Unlock New Space with Quality ADU Construction
Property owners throughout San Jose, CA are realizing that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction opens the door to a flexible new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has helped hundreds of local homeowners see these visions to life with precision and integrity.
The demand for ADU construction has grown rapidly in recent years, and it's no mystery. California state law has streamlined permitting 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 provides increased control over how your property serves your household.
At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction build. Our team knows the San Jose building codes, the engineering details, and the planning steps that make an ADU beautiful. If you've been thinking about what ADU construction could do for your property, this guide covers everything you need to know.
What Is an ADU Build?
ADU construction describes the process of planning, approving, and constructing an accessory dwelling unit on a residential property. An accessory dwelling unit is a complete living space — featuring a kitchen, bathroom, sleeping area, and its own entryway — that sits on the same property as a primary residence. ADU construction comes in multiple configurations, including detached backyard units, attached additions, garage conversions, and even below-grade dwelling units.
Mechanically, the process begins with a thorough property evaluation, where our builders evaluate property boundaries, available square footage, and infrastructure capacity. From there, blueprints are prepared and submitted to the relevant municipal authority. Once permits are secured, ADU construction enters the physical build phase — which encompasses site preparation, framing, roofing, plumbing, electrical, insulation. The result is a fully functional living unit connected to or independent of your main home.
What separates excellent ADU construction from an average project is the attention to detail at every stage. Products need to be chosen to match the primary home's aesthetic. Systems like wiring and water supply must be designed to handle full-time occupancy. Brother & Brother Builders approaches every build with the same professional rigor we apply to large-scale custom home projects.
Key Reasons to Choose ADU Construction
- Increased Property Value — 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.
- Housing for Extended Family — ADU construction offers family members a private, independent living space without leaving the property.
- Design Flexibility — From two-bedroom configurations, ADU construction may be customized to your household's priorities.
- Faster Permitting in California — Recent state legislation has minimized the permitting obstacles associated with ADU construction, creating a path that is faster and less expensive than ever before.
- Sustainable Land Use — Building an ADU uses your existing lot instead of requiring new development, which contributes to sustainability goals.
- Separate Entrances and Spaces — 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 holds its value for many years and generates both usable housing and equity growth.
The ADU Construction Process Step by Step
- Site Evaluation and Zoning Analysis — Our experts review your property to evaluate setbacks, lot coverage limits, and utility connections. This stage clarifies exactly what's possible before any resources go toward planning.
- Custom Design and Architectural Planning — Experienced draftspeople create detailed floor plans based on your goals. Every square foot is planned 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. Brother & Brother Builders coordinates the permitting on your behalf, addressing any city comments promptly.
- Site Preparation and Foundation Work — Once permits are issued, the build starts. This covers land preparation, laying the structural base, and running initial plumbing and electrical conduits.
- Framing, Roofing, and Exterior Work — Walls and roof systems go up followed by insulation, sheathing, and exterior cladding. During this step, the ADU transforms from a concept to a building.
- Mechanical, Electrical, and Plumbing Installation — Skilled tradespeople install the heating, cooling, drainage, and power infrastructure that make the ADU fully functional. Inspections are completed at each code checkpoint throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are installed and finished to your specifications. A closing municipal review grants legal occupancy status and your new space is cleared for use.
Who Is a Right Fit for ADU Construction?
People who see the greatest return from ADU construction generally fit within a few clear categories. If you own a single-family home with a backyard, garage, or basement that could be converted, you're already well-positioned. Homeowners hoping to offset mortgage costs through rental are among the most common ADU construction clients, along with families accommodating adult children who need housing.
You may also be someone who works from home and wants a private work environment that remains away from your family's daily life. Real estate-minded homeowners who already own residential properties 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 face additional constraints. Our team can assess each property individually and honestly to recommend the right path forward.
ADU Construction Common Questions Answered
How long does ADU construction usually take from start to finish?
The complete duration for ADU construction typically ranges from six to fourteen months, based on the project scope and city review schedules. Permitting alone can take several months in San Jose, so planning ahead matters. Straightforward interior conversions can move faster, while custom detached builds fall toward the upper end of the timeline.
What does ADU construction usually run in terms of budget?
Costs vary widely based on project complexity and finishes selected. In the San Jose area, ADU construction generally falls between $150,000 to $400,000 or more for a standalone backyard unit. Attached ADU additions tend to cost less, sometimes in the $80,000 to $150,000 range. An accurate budget can only be developed after a full site assessment.
Is ADU construction difficult to live through while it's underway?
The level of disruption 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 create short-term inconveniences during certain phases of construction. Brother & Brother Builders keeps you informed about any phases that may affect your routine.
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. The vast majority of projects are designed so that you continue living in the home throughout the process. Certain situations could require a brief departure 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 hold up?
A well-built ADU should last as long as the main residence — often several decades with routine maintenance. Durability depends to the standard of construction, how well routine maintenance is performed, and how proactively issues are resolved over time. Brother & Brother Builders specifies residential-grade products rated for longevity and follow all code requirements to protect your investment for the long haul.
ADU Construction for Local Homeowners
Residential areas across San Jose present a variety of property types that are well suited for ADU construction. Homeowners in the Willow Glen neighborhood have found their lots work well for both attached and detached projects. Communities around the Capitol Expressway corridor are seeing more homeowners add secondary units as housing demand rises. If you're located closer to Evergreen, our team knows the permitting landscape well.
The City of San Jose's building department follows defined procedures 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. Brother & Brother Builders' experience across this region's building landscape means more accurate timelines and budgets from design through the final walkthrough.
Schedule Your ADU Construction Consultation Today
If you're ready to move forward with ADU construction, Brother & Brother Builders is here to help. Our builders provide proven skills in ADU construction for many different project types — from modest studio builds to large custom detached cottages. The process begins with a comprehensive site assessment where we understand your vision and provide an honest assessment of what's achievable.
Reach website out to our team to schedule a site visit. Even if you're just exploring the idea, our team is happy to discuss timelines, costs, and design possibilities and give you the clarity you need to move forward. ADU construction is a significant investment — and we're committed to helping you get it right.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632