Expert ADU Construction Services for Homeowners

Unlock New Space with Expert ADU Construction

Families in San Jose, CA are realizing that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction provides a powerful new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has guided hundreds of local homeowners bring these projects to life with craftsmanship and transparency.

The interest in ADU construction has increased significantly in recent years, and it's not hard to see why. California state law has streamlined permitting for homeowners to construct these secondary units, and local municipalities like San Jose have encouraged 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 works.

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 details, and the aesthetic decisions that make an ADU functional. Should you want to learn about what ADU construction could mean 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 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 includes various structural types, including detached backyard units, attached additions, garage conversions, and even basement or interior conversions.

Mechanically, the process begins with a comprehensive review of your lot, where our professionals evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, design plans are prepared and submitted to the local building department. Once permits are secured, ADU construction moves into the physical build phase — which encompasses site preparation, framing, mechanical systems, weatherproofing, and interior finishing. The result is a completely finished living unit adjacent to or detached from your main home.

What separates excellent ADU construction from an average project is the level of craftsmanship at every stage. Components should be specified to complement the existing structure. Systems like plumbing and electrical must be designed to handle full-time occupancy. Brother & Brother Builders handles every ADU construction job with the same high standards we use on major custom home projects.

Key Reasons to Choose ADU Construction

• Increased Property Value — ADU construction contributes significant market value to your property, often returning more than the build cost when it's time to sell.
• Rental Income Potential — A completed ADU is leasable as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
• Multi-Generational Living — ADU construction gives aging parents a private, independent living space without losing proximity to the family.
• Customization Options — From open-plan one-bedrooms, ADU construction may be customized to your household's priorities.
• Simplified Regulatory Path — Recent state legislation has cut down 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 works within your current footprint instead of requiring new development, which supports broader sustainability goals.
• Privacy for All Residents — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where tenants live autonomously.
• Durable Return on Investment — A well-built ADU remains an asset for decades, providing both livable square footage and monetary benefit.

The ADU Construction Procedure Step by Step

1. Initial Property Assessment and Feasibility Review — Our team visits your property to analyze zoning rules, slope conditions, and available square footage. This stage clarifies exactly what's possible before any time is invested in drawings.
2. Blueprint Development and Layout Design — Experienced draftspeople create comprehensive blueprints tailored to your needs. Layouts are carefully considered 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 review and approval. Brother & Brother Builders coordinates the permitting on your behalf, resolving any revision requests promptly.
4. Excavation and Foundation Installation — Once permits are issued, on-site work kicks off. This includes grading the site, completing foundation work, and setting up utilities.
5. Framing, Roofing, and Exterior Work — Framing is completed followed by insulation, sheathing, and exterior cladding. This phase, the ADU takes its visible shape.
6. Interior Systems and Infrastructure — Skilled tradespeople install the water supply, drain lines, and electrical panel that make the ADU operationally complete. Inspections are completed at each code checkpoint throughout ADU construction.
7. Interior Completion and City Sign-Off — Countertops, hardware, finishes, and fixtures are placed and inspected to your specifications. A final city inspection issues the certificate of occupancy and the ADU is ready for use.

Who Is a Strong Candidate for ADU Construction?

Homeowners who benefit most from ADU construction typically fall into a few clear categories. If you own a single-family home with available square footage under zoning rules, you're already in a good starting place. Homeowners hoping to offset mortgage costs through rental are among the most financially driven ADU construction clients, along with families navigating multigenerational living situations.

Another strong candidate is someone who runs a small business and wants a separate office or studio space that remains away from your family's daily life. Landlords and real estate investors who want to maximize their land are also a natural fit for ADU construction, since the long-term value is proven.

Situations where ADU construction may not be the best first step include properties with significant setback limitations. Very small lots or properties with easements may require additional review. Our experts will evaluate each property case by case to advise you on what's feasible.

ADU Construction Frequently Asked Questions

How long does ADU construction typically take from start to finish?

The total process for ADU construction commonly spans six to fourteen months, depending on design complexity and how quickly approvals come through. The approval phase alone can take two to four months in San Jose, so beginning the process sooner rather than later is wise. Smaller detached units may complete more quickly, while larger new construction ADUs take longer to complete.

What does ADU construction typically cost?

Budget requirements differ 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 standalone backyard unit. Attached ADU additions are generally priced lower, sometimes starting around $80,000 depending on scope. A precise cost projection can only be produced following a thorough property review.

Is ADU construction intrusive while it's underway?

The day-to-day impact depends on whether you're converting existing read more space or building new. New construction in the rear yard are usually easier to live alongside, since work happens away from the main house. Interior conversions may involve some shared wall work during certain phases of construction. Brother & Brother Builders keeps you informed about what to expect at each stage.

Do I need to leave my home during ADU construction?

For the majority of homeowners, you won't have to vacate your main home during ADU construction. Most job sites are structured to allow you continue living in the home throughout the build. There are edge cases if interior conversion work touches shared systems in ways that briefly affect habitability. 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 last?

A well-built ADU should last as long as the main residence — indefinitely with proper upkeep. How long it lasts comes down to the quality of materials used, whether the unit is properly cared for, and if mechanical components are maintained on schedule. We select commercial-grade materials and build to current California residential standards 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. Homeowners in the Willow Glen neighborhood often discover their properties are well configured for ADU builds. Communities around the Capitol Expressway corridor are seeing more homeowners add secondary units as housing demand rises. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team knows the permitting landscape well.

The City of San Jose's building department follows defined procedures for ADU construction that our team navigates routinely. Access to infrastructure along thoroughfares like Monterey Road can affect how quickly permits are approved for a given ADU project. Brother & Brother Builders' experience across this region's building landscape means smoother project delivery from the first meeting to the final inspection.

Book Your ADU Construction Assessment Today

Should you be thinking about how to explore what an ADU could look like on your lot, Brother & Brother Builders is here to help. Our experts offer licensed expertise in ADU construction across a wide range of project types — from small attached additions to fully independent secondary homes. Our approach opens with a detailed, no-pressure consultation where we understand your vision and give you a realistic picture of what's achievable.

Reach out to our team to set up your consultation. No matter where you are in the decision-making process, we enjoy answer questions, share examples of our work 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