Expand Your Home with Quality ADU Construction
Property owners throughout San Jose, CA are realizing that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction provides a powerful 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 precision and transparency.
The interest in ADU construction has grown rapidly in recent years, and it's easy to understand why. California state law has simplified the process for homeowners to construct these secondary units, and local municipalities like San Jose have encouraged the trend as a way to increase density responsibly. 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 works.
At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction project. Our team understands the local permitting process, the engineering requirements, and the design choices that make an ADU functional. When you're ready to explore what ADU construction could mean for your property, this guide explains everything you need to know.
What Is the ADU Construction Process?
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 complete living space — including 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 below-grade dwelling units.
Mechanically, the process begins with a detailed site assessment, where our professionals evaluate property boundaries, available square footage, and infrastructure capacity. From there, architectural drawings are prepared and submitted to the city for permit approval. Once the paperwork is cleared, ADU construction moves into the physical build phase — which encompasses site preparation, framing, roofing, plumbing, electrical, insulation. The result is a move-in-ready living unit attached to or separate from your main home.
What sets quality ADU construction apart is the level of craftsmanship at every stage. Products need to be chosen to complement the existing structure. Systems like plumbing and electrical must be sized for independent daily use. Brother & Brother Builders handles every ADU construction job with the same technical discipline we apply to large-scale custom home projects.
Key Reasons to Choose 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.
- Rental Income Potential — A completed ADU is leasable as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
- Space for Loved Ones — ADU construction offers family members a comfortable home of their own without moving to another neighborhood.
- Customization Options — From modern studio layouts, ADU construction may be customized to your household's priorities.
- Simplified Regulatory Path — Recent state legislation has minimized the barriers and delays associated with ADU construction, resulting in a timeline that is faster and less expensive than ever before.
- Efficient Use of Your Lot — Building an ADU maximizes the land you already own instead of consuming open land, which contributes to sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where residents have their own space.
- Long-Term Investment Security — A well-built ADU continues to produce returns for many years and generates both functional space and financial upside.
The ADU Construction Process Step by Step
- Site Evaluation and Zoning Analysis — Our builders assess your property to evaluate setbacks, lot coverage limits, and utility connections. This step tells you exactly what ADU types will work before any resources go toward planning.
- Architectural Drafting and Space Planning — Experienced draftspeople create precise architectural drawings tailored to your needs. Layouts are carefully considered to maximize function and livability.
- Permit Submission and Municipal Review — ADU construction in San Jose involves filing drawings to the city's building department for sign-off and verification. Our team handles all submissions on your behalf, addressing any city comments promptly.
- Ground Prep and Structural Base — Once permits are approved, physical construction begins. This includes grading the site, pouring the concrete foundation, and running initial plumbing and electrical conduits.
- Structural Framing and Weatherproofing — The structural frame is erected followed by weatherproofing and exterior finish materials. This phase, the ADU becomes recognizable as a structure.
- MEP Systems Rough-In — Certified technicians install the heating, cooling, drainage, and power infrastructure that make the ADU fully functional. All work is inspected at required milestones throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Trim, appliances, tile, and lighting are placed and inspected to the approved plan. A last official inspection confirms the unit is code-compliant and the ADU is ready 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 in a good starting place. Homeowners wanting to add a revenue stream through rental are among the most motivated ADU construction clients, along with families accommodating adult children who need housing.
Another strong candidate is someone who works from home and wants a separate office or studio space that remains away 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.
Those who should discuss alternatives first include lots that are below minimum size thresholds. Sites with underground infrastructure conflicts may need a modified approach. 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 typically take from start to finish?
The total process for ADU construction usually runs between six to fourteen months, influenced by the type of unit being built 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 custom detached builds require more time.
What does ADU construction usually run in terms of budget?
Costs vary widely based on project complexity and finishes selected. For most projects in this region, ADU construction commonly costs $150,000 to $400,000 or more for a fully custom construction. Interior conversion projects tend to cost less, sometimes between $75,000 and $140,000. An accurate budget can only be developed after a thorough property review.
Is ADU construction difficult to live through while it's underway?
The level of disruption depends on where the ADU is being built. Detached backyard builds are generally the least intrusive, since the crew operates at a distance from your living areas. Garage conversions or attached additions may involve some shared wall work during specific stages like framing or MEP rough-in. We provide advance notice about any phases that may affect your routine.
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 set up to let you stay in your primary unit throughout the build. Exceptions may arise if major utility upgrades affect the main house in ways that briefly affect habitability. Our project managers will discuss these scenarios during the pre-construction consultation.
How long will an ADU built through professional ADU construction hold up?
A well-built ADU should last as long as the main residence — indefinitely with proper upkeep. Longevity is tied to the systems installed, whether the unit is properly cared for, and if mechanical components are maintained on schedule. Our builds use residential-grade products rated for longevity and follow all code requirements to deliver a structure that stands the test of time.
ADU Construction for San Jose Homeowners
Residential areas across San Jose present a variety of property types that are perfectly suited for ADU construction. Property owners near the Almaden Valley area frequently see their parcels work well for both attached and detached projects. The Berryessa area have seen growing ADU activity as multigenerational living becomes more common. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team knows the permitting landscape well.
San Jose's permitting office 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 smoother project delivery from design through the final walkthrough.
Book Your ADU Construction Consultation Today
If you're ready to add an ADU to your property, Brother & Brother Builders is here to help. Our experts offer proven skills in ADU construction for many different project types — from small attached additions to fully independent secondary homes. Every project starts with a thorough and honest property review where we understand your vision and share clear expectations of what's achievable.
Reach out to our team to schedule a site visit. Whether you're in the early stages of planning, we're glad to adu construction near me discuss timelines, costs, and design possibilities and give you the clarity you need to move forward. This type of project is a meaningful commitment — and we're committed to helping you get it right.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632