Expand Your Home with Expert ADU Construction
Property owners throughout San Jose, CA are discovering that adding an accessory dwelling unit is one of the most rewarding 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 turn these plans to life with precision and care.
The popularity of ADU construction has increased significantly in recent years, and it's not hard to see why. California state law has simplified the process for homeowners to add these secondary units, and local municipalities like San Jose have encouraged the trend as a way to expand the housing supply. 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 draw on extensive hands-on experience to every ADU construction job. Our team is familiar with city and county requirements, the engineering requirements, and the aesthetic decisions that make an ADU beautiful. When you're ready to explore what ADU construction could mean for your property, this click here guide will walk you through everything you need to know.
What Is ADU Construction?
ADU construction refers to 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 — equipped with a kitchen, bathroom, sleeping area, and its own entryway — that exists on the same lot 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 comprehensive review of your lot, where our builders evaluate property boundaries, available square footage, and infrastructure capacity. 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 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 match the primary home's aesthetic. Systems like HVAC and drainage 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 Benefits ADU Construction
- Higher Resale Potential — ADU construction adds measurable market value to your property, often generating strong equity gains when it's time to sell.
- Revenue Generation — 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 provides adult children a comfortable home of their own without losing proximity to the family.
- Personalized Layouts — From open-plan one-bedrooms, ADU construction is adaptable to your household's priorities.
- Streamlined Approval Process — Recent state legislation has minimized the barriers and delays associated with ADU construction, making the process that is faster and more cost-efficient than ever before.
- Responsible Property Development — Building an ADU works within your current footprint instead of requiring new development, which contributes to sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where occupants have full privacy.
- Durable Return on Investment — A well-built ADU continues to produce returns for the long haul by offering both functional space and financial upside.
The ADU Construction Procedure Step by Step
- Site Evaluation and Zoning Analysis — Our experts review your property to determine what type of ADU is allowed and where it can be placed. This phase answers exactly what can be built before any time is invested in drawings.
- Blueprint Development and Layout Design — Experienced draftspeople create precise architectural drawings reflecting your priorities. Every square foot is planned to optimize daily use.
- Permit Submission and Municipal Review — 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.
- Excavation and Foundation Installation — Once permits are issued, physical construction begins. This includes grading the site, completing foundation work, and establishing utility connections.
- Structural Framing and Weatherproofing — The structural frame is erected followed by weatherproofing and exterior finish materials. This phase, the ADU transforms from a concept to a building.
- Mechanical, Electrical, and Plumbing Installation — Skilled tradespeople install the plumbing lines, electrical wiring, and HVAC systems that make the ADU operationally complete. Every system is reviewed at designated stages throughout ADU construction.
- Interior Finishing and Final Inspections — Flooring, cabinetry, fixtures, paint are placed and inspected to your specifications. A final city inspection confirms the unit is code-compliant and the ADU is ready for use.
Who Is a Strong Candidate for ADU Construction?
Homeowners who benefit most from ADU construction generally fit within a few clear categories. If you are a homeowner with a backyard, garage, or basement that could be converted, 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 supporting elderly parents.
Another strong candidate is someone who runs a small business and wants a separate office or studio space that is distinct from your family's daily life. Property investors and rental owners who are building a portfolio are also a natural fit 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 face additional constraints. Our experts will evaluate each property case by case to provide realistic options.
ADU Construction Common Questions Answered
How long does ADU construction typically take from start to finish?
The full timeline for ADU construction commonly spans six to fourteen months, depending on design complexity and how quickly approvals come through. City review on its own can take several months in San Jose, so starting early is important. Smaller detached units often finish in the lower end of the range, while custom detached builds require more time.
What does ADU construction usually run in terms of budget?
Pricing depends on many factors 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 standalone backyard unit. Interior conversion projects 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 where the ADU is being built. Detached backyard builds are typically less disruptive, since the crew operates at a distance from your living areas. Garage conversions or attached additions may involve some shared wall work during certain phases of construction. We provide advance notice about upcoming work and timelines.
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 remain on the property throughout the construction timeline. Certain situations could require a brief departure if interior conversion work touches shared systems in ways that temporarily impact livability. Our construction supervisors will walk you through any potential disruptions during the planning phase.
How long will an ADU built through professional ADU construction remain in good condition?
Any ADU built to code with professional oversight is designed to last as long as the main residence — often several decades with routine maintenance. Durability depends to the systems installed, whether the unit is properly cared for, and how proactively issues are resolved over time. Our builds use residential-grade products rated for longevity and follow all code requirements to ensure lasting performance.
ADU Construction for Local Homeowners
Residential areas across San Jose present a diverse mix of property types that are perfectly suited for ADU construction. Homeowners in the Willow Glen neighborhood frequently see their parcels are well configured for ADU builds. The Berryessa area are increasingly popular for ADU construction as families expand. Whether your property is near downtown San Jose, our team knows the permitting landscape well.
Local regulatory bodies in this area has developed specific protocols for ADU construction that require a builder familiar with local expectations. Access to infrastructure along thoroughfares like Monterey Road can impact the design approach for a given ADU project. Brother & Brother Builders' experience across these local conditions means fewer surprises from the first meeting to the final inspection.
Schedule Your ADU Construction Assessment Today
Should you be thinking about how to move forward with ADU construction, Brother & Brother Builders is here to help. We bring licensed expertise in ADU construction for many different project types — from modest studio builds to fully independent secondary homes. Our approach opens with a comprehensive site assessment where we listen to your goals and give you a realistic picture of what ADU construction on your property will look like.
Reach out to our team to set up your consultation. Even if you're just exploring the idea, our team is happy to walk through your options, review completed projects and help you take the next step. 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