Transform Your Property with Quality ADU Construction

Property owners throughout San Jose, CA are finding that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction provides a flexible new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has supported hundreds of local homeowners bring these projects to life with craftsmanship and integrity.

The popularity of ADU construction has grown rapidly in recent years, and it's easy to understand why. California state law now makes it easier for homeowners to build these secondary units, and local municipalities like San Jose have supported the trend as a way to address housing needs. Whether you want to build a detached backyard cottage, a garage conversion, or an attached addition, ADU construction offers greater control over how your property functions.

At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction project. Our team understands the local permitting process, the engineering considerations, and the design choices that make an ADU functional. If you've been thinking about 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 engineering, filing for, and completing 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 entrance — that is located on the same parcel 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 property boundaries, available square footage, and infrastructure capacity. From there, blueprints are prepared and submitted to the city for permit approval. Once approvals are in place, ADU construction moves into the more info physical build phase — which encompasses site preparation, framing, mechanical systems, weatherproofing, and interior finishing. 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 depth of planning at every stage. Materials must be selected to complement the existing structure. Systems like wiring and water supply must be built for long-term residential demand. Brother & Brother Builders approaches every build with the same professional rigor we bring to full custom home projects.

Key Advantages ADU Construction

• Higher Resale Potential — ADU construction delivers real market value to your property, often generating strong equity gains when it's time to sell.
• Revenue Generation — A completed ADU may be listed 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 self-contained residence without moving to another neighborhood.
• Customization Options — From open-plan one-bedrooms, ADU construction is adaptable to the intended occupant's lifestyle.
• Faster Permitting in California — Recent state legislation has reduced the red tape associated with ADU construction, resulting in a timeline that is faster and more affordable than ever before.
• Sustainable Land Use — Building an ADU uses your existing lot instead of requiring new development, which aligns with sustainability goals.
• Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction creates a truly separate unit where tenants live autonomously.
• Long-Term Investment Security — A well-built ADU continues to produce returns for many years and generates both livable square footage and monetary benefit.

The ADU Construction Journey Step by Step

1. Property Walkthrough and Feasibility Check — Our builders assess your property to evaluate setbacks, lot coverage limits, and utility connections. This phase answers exactly what's possible before any time is invested in drawings.
2. Architectural Drafting and Space Planning — Experienced draftspeople create precise architectural drawings tailored to your needs. Every square foot is planned to maximize function and livability.
3. Permit Submission and Municipal Review — ADU construction in San Jose involves filing drawings to the city's building department for inspection and clearance. Brother & Brother Builders coordinates the permitting on your behalf, addressing any city comments promptly.
4. Excavation and Foundation Installation — Once permits are approved, physical construction begins. This involves leveling and prepping the ground, completing foundation work, and running initial plumbing and electrical conduits.
5. Framing, Roofing, and Exterior Work — The structural frame is erected followed by insulation, sheathing, and exterior cladding. During this step, the ADU transforms from a concept to a building.
6. MEP Systems Rough-In — Certified technicians install the water supply, drain lines, and electrical panel that make the ADU operationally complete. Every system is reviewed at each code checkpoint throughout ADU construction.
7. 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 unit is officially approved for use.

Who Is a Good Candidate for ADU Construction?

Property owners who are best suited from ADU construction generally fit within a few recognizable groups. If you have a residential property 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 financially driven ADU construction clients, along with families accommodating adult children who need housing.

You may also be someone who runs a small business and wants a detached creative or business space that is distinct from your family's daily life. Property investors and rental owners 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 sites with unusual utility access challenges. Very small lots or properties with easements may need a modified approach. Our experts will evaluate 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 total process for ADU construction typically ranges from six to fourteen months, based on the project scope and how quickly approvals come through. Permitting 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 may complete more quickly, while custom detached builds require more time.

What does ADU construction usually run in terms of budget?

Costs vary widely based on whether it's a conversion or new construction. For most projects in this region, ADU construction commonly costs $150,000 to $400,000 or more for a detached new build. Interior conversion projects tend to cost less, sometimes in the $80,000 to $150,000 range. A detailed estimate can only be produced following a full site assessment.

Is ADU construction difficult to live through while it's underway?

The day-to-day impact depends on where the ADU is being built. Standalone ADU projects are typically less disruptive, since the crew operates at a distance from your living areas. Interior conversions may create short-term inconveniences during key milestones. Our team communicates clearly about what to expect at each stage.

Do I need to move out during ADU construction?

Generally speaking, you are not required to vacate your house during ADU construction. The vast majority of projects are structured to allow you continue living in the home throughout the process. Certain situations could require a brief departure if interior conversion work touches shared systems in ways that temporarily impact livability. The team at Brother & Brother Builders will flag these situations during the pre-construction consultation.

How long will an ADU built through professional ADU construction remain in good condition?

An ADU constructed with quality materials is designed to last as long as any standard residential structure — indefinitely with proper upkeep. How long it lasts comes down to the quality of materials used, how well routine maintenance is performed, and if mechanical components are maintained on schedule. Our builds use high-quality components and comply with all local building codes to deliver a structure that stands the test of time.

ADU Construction for San Jose Homeowners

The communities throughout San Jose provide a wide range of property types that are perfectly suited for ADU construction. Property owners near the Almaden Valley area often discover their properties work well for both attached and detached projects. The Berryessa area are increasingly popular for ADU construction as families expand. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has project experience in the area.

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 the San Jose permitting environment means fewer surprises from kickoff through certificate of occupancy.

Schedule Your ADU Construction Planning Session Today

If you're ready to move forward with ADU construction, Brother & Brother Builders is here to help. Our experts offer years of hands-on experience in ADU construction including all types of project types — from small attached additions to fully independent secondary homes. The process begins with a comprehensive site assessment where we listen to your goals and give you a realistic picture of what's achievable.

Reach out to our team to set up your consultation. Whether you're in the early stages of planning, we're glad to answer questions, share examples of our work and make sure you feel confident before committing. 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