Unlock New Space with Professional ADU Construction
Families in San Jose, CA are realizing that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction opens the door to a flexible new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has guided hundreds of local homeowners bring these projects to life with craftsmanship and care.
The demand for ADU construction has increased significantly in recent years, and it's no mystery. California state law has simplified the process 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 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 considerations, and the planning steps that make an ADU functional. When you're ready to explore what ADU construction could do for your property, this guide covers everything you need to know.
What Is the ADU Construction Process?
ADU construction refers to the process of designing, permitting, and building an accessory dwelling unit on a residential property. An accessory dwelling unit is a self-contained living space — including a kitchen, bathroom, sleeping area, and its own access point — 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 below-grade dwelling units.
Mechanically, everything kicks off with a thorough property evaluation, where our professionals evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, blueprints are prepared and submitted to the relevant municipal authority. Once permits are secured, ADU construction enters the physical build phase — which covers everything from foundational work, framing, mechanical systems, weatherproofing, and interior finishing. The result is a completely more info finished living unit adjacent to or detached from your main home.
The difference between a good and a great ADU build is the attention to detail at every stage. Products need to be chosen to align with the neighborhood's character. Systems like wiring and water supply must be sized for independent daily use. Brother & Brother Builders approaches every build with the same professional rigor we apply to large-scale custom home projects.
Key Benefits ADU Construction
- Increased Property Value — ADU construction delivers real market value to your property, often returning more than the build cost when it's time to sell.
- Revenue Generation — A completed ADU may be listed as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
- Space for Loved Ones — ADU construction provides adult children a comfortable home of their own without losing proximity to the family.
- Customization Options — From two-bedroom configurations, ADU construction is adaptable to your specific needs.
- Simplified Regulatory Path — Recent state legislation has cut down the barriers and delays associated with ADU construction, resulting in a timeline that is faster and more cost-efficient than ever before.
- Sustainable Land Use — Building an ADU works within your current footprint instead of expanding urban sprawl, which contributes to sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where residents have their own space.
- Lasting Financial Benefit — A well-built ADU continues to produce returns for the long haul by offering both functional space and financial upside.
The ADU Construction Journey Step by Step
- Initial Property Assessment and Feasibility Review — Our team visits your property to determine what type of ADU is allowed and where it can be placed. This stage clarifies exactly what ADU types will work before any resources go toward planning.
- Blueprint Development and Layout Design — Experienced draftspeople create precise architectural drawings reflecting your priorities. Every square foot is planned to maximize function and livability.
- Permit Submission and Municipal Review — ADU construction in San Jose demands documentation to the city's building department for review and approval. Brother & Brother Builders coordinates the permitting on your behalf, addressing any city comments promptly.
- Site Preparation and Foundation Work — Once permits are approved, physical construction begins. This covers land preparation, laying the structural base, and establishing utility connections.
- Structural Framing and Weatherproofing — Framing is completed followed by insulation, sheathing, and exterior cladding. During this step, the ADU takes its visible shape.
- MEP Systems Rough-In — Licensed subcontractors install the heating, cooling, drainage, and power infrastructure that make the ADU fully functional. Inspections are completed at designated stages throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Trim, appliances, tile, and lighting are placed and inspected to the agreed design. A last official inspection issues the certificate of occupancy and the unit is officially approved for use.
Who Is a Right Fit for ADU Construction?
People who see the greatest return from ADU construction generally fit within a few clear categories. If you are a homeowner with available square footage under zoning rules, you're already a strong candidate. Homeowners hoping to offset mortgage costs through rental are among the most financially driven ADU construction clients, along with families supporting elderly parents.
You may also be someone who works from home and wants a separate office or studio space that is distinct from your family's daily life. Property investors and rental owners who already own residential properties 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 properties with significant setback limitations. Parcels in historic districts or HOA-restricted communities may face additional constraints. Brother & Brother Builders reviews each property on its own merits to advise you on what's feasible.
ADU Construction Frequently Asked Questions
How long does ADU construction usually take from start to finish?
The full timeline for ADU construction usually runs between six to fourteen months, based on the project scope and how quickly approvals come through. Permitting alone can take two to four months in San Jose, so planning ahead matters. Simpler garage conversions can move faster, while larger new construction ADUs fall toward the upper end of the timeline.
What does ADU construction typically cost?
Budget requirements differ based on whether it's a conversion or new construction. For most projects in this region, ADU construction generally falls between $150,000 to $400,000 or more for a fully custom construction. Interior conversion projects are generally priced lower, sometimes starting around $80,000 depending on scope. An accurate budget can only be given after completing a thorough property review.
Is ADU construction intrusive while it's underway?
How much the build affects daily life depends on where the ADU is being built. New construction in the rear yard are usually easier to live alongside, since the crew operates at a distance from your living areas. Projects that connect to the main structure may create short-term inconveniences during specific stages like framing or MEP rough-in. Brother & Brother Builders keeps you informed about any phases that may affect your routine.
Do I need to move out during ADU construction?
Generally speaking, you won't have to vacate your primary residence during ADU construction. Most builds are designed so that you remain on the property throughout the construction timeline. Certain situations could require a brief departure if significant structural connections require temporary shutoffs in ways that temporarily impact livability. Our construction supervisors will flag these situations during the kickoff meeting.
How long will an ADU built through professional ADU construction hold up?
Any ADU built to code with professional oversight is designed to last as long as the main residence — typically 50 years or more. How long it lasts comes down to the standard of construction, whether the unit is properly cared for, and how proactively issues are resolved over time. We select commercial-grade materials and build to current California residential standards to deliver a structure that stands the test of time.
ADU Construction for San Jose Homeowners
Residential areas across San Jose present a wide range of property types that are well 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 have seen growing ADU activity 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 follows defined procedures for ADU construction that experienced builders know well. Location near major arterials like Story Road or Tully Road can impact the design approach for a given ADU project. Brother & Brother Builders' experience across the San Jose permitting environment means more accurate timelines and budgets from design through the final walkthrough.
Book Your ADU Construction Assessment Today
When you want to explore what an ADU could look like on your lot, Brother & Brother Builders is ready to guide you. Our builders provide licensed expertise in ADU construction for many different project types — from small attached additions to fully independent secondary homes. Every project starts with a comprehensive site assessment where we learn what you're trying to accomplish and share clear expectations of what the project will involve.
Contact Brother & Brother Builders to begin the conversation. No matter where you are in the decision-making process, we're glad to 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