Unlock New Space with Quality ADU Construction
Homeowners across San Jose, CA are discovering that adding an accessory dwelling unit is one of the most practical 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 precision and integrity.
The demand for ADU construction has surged in recent years, and it's not hard to see why. California state law has simplified the process for homeowners to build these secondary units, and local municipalities like San Jose have embraced 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 provides increased control over how your property functions.
At Brother & Brother Builders, we apply deep hands-on experience to every ADU construction job. Our team understands the local permitting process, the engineering considerations, and the design choices that make an ADU beautiful. Should you want to learn about what ADU construction could do for your property, this guide covers everything you need to know.
What Is ADU Construction?
ADU construction describes 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 exists on the same lot as click here a primary residence. ADU construction includes various structural types, including detached backyard units, attached additions, garage conversions, and even below-grade dwelling units.
Mechanically, everything kicks off with a thorough property evaluation, where our team evaluate setbacks, zoning, utility access, and structural feasibility. 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 includes foundation work, framing, HVAC, drywall, flooring, and exterior finishes. The result is a fully functional living unit connected to or independent of your main home.
The difference between a good and a great ADU build is the attention to detail at every stage. Materials must be selected to complement the existing structure. Systems like plumbing and electrical must be designed to handle full-time occupancy. Brother & Brother Builders approaches every build with the same technical discipline we apply to large-scale custom home projects.
Key Advantages ADU Construction
- Increased Property Value — ADU construction adds measurable market value to your property, often increasing appraised value substantially when it's time to sell.
- Revenue Generation — A completed ADU is leasable as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
- Multi-Generational Living — ADU construction gives aging parents a comfortable home of their own without leaving the property.
- Personalized Layouts — From open-plan one-bedrooms, 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 more affordable than ever before.
- Responsible Property Development — Building an ADU maximizes the land you already own instead of consuming open land, which contributes to sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where tenants live autonomously.
- Durable Return on Investment — A well-built ADU remains an asset for many years and generates both functional space and financial upside.
The ADU Construction Journey 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's possible before any resources go toward planning.
- Custom Design and Architectural Planning — Experienced draftspeople create precise architectural drawings reflecting your priorities. Every square foot is planned to create practical, comfortable living.
- Permitting and City Approval — 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.
- Excavation and Foundation Installation — Once permits are granted, physical construction begins. This includes grading the site, completing foundation work, and setting up utilities.
- Shell Construction and Exterior Finishing — The structural frame is erected followed by roofing, siding, windows, and exterior doors. During this step, the ADU transforms from a concept to a building.
- MEP Systems Rough-In — Licensed subcontractors install the plumbing lines, electrical wiring, and HVAC systems that make the ADU fully functional. Every system is reviewed at each code checkpoint throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are placed and inspected to your specifications. A final city inspection issues the certificate of occupancy and your new space is cleared for use.
Who Is a Strong Candidate for ADU Construction?
Homeowners who benefit most from ADU construction typically fall into a few common profiles. If you have a residential property with available square footage under zoning rules, you're already in a good starting place. Homeowners looking to generate income through rental are among the most common ADU construction clients, along with families navigating multigenerational living situations.
You may also be someone who needs a dedicated professional workspace and wants a detached creative or business space that is distinct from your family's daily life. Landlords and real estate investors who want to maximize their land are also prime candidates for ADU construction, since the long-term value is proven.
Homeowners who may want to pause and evaluate include properties with significant setback limitations. Parcels in historic districts or HOA-restricted communities may require additional review. Our experts will evaluate each property on its own merits to recommend the right path forward.
ADU Construction Common Questions Answered
How long does ADU construction generally take from start to finish?
The complete duration for ADU construction usually runs between six to fourteen months, based on the project scope and local permitting timelines. Permitting alone can take several months in San Jose, so starting early is important. Straightforward interior conversions often finish in the lower end of the range, 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. Locally, ADU construction typically ranges from $150,000 to $400,000 or more for a standalone backyard unit. Interior conversion projects tend to cost less, sometimes starting around $80,000 depending on scope. A precise cost projection can only be produced following 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 usually easier to live alongside, since the construction zone is separate. Interior conversions may involve some shared wall work during key milestones. Our team communicates clearly about upcoming work and timelines.
Do I need to leave my home during ADU construction?
In most cases, you won't have to vacate your main home during ADU construction. Most job sites are set up to let you stay in your primary unit throughout the process. There are edge cases if major utility upgrades affect the main house in ways that require short-term access disruption. The team at Brother & Brother Builders will discuss these scenarios during the kickoff meeting.
How long will an ADU built through professional ADU construction remain in good condition?
A well-built ADU can be expected to last as long as the main residence — indefinitely with proper upkeep. 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 commercial-grade materials and build to current California residential standards to protect your investment for the long haul.
ADU Construction for Local Homeowners
San Jose's neighborhoods offer a wide range of property types that are well suited for ADU construction. Homeowners in the Willow Glen neighborhood often discover their properties work well for both attached and detached projects. The Berryessa area are increasingly popular for ADU construction as housing demand rises. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team knows the permitting landscape well.
Local regulatory bodies in this area applies particular standards for ADU construction that require a builder familiar with local expectations. Access to infrastructure along thoroughfares like Monterey Road can affect how quickly permits are approved for a given ADU project. Our team's knowledge of these local conditions means more accurate timelines and budgets from design through the final walkthrough.
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 ready to guide you. Our experts offer proven skills in ADU construction across a wide range of project types — from small attached additions to large custom detached cottages. Our approach opens with a thorough and honest property review where we understand your vision and share clear expectations of what ADU construction on your property will look like.
Reach out to our team to schedule a site visit. Whether you're in the early stages of planning, we're glad to walk through your options, review completed projects and make sure you feel confident before committing. This type of project is a meaningful commitment — 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