Expand Your Home with Quality ADU Construction
Property owners throughout San Jose, CA are finding that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction creates a flexible new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has helped hundreds of local homeowners bring these projects to life with skill and care.
The demand for ADU construction has increased significantly in recent years, and it's easy to understand why. California state law now makes it easier 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 apply deep hands-on experience to every ADU construction project. Our team knows the San Jose building codes, the engineering considerations, and the aesthetic decisions that make an ADU beautiful. Should you want to learn about what ADU construction could look like on your property, this guide explains everything you need to know.
What Is ADU Construction?
ADU construction involves the process of planning, approving, and constructing an accessory dwelling unit on a residential property. An accessory dwelling unit is a fully independent living space — including 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 basement or interior conversions.
Mechanically, everything kicks off with a thorough property evaluation, where our team evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, architectural drawings are prepared and submitted to the relevant municipal authority. Once the paperwork is cleared, 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 fully functional living unit attached to or separate from your main home.
What sets quality ADU construction apart is the attention to detail at every stage. Components should be specified to complement the existing structure. Systems like plumbing and electrical must be sized for independent daily use. Brother & Brother Builders treats each project with the same professional rigor we apply to large-scale custom home projects.
Key Reasons to Choose ADU Construction
- Higher Resale Potential — 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 can be rented 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 private, independent living space without losing proximity to the family.
- Design Flexibility — From open-plan one-bedrooms, ADU construction may be customized to the intended occupant's lifestyle.
- Faster Permitting in California — Recent state legislation has minimized the red tape associated with ADU construction, creating a path that is faster and more cost-efficient than ever before.
- Sustainable Land Use — Building an ADU maximizes the land you already own instead of expanding urban sprawl, which contributes to sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where occupants have full privacy.
- Lasting Financial Benefit — A well-built ADU remains an asset for many years and generates both livable square footage and monetary benefit.
The ADU Construction Process Step by Step
- Property Walkthrough and Feasibility Check — Our experts review your property to evaluate setbacks, lot coverage limits, and utility connections. This stage clarifies exactly what can be built before any money is spent on design.
- Blueprint Development and Layout Design — Experienced draftspeople create detailed floor plans reflecting your priorities. 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 sign-off and verification. We manage this entire process on your behalf, addressing any city comments promptly.
- Site Preparation and Foundation Work — Once permits are issued, physical construction begins. This involves leveling and prepping the ground, pouring the concrete foundation, and running initial plumbing and electrical conduits.
- Framing, Roofing, and Exterior Work — Framing is completed followed by weatherproofing and exterior finish materials. At this stage, the ADU transforms from a concept to a building.
- Mechanical, Electrical, and Plumbing Installation — Certified technicians install the plumbing lines, electrical wiring, and HVAC systems that make the ADU ready for occupancy. Inspections are completed at required milestones throughout ADU construction.
- Interior Finishing and Final Inspections — Countertops, hardware, finishes, and fixtures are installed and finished to your specifications. A final city inspection grants legal occupancy status and the unit is officially approved for use.
Who Is a Strong Candidate for ADU Construction?
People who see the greatest return from ADU construction generally fit within a few recognizable groups. If you have a residential property with available square footage under zoning rules, you're already in a good starting place. Homeowners wanting to add a revenue stream through rental are among the most common ADU construction clients, along with families accommodating adult children who need housing.
ADU construction also suits someone who works from home and wants a separate office or studio space that is distinct from your family's daily life. Landlords and real estate investors who already own residential properties are also well suited for ADU construction, since the return on investment is well-documented.
Situations where ADU construction may not be the best first step include lots that are below minimum size thresholds. Very small lots or properties with easements may require additional review. Our team can assess each property on its own merits to provide realistic options.
ADU Construction FAQ
How long does ADU construction typically 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 how quickly approvals come through. Permitting alone can take two to four months in San Jose, so planning ahead matters. Straightforward interior conversions may complete more quickly, while multi-room detached cottages fall toward the upper end of the timeline.
What does ADU construction usually run in terms of budget?
Budget requirements differ based on whether it's a conversion or new construction. In the San Jose area, ADU construction generally falls between $150,000 to $400,000 or more for a detached new build. Interior conversion projects tend to cost less, sometimes starting around $80,000 depending on scope. An accurate budget can only be given after completing a formal feasibility evaluation.
Is ADU construction intrusive while it's underway?
The day-to-day impact depends on whether you're converting existing space or building new. Standalone ADU projects are usually easier to live alongside, since work happens away from the main house. Projects that connect to the main structure may involve some shared wall work during certain phases of construction. Brother & Brother Builders keeps you informed about any phases that may affect your routine.
Do I need to vacate the property during ADU construction?
Generally speaking, you do not need to vacate your main home during ADU construction. Most builds are set up to let you remain on the property throughout the build. Exceptions may arise if interior conversion work touches shared systems in ways that briefly affect habitability. Our project managers will flag these situations during the pre-construction consultation.
How long will an ADU built through professional ADU construction remain in good condition?
A well-built ADU is designed to last as long as any standard residential structure — typically 50 years or more. Longevity is tied to the quality of materials used, how consistently minor repairs are addressed, and if mechanical components are maintained on schedule. Brother & Brother Builders specifies residential-grade products rated for longevity and build to current California residential standards to ensure lasting performance.
ADU Construction for Local Homeowners
San Jose's neighborhoods offer a wide range of property types that are well suited for ADU construction. Residents in the check here Rose Garden district often discover their properties are well configured for ADU builds. Neighborhoods near Blossom Hill Road are seeing more homeowners add secondary units as multigenerational living becomes more common. Whether your property is near downtown San Jose, our team has project experience in the area.
The City of San Jose's building department follows defined procedures for ADU construction that require a builder familiar with local expectations. Location near major arterials like Story Road or Tully Road can influence utility connection requirements for a given ADU project. Brother & Brother Builders' experience across the San Jose permitting environment means smoother project delivery from the first meeting to the final inspection.
Book Your ADU Construction Consultation Today
If you're ready to add an ADU to your property, Brother & Brother Builders is the team to call. We bring proven skills in ADU construction across a wide range of project types — from small attached additions to multi-room backyard residences. Every project starts with a thorough and honest property review where we understand your vision and share clear expectations of what the project will involve.
Reach out to our team to schedule a site visit. Whether you're in the early stages of planning, we enjoy discuss timelines, costs, and design possibilities and help you take the next step. 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