Unlock New Space with Expert ADU Construction
Homeowners across San Jose, CA are finding that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction creates a flexible new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has supported hundreds of local homeowners turn these plans to life with skill and care.
The interest in ADU construction has increased significantly in recent years, and it's no mystery. California state law now makes it easier for homeowners to construct these secondary units, and local municipalities like San Jose have embraced the trend as a way to expand the housing supply. Whether you're building a detached backyard cottage, a garage conversion, or an attached addition, ADU construction offers greater control over how your property serves your household.
At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction project. Our team is familiar with city and county requirements, the engineering considerations, and the aesthetic decisions that make an ADU truly livable. Should you want to learn about what ADU construction could do for your property, this guide explains everything you need to know.
What Is the ADU Construction Process?
ADU construction describes 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 is located on the same parcel 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 comprehensive review of your lot, where our builders evaluate property boundaries, available square footage, and infrastructure capacity. From there, architectural drawings are prepared and submitted to the city for permit approval. Once permits are secured, ADU construction transitions to the physical build phase — which encompasses site preparation, framing, HVAC, drywall, flooring, and exterior finishes. The result is a fully functional living unit attached to or separate 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 match the primary home's aesthetic. Systems like wiring and water supply must be designed to handle full-time occupancy. Brother & Brother Builders handles every ADU construction job with the same professional rigor we apply to large-scale custom home projects.
Key Benefits ADU Construction
- Boosted Home Equity — ADU construction delivers real market value to your property, often returning more than the build cost when it's time to sell.
- Monthly Cash Flow — A completed ADU is leasable as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
- Housing for Extended Family — ADU construction offers family members a comfortable home of their own without losing proximity to the family.
- Customization Options — From two-bedroom configurations, ADU construction can be tailored to your specific needs.
- Faster Permitting in California — Recent state legislation has minimized the red tape associated with ADU construction, resulting in a timeline that is faster and more cost-efficient than ever before.
- Sustainable Land Use — Building an ADU maximizes the land you already own instead of requiring new development, which supports broader sustainability goals.
- Separate Entrances and Spaces — 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 holds its value for many years and generates both functional space and financial upside.
The ADU Construction Journey Step by Step
- Property Walkthrough and Feasibility Check — Our experts review your property to analyze zoning rules, slope conditions, and available square footage. This phase answers exactly what ADU types will work before any time is invested in drawings.
- Custom Design and Architectural Planning — Experienced draftspeople create precise architectural drawings reflecting your priorities. Layouts are carefully considered to create practical, comfortable living.
- Permitting and City Approval — 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, responding to review feedback promptly.
- Excavation and Foundation Installation — Once permits are approved, physical construction begins. This involves leveling and prepping the ground, completing foundation work, and establishing utility connections.
- Structural Framing and Weatherproofing — Walls and roof systems go up followed by weatherproofing and exterior finish materials. At this stage, the ADU takes its visible shape.
- MEP Systems Rough-In — Certified technicians install the water supply, drain lines, and electrical panel that make the ADU operationally complete. Inspections are completed at designated stages throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Flooring, cabinetry, fixtures, paint are installed and finished to your specifications. A closing municipal review issues the certificate of occupancy and your new space is cleared for use.
Who Is a Right Fit for ADU Construction?
Property owners who are best suited from ADU construction often belong to a few common profiles. If you are a homeowner with enough lot space click here to meet setback requirements, 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.
You may also be someone who runs a small business and wants a separate office or studio space that remains away from your family's daily life. Real estate-minded homeowners who already own residential properties are also well suited for ADU construction, since the return on investment is well-documented.
Homeowners who may want to pause and evaluate include properties with significant setback limitations. Parcels in historic districts or HOA-restricted communities may need a modified approach. Brother & Brother Builders reviews each property on its own merits to recommend the right path forward.
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, based on the project scope and local permitting timelines. The approval phase alone can take several months in San Jose, so starting early is important. Simpler garage conversions may complete more quickly, while custom detached builds 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. In the San Jose area, ADU construction typically ranges from $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 developed after a formal feasibility evaluation.
Is ADU construction difficult to live through while it's underway?
How much the build affects daily life depends on whether you're converting existing space or building new. Standalone ADU projects are usually easier to live alongside, since the construction zone is separate. Interior conversions may require temporary access during specific stages like framing or MEP rough-in. Brother & Brother Builders keeps you informed about upcoming work and timelines.
Do I need to move out during ADU construction?
Generally speaking, you won't have to vacate your main home during ADU construction. The vast majority of projects are designed so that you stay in your primary unit throughout the construction timeline. Certain situations could require a brief departure if interior conversion work touches shared systems in ways that briefly affect habitability. The team at Brother & Brother Builders will discuss these scenarios during the kickoff meeting.
How long will an ADU built through professional ADU construction hold up?
An ADU constructed with quality materials should last as long as any standard residential structure — indefinitely with proper upkeep. Longevity is tied to the standard of construction, how consistently minor repairs are addressed, and if mechanical components are maintained on schedule. We select high-quality components and comply with all local building codes to protect your investment for the long haul.
ADU Construction for Local Homeowners
The communities throughout San Jose provide a diverse mix of property types that are well suited for ADU construction. Homeowners in the Willow Glen neighborhood have found their lots accommodate detached backyard units nicely. Communities around the Capitol Expressway corridor have seen growing ADU activity as housing demand rises. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has likely worked nearby.
San Jose's permitting office follows defined procedures for ADU construction that require a builder familiar with local expectations. Location near major arterials like Story Road or Tully Road can influence utility connection requirements for a given ADU project. Brother & Brother Builders' experience across these local conditions means fewer surprises from the first meeting to the final inspection.
Book Your ADU Construction Consultation Today
When you want to move forward with ADU construction, Brother & Brother Builders is here to help. Our experts offer years of hands-on experience in ADU construction across a wide range of project types — from modest studio builds to large custom detached cottages. Every project starts with a thorough and honest property review where we listen to your goals and give you a realistic picture of what's achievable.
Get in touch with our office to begin the conversation. Whether you're in the early stages of planning, we enjoy answer questions, share examples of our work and help you take the next step. 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