Unlock New Space with Expert ADU Construction
Property owners throughout San Jose, CA are discovering that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction provides a powerful new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has guided hundreds of local homeowners see these visions to life with precision and care.
The demand for ADU construction has surged in recent years, and it's not hard to see why. California state law has simplified the process for homeowners to add these secondary units, and local municipalities like San Jose have encouraged the trend as a way to increase density responsibly. Whether you want to build a detached backyard cottage, a garage conversion, or an attached addition, ADU construction gives you more control over how your property works.
At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction build. Our team is familiar with city and county requirements, the engineering considerations, and the aesthetic decisions that make an ADU beautiful. If you've been thinking about what ADU construction could do for your property, this guide will walk you through everything you need to know.
What Is an ADU Build?
ADU construction involves the process of designing, permitting, and building an accessory dwelling unit on a residential property. An accessory dwelling unit is a complete living space — equipped with a kitchen, bathroom, sleeping area, and its own entryway — that sits on the same property as a primary residence. ADU construction can take several forms, including detached backyard units, attached additions, garage conversions, and even interior space reconfigurations.
Mechanically, the work starts with a thorough property evaluation, where our builders evaluate property boundaries, available square footage, and infrastructure capacity. From there, architectural drawings are prepared and submitted to the local building department. Once the paperwork is cleared, ADU construction transitions to the physical build phase — which covers everything from foundational work, framing, roofing, plumbing, electrical, insulation. The result is a fully functional living unit adjacent to or detached from your main home.
The difference between a good and a great ADU build is the level of craftsmanship at every stage. Components should be specified to align with the neighborhood's character. Systems like plumbing and electrical must be built for long-term residential demand. Brother & Brother Builders approaches every build with the same technical discipline we bring to full custom home projects.
Key Reasons to Choose ADU Construction
- Boosted Home Equity — ADU construction contributes significant market value to your property, often increasing appraised value substantially when it's time to sell.
- Monthly Cash Flow — A completed ADU is leasable as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
- Multi-Generational Living — ADU construction offers family members a self-contained residence without leaving the property.
- Customization Options — From modern studio layouts, ADU construction may be customized to the intended occupant's lifestyle.
- Faster Permitting in California — Recent state legislation has cut down the permitting obstacles associated with ADU construction, resulting in a timeline that is faster and more affordable than ever before.
- Efficient Use of Your Lot — Building an ADU works within your current footprint instead of expanding urban sprawl, which contributes to sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where residents have their own space.
- Durable Return on Investment — A well-built ADU continues to produce returns for the long haul by offering both livable square footage and monetary benefit.
The ADU Construction Procedure Step by Step
- Property Walkthrough and Feasibility Check — Our experts review your property to evaluate setbacks, lot coverage limits, and utility connections. This phase answers exactly what ADU types will work before any money is spent on design.
- Blueprint Development and Layout Design — Experienced draftspeople create comprehensive blueprints tailored to your needs. Space is thoughtfully allocated to create practical, comfortable living.
- Permit Submission and Municipal Review — ADU construction in San Jose demands documentation to the city's building department for sign-off and verification. Our team handles all submissions on your behalf, responding to review feedback promptly.
- Ground Prep and Structural Base — Once permits are granted, the build starts. This includes grading the site, laying the structural base, and running initial plumbing and electrical conduits.
- Structural Framing and Weatherproofing — Framing is completed followed by insulation, sheathing, and exterior cladding. At this stage, the ADU transforms from a concept to a building.
- MEP Systems Rough-In — Skilled tradespeople install the heating, cooling, drainage, and power infrastructure that make the ADU fully functional. All work is inspected at required milestones throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are installed and finished to your specifications. A last official inspection confirms the unit is code-compliant and the unit is officially approved for use.
Who Is a Good Candidate for ADU Construction?
Homeowners who benefit most from ADU construction typically fall into a few common profiles. If you have a residential property with available square footage under zoning rules, you're already in a good starting place. Homeowners looking to generate income through rental are among the most motivated ADU construction clients, along with families navigating multigenerational living situations.
ADU construction also suits someone who runs a small business and wants a separate office or studio space that doesn't interfere with your family's daily life. Landlords and real estate investors who already own residential properties are also prime candidates for ADU construction, since the return on investment is well-documented.
Those who should discuss alternatives first include lots that are below minimum size thresholds. Sites with underground infrastructure conflicts may need a modified approach. Our team can assess each property on its own merits to recommend the right path forward.
ADU Construction Frequently Asked Questions
How long does ADU construction generally take from start to finish?
The total process for ADU construction usually runs between six to fourteen months, influenced by the type of unit being built and city review schedules. The approval phase alone can take two to four months in San Jose, so planning ahead matters. Smaller detached units can move faster, while larger new construction ADUs take longer to complete.
What does ADU construction cost in San Jose?
Pricing depends on many factors based on the type and size of the ADU. For most projects in this region, ADU construction generally falls between $150,000 to $400,000 or more for a detached new build. Attached ADU additions tend to cost less, sometimes in the $80,000 to $150,000 range. A detailed estimate can only be given after completing a thorough property review.
Is ADU construction disruptive while it's underway?
How much the build affects daily life depends on where the ADU is being built. New construction in the rear yard are generally the least intrusive, since the crew operates at a distance from your living areas. Interior conversions may involve some shared wall work during certain phases of construction. We provide advance notice about upcoming work and timelines.
Do I need to move out during ADU construction?
For the majority of homeowners, you do not need to vacate your main home during ADU construction. Most builds are structured to allow you remain on the property throughout the build. Exceptions may arise if major utility upgrades affect the main house in ways that require short-term access disruption. Our project managers will flag these situations during the kickoff meeting.
How long will an ADU built through professional ADU construction remain in good condition?
A well-built ADU should last as long as your primary here home — typically 50 years or more. How long it lasts comes down to the standard of construction, whether the unit is properly cared for, and whether systems like roofing and plumbing are serviced regularly. We select commercial-grade materials and follow all code requirements to ensure lasting performance.
ADU Construction for Local Homeowners
San Jose's neighborhoods offer a diverse mix of property types that are well suited for ADU construction. Property owners near the Almaden Valley area frequently see their parcels work well for both attached and detached projects. The Berryessa area have seen growing ADU activity as housing demand rises. Whether your property is near downtown San Jose, our team has likely worked nearby.
Local regulatory bodies in this area applies particular standards for ADU construction that experienced builders know well. Access to infrastructure along thoroughfares like Monterey Road can impact the design approach for a given ADU project. Brother & Brother Builders' experience across the San Jose permitting environment means more accurate timelines and budgets from kickoff through certificate of occupancy.
Book Your ADU Construction Assessment Today
If you're ready to explore what an ADU could look like on your lot, Brother & Brother Builders is ready to guide you. Our builders provide years of hands-on experience in ADU construction including all types of project types — from small attached additions to fully independent secondary homes. Our approach opens with a thorough and honest property review where we learn what you're trying to accomplish and share clear expectations of what the project will involve.
Contact Brother & Brother Builders to set up your consultation. Whether you're in the early stages of planning, our team is happy to discuss timelines, costs, and design possibilities and make sure you feel confident before committing. Building an ADU is a major decision — and we want to make sure it's the right one for you.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632