Unlock New Space with Expert ADU Construction
Homeowners across San Jose, CA are discovering that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction creates a flexible new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has guided hundreds of local homeowners turn these plans to life with craftsmanship and integrity.
The demand for ADU construction has grown rapidly in recent years, and it's no mystery. California state law now makes it easier for homeowners to add these secondary units, and local municipalities like San Jose have embraced 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 provides increased control over how your property functions.
At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction job. Our team is familiar with city and county requirements, the engineering details, and the planning steps that make an ADU beautiful. When you're ready to explore what ADU construction could look like on your property, this guide covers everything you need to know.
What Is the ADU Construction Process?
ADU construction describes the process of designing, click here permitting, and building an accessory dwelling unit on a residential property. An accessory dwelling unit is a self-contained living space — including a kitchen, bathroom, sleeping area, and its own entrance — that exists on the same lot as a primary residence. ADU construction includes various structural types, including detached backyard units, attached additions, garage conversions, and even below-grade dwelling units.
Mechanically, everything kicks off with a detailed site assessment, where our team evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, design plans are prepared and submitted to the relevant municipal authority. Once approvals are in place, ADU construction transitions to the physical build phase — which covers everything from foundational work, framing, HVAC, drywall, flooring, and exterior finishes. The result is a move-in-ready 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 sized for independent daily use. Brother & Brother Builders handles every ADU construction job with the same high standards we apply to large-scale custom home projects.
Key Advantages ADU Construction
- Boosted Home Equity — ADU construction delivers real market value to your property, often returning more than the build cost when it's time to sell.
- Revenue Generation — A completed ADU can be rented as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
- Multi-Generational Living — ADU construction offers family members a comfortable home of their own without leaving the property.
- Design Flexibility — From two-bedroom configurations, ADU construction is adaptable to your household's priorities.
- Faster Permitting in California — Recent state legislation has minimized the barriers and delays associated with ADU construction, resulting in a timeline that is faster and less expensive 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 produces a fully self-contained unit where tenants live autonomously.
- Durable Return on Investment — A well-built ADU holds its value for the long haul by offering both functional space and financial upside.
The ADU Construction Journey Step by Step
- Site Evaluation and Zoning Analysis — Our builders assess your property to determine what type of ADU is allowed and where it can be placed. This stage clarifies exactly what ADU types will work before any money is spent on design.
- Blueprint Development and Layout Design — Experienced draftspeople create detailed floor plans based on your goals. Space is thoughtfully allocated to create practical, comfortable living.
- Permitting and City Approval — ADU construction in San Jose demands documentation to the city's building department for inspection and clearance. Our team handles all submissions on your behalf, responding to review feedback promptly.
- Excavation and Foundation Installation — Once permits are issued, physical construction begins. This involves leveling and prepping the ground, completing foundation work, and running initial plumbing and electrical conduits.
- Shell Construction and Exterior Finishing — The structural frame is erected followed by roofing, siding, windows, and exterior doors. At this stage, the ADU takes its visible shape.
- Interior Systems and Infrastructure — Skilled tradespeople install the heating, cooling, drainage, and power infrastructure that make the ADU ready for occupancy. All work is inspected at each code checkpoint throughout ADU construction.
- Interior Finishing and Final Inspections — Trim, appliances, tile, and lighting are placed and inspected to the approved plan. A last official inspection issues the certificate of occupancy and the ADU is ready for use.
Who Is a Right Fit for ADU Construction?
Property owners who are best suited from ADU construction generally fit within a few common profiles. If you are a homeowner with enough lot space to meet setback requirements, you're already a strong candidate. Homeowners wanting to add a revenue stream through rental are among the most motivated ADU construction clients, along with families accommodating adult children who need housing.
Another strong candidate is someone who needs a dedicated professional workspace and wants a private work environment that doesn't interfere with your family's daily life. Landlords and real estate investors who are building a portfolio are also well suited for ADU construction, since rental income frequently offsets build costs.
Situations where ADU construction may not be the best first step include sites with unusual utility access challenges. Very small lots or properties with easements may need a modified approach. Brother & Brother Builders reviews each property case by case to advise you on what's feasible.
ADU Construction Frequently Asked Questions
How long does ADU construction usually take from start to finish?
The total process for ADU construction typically ranges from six to fourteen months, influenced by the type of unit being built and city review schedules. The approval phase alone can take a significant portion of the overall timeline in San Jose, so beginning the process sooner rather than later is wise. Straightforward interior conversions can move faster, while multi-room detached cottages require more time.
What does ADU construction typically cost?
Pricing depends on many factors based on whether it's a conversion or new construction. Locally, ADU construction generally falls between $150,000 to $400,000 or more for a detached new build. Garage conversions are generally priced lower, sometimes starting around $80,000 depending on scope. A detailed estimate can only be produced following a thorough property review.
Is ADU construction difficult to live through while it's underway?
The day-to-day impact depends on whether you're converting existing space or building new. 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 specific stages like framing or MEP rough-in. Our team communicates clearly about upcoming work and timelines.
Do I need to leave my home during ADU construction?
In most cases, you do not need to vacate your main home during ADU construction. Most job sites are designed so that you stay in your primary unit throughout the build. Certain situations could require a brief departure if interior conversion work touches shared systems in ways that require short-term access disruption. The team at Brother & Brother Builders will discuss these scenarios during the kickoff meeting.
How long will an ADU built through professional ADU construction remain in good condition?
An ADU constructed with quality materials should last as long as your primary home — indefinitely with proper upkeep. Durability depends to the quality of materials used, whether the unit is properly cared for, and if mechanical components are maintained on schedule. Brother & Brother Builders specifies commercial-grade materials and comply with all local building codes to ensure lasting performance.
ADU Construction for Local Homeowners
Residential areas across San Jose present a variety of property types that are well suited for ADU construction. Residents in the Rose Garden district often discover their properties accommodate detached backyard units nicely. Communities around the Capitol Expressway corridor are seeing more homeowners add secondary units as families expand. If you're located closer to Evergreen, our team knows the permitting landscape well.
San Jose's permitting office applies particular standards for ADU construction that experienced builders know well. Location near major arterials like Story Road or Tully Road can affect how quickly permits are approved for a given ADU project. Our familiarity with this region's building landscape means more accurate timelines and budgets from kickoff through certificate of occupancy.
Start Your ADU Construction Assessment Today
When you want to move forward with ADU construction, Brother & Brother Builders is the team to call. Our builders provide proven skills in ADU construction across a wide range of project types — from simple garage conversions to multi-room backyard residences. The process begins with a detailed, no-pressure consultation where we understand your vision and provide an honest assessment of what the project will involve.
Contact Brother & Brother Builders to set up your consultation. No matter where you are in the decision-making process, our team is happy to answer questions, share examples of our work and help you take the next step. ADU construction is a significant investment — 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