind bungalows in Alum Rock to two-bedroom family units in spacious ADU Builders in Los Gatos lots.
When a Detached ADU Makes Sense
If you have a usable backyard and want maximum privacy for tenants or family, a detached ADU is usually the best choice. You avoid shared walls, which means less noise transfer and fewer disputes. Rent potential is also typically higher for a detached unit because it feels like a real standalone home, not a converted garage.
Utility Connections and Permitting
Detached ADUs in San Jose require separate utility connections for water, sewer, and power, which can add cost if your main panel is far from the build site. We pull all permits and coordinate with San Jose’s building department from the first plan check through final inspection. The written price includes permit fees, so that line item doesn’t surprise you later.
JADU
A JADU, or junior accessory dwelling unit, is a smaller living unit created within the walls of your existing home, typically by converting a bedroom, garage area, or bonus room into a compact studio with its own entrance and small kitchen. JADUs in San Jose cost significantly less than detached ADUs, usually between $80,000 and $180,000 depending on whether you’re converting existing space or adding a small bump-out. Lodgewick ADU San Jose handles JADU conversions throughout San Jose, and these projects are often the quickest path to a rentable unit because they reuse existing structure and utilities.
Size Limits and Owner Occupancy
San Jose caps JADUs at 500 square feet, and state law requires the property owner to live in either the main house or the JADU. That rule works well for homeowners who want rental income without leaving their property. We handle the plans and paperwork so your JADU meets every San Jose requirement before framing starts.
Converting a Garage or Bedroom
The most common JADU projects we build in San Jose are garage conversions and bedroom conversions with a private entrance added. The cost difference between a garage conversion and adding new square footage is substantial. We give you a written price for each option so you can decide with real numbers, not guesses.
ADU Plans
ADU Plans are the architectural drawings, structural calculations, and permit documents required before any ADU construction can legally begin in San Jose. A complete plan set for a San Jose ADU typically costs $8,000 to $25,000 depending on the unit’s complexity, whether it’s a standard plan from a prefab brand like Abodu or a custom design, and how many revision rounds the city requires. For comparison, ADU Builders - Santa Clara often faces different review timelines. Lodgewick ADU San Jose handles plan development from concept to stamped approval, working with designers familiar with San Jose’s specific ADU ordinance, which differs from neighboring cities like Fremont and Palo Alto.
Standard Plans vs. Custom Design
If you’re building with a factory-built system from Plant Prefab or Abodu, the manufacturer’s standard plans can often be adapted to your San Jose lot at lower cost than a fully custom set. Custom designs give you more room to work with odd lot shapes, hillside setbacks, or specific aesthetic goals. We price both options in writing so you can choose based on real costs.
Plan Review and Resubmission
San Jose’s building department can be thorough, and plan-review comments are a normal part of the process. We respond to every comment, resubmit drawings, and track the approval timeline so your project doesn’t stall. The goal is a stamped, approved plan set that lets construction start without surprises.
ADU Contractor
An ADU Contractor is a licensed general contractor who coordinates the entire ADU build, including subcontractors for plumbing, electrical, HVAC, and roofing, and who is accountable for the finished product. Working with a contractor who specializes in ADUs rather than a general home remodeler matters because ADUs have unique code requirements and cost drivers. Lodgewick ADU San Jose operates 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.
Subcontractor Management
Every subcontractor we bring to your San Jose ADU project is background-checked and shows up in uniform, so you always know who’s on your property. We schedule, coordinate, and inspect their work before it’s covered up. If a sub’s work doesn’t meet our standard, it gets fixed before we move on.
Change Orders and Price Protection
The most common complaint we hear from San Jose homeowners who’ve had a bad contractor experience is a price that changed once the project was underway. Our written price protects you from that. If site conditions genuinely require additional work, we show you what changed and put the new price in writing before we do the work. No door-knock surprise pricing. Ever.
ADU Design
ADU Design is the process of planning your ADU’s layout, appearance, and functionality before construction begins, including floor plan, exterior style, window placement, and material choices. Design affects everything from construction cost to rent potential. In San Jose, a well-designed ADU can rent for $2,200 to $3,200 per month depending on neighborhood, while a poorly laid-out unit may sit empty. Lodgewick ADU San Jose works with materials and systems from suppliers like James Hardie and Tuff Shed to match your ADU’s exterior to your main house and your San Jose neighborhood’s character.
Layout and Rentability
The biggest design mistake we see is a floor plan that wastes square footage on a big living room while the kitchen feels like an afterthought. San Jose renters look at kitchen function, storage, and natural light first. We design around those priorities so your unit rents quickly and for a rate that justifies the build cost.
Matching Your Existing Home
San Jose has strict design guidelines for ADUs, especially in older neighborhoods where a modern box would look out of place. We work with materials and rooflines that complement your existing home, which also helps with resale value. Whether you want a unit that matches your Craftsman in Alum Rock or a modern prefab in East Foothills, the design gets settled before pricing is locked.
Backyard ADU
A Backyard ADU is a detached accessory dwelling unit placed in the rear yard of your San Jose property, positioned to preserve outdoor living space while maximizing privacy and natural light for both the main house and the new unit. Backyard ADUs in San Jose typically run $280,000 to $450,000 depending on size, site access, and finish level. Lodgewick ADU San Jose specializes in backyard units, and the name fits the work: a lodge is a small house on a larger property, which is exactly what a backyard ADU is.
Placement and Setbacks
San Jose requires specific setbacks from property lines, and the placement of your ADU affects solar access, privacy, and how much yard remains usable. We evaluate your lot before design starts so the unit sits where it makes sense, not just where it’s easy to build. A well-placed backyard ADU feels intentional, not squeezed in.
Site Access for Construction
If your San Jose lot has narrow side yards or limited street access, the construction sequence has to be planned carefully. For some tight lots, prefab options from manufacturers like Abodu or Boxabl reduce on-site construction time significantly. We’ll tell you honestly whether a factory-built unit or stick-built approach fits your site and budget better.
Brands We Service
We build with a range of established ADU manufacturers and materials suppliers, chosen per project based on your lot, budget, and timeline. Abodu produces factory-built detached units that can go from permit to move-in in as little as six months, and we’ve completed Abodu installations across San Jose where the shorter timeline mattered more than full design flexibility. Plant Prefab offers higher-end custom panelized construction, which works well on San Jose hillside lots where traditional site framing gets complicated.
For materials, we specify James Hardie fiber cement siding on a large share of our San Jose ADUs because it holds up to California’s dry summers and rainy winters better than wood, and fire-resistant siding is a real consideration in the East Foothills. Tuff Shed structures sometimes serve as the starting point for a garage conversion or workshop-to-ADU transformation. Whether you have a specific brand in mind or want us to recommend what fits, we can help.
Signs You Need a Pro Right Now
- Your contractor has gone quiet mid-project. If framing is done but nobody’s returned your calls in three weeks, a half-built ADU in San Jose is exposed to weather and theft. We’ve taken over more than a few abandoned projects and can assess what’s salvageable.
- The price changed after the work started. A contractor who tacks on “unforeseen” costs after demolition is a red flag you shouldn’t ignore. Our written price protects you from exactly this, and we document any legitimate change before work continues.
- Your plans were rejected by the city. San Jose’s building department sends back flawed plan sets all the time. If you’ve had a rejection and don’t know how to respond, bring us the comments. We’ll get the plans corrected and back in review.
- You’re not sure if your garage can legally become an ADU. San Jose has specific rules about garage conversions, parking replacement, and ceiling height. We’ll tell you what’s legal and what it costs before you spend money on plans.
- You have a family member who needs housing soon. If an aging parent or adult child needs a place in the next 12 months, the timeline matters more than usual. We’ll give you a realistic schedule for a San Jose ADU based on current city permit backlog.
Our Process, Step by Step
- 1
Site visit and feasibility check. Russ Delmar or a senior project lead walks your San Jose property with you, measuring the lot, checking utility access, and identifying any constraints like protected trees or steep slopes. You get an honest read on what’s possible before any money changes hands.
- 2
Written scope and price. Based on the site visit and your goals, we produce a written price that covers the scope we discussed. This is a real number, not a ballpark, and it’s what you’ll pay unless you ask for changes.
- 3
Plans and permits. We coordinate with the designer, engineer, and San Jose’s building department to get a stamped, approved plan set. You’re kept informed at each step, and we handle every resubmission.
- 4
Construction with defined arrival windows. Our background-checked crews show up in the window we gave you, work through the build sequence, and leave a clean job site at the end of each day. The Kingswell Way is the standard, not the exception.
- 5
Final walkthrough and written guarantee. Before you sign off, we walk the finished unit together and fix anything that’s not right. Then you receive the written 365-Day Done Right Promise: if something fails within the guarantee period, we come back and make it right at no charge.
How Much Does ADU Builders Cost in San Jose?
A typical one-bedroom detached ADU in San Jose runs between $280,000 and $400,000 all-in, including plans, permits, utility connections, and construction. Garage conversions into ADUs usually land between $120,000 and $200,000 because the structure already exists. JADUs, which stay within your home’s existing footprint, start around $80,000 and top out near $180,000. Two-bedroom detached units or units on hillside lots in the East Foothills can push past $450,000 based on foundation work and site access.
What drives the price: lot conditions, whether utilities need upgrading, finish level (a rental-ready finish costs less than a luxury guest suite), and whether you choose site-built or prefab like Abodu. To keep costs down without cutting corners, decide on finishes before construction starts, avoid changing the plan mid-build, and choose a contractor who gives a written price so you’re not funding their estimating errors. Our free estimate includes a line-item breakdown so you can see exactly where your money goes before you commit to anything. Call (669) 266-4319 to schedule yours.
Our Service Area Near San Jose
Lodgewick ADU San Jose builds ADUs throughout San Jose and the surrounding communities, including ADU Builders in Fremont, Milpitas, Union City, Los Gatos, Los Altos, and the East Foothills. We also serve homeowners up the Peninsula, where our team shares standards and processes with ADU Builders in Palo Alto. If you’re in Burbank, Alum Rock, or Portola Valley, ADU Builders in San Jose covers your project too. Response times for site visits are typically within a few business days depending on your neighborhood.
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.
Frequently Asked Questions About ADU Builders in San Jose
ADU Builders refers to contractors who specialize in building accessory dwelling units, which are small independent homes on the same property as a main house. Unlike general remodelers, ADU Builders - Milpitas and San Jose ADU builders focus on the specific code, permitting, and design requirements that ADUs in San Jose must meet. Lodgewick ADU San Jose has specialized in ADUs since 2010 under the Kingswell family of home-service companies.
A site-built detached ADU in San Jose typically takes 9 to 14 months from design start to final inspection, with prefab units from Abodu often completing in 6 to 9 months. San Jose’s plan-review timeline is a major variable and can add 2 to 4 months depending on current backlog. We give you a written schedule at the start and update it as your project moves through permitting.
Most San Jose ADUs cost between $80,000 for a simple JADU and $450,000 for a larger two-bedroom detached unit, with the typical one-bedroom detached ADU landing around $280,000 to $400,000. Your lot, finish choices, and utility requirements determine where you fall in that range. Call (669) 266-4319 for a free estimate with a line-item breakdown.
Yes, we install and finish units from Abodu, Plant Prefab, and other factory-built ADU manufacturers. Prefab can shorten your construction timeline and reduce weather exposure during framing. We’ll tell you honestly whether a prefab or site-built approach fits your San Jose lot and budget better.
If you have a half-finished ADU or a contractor who disappeared mid-project, call (669) 266-4319. We assess abandoned projects, identify what’s code-compliant and what needs to be redone, and give you a written price to finish the work. A live person answers our phones 24/7, including weekends.
The 365-Day Done Right Promise is a written guarantee delivered on every ADU project. If anything we built fails within 365 days of completion, we come back and fix it at no charge, including a free return visit. The promise is in writing before construction starts, so you’re not relying on a verbal handshake.
Gather any existing property surveys, past permit documents, and a rough idea of what you want the ADU to be used for, since that shapes size and finish choices. Clear access to the portion of the yard where you’re considering the unit helps us measure accurately. Don’t worry about having the perfect vision; we’ll walk through options during the visit and give you real pricing for each.
Schedule Your ADU Builders Service in San Jose Today
Ready to get a real number for your San Jose ADU? Call (669) 266-4319 to schedule a free, no-obligation estimate. We’ll walk your property, talk through what’s possible, and put the price in writing before you commit to anything. A live person answers, around the clock, every day of the week.
Written by Russ Delmar, Owner at Lodgewick ADU San Jose, serving San Jose since 2010.
