Brother & Brother Builders

Unlock New Space with Expert ADU Construction

Families in San Jose, CA are discovering that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction creates a powerful new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has helped hundreds of local homeowners bring these projects to life with craftsmanship and integrity.

The popularity of ADU construction has surged in recent years, and it's no mystery. 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 gives you more control over how your property functions.

At Brother & Brother Builders, we apply deep hands-on experience to every ADU construction build. Our team understands the local permitting process, the engineering requirements, and the planning steps that make an ADU beautiful. When you're ready to explore what ADU construction could mean for your property, this guide will walk you through 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 fully independent living space — featuring a kitchen, bathroom, sleeping area, and its own entryway — 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 basement or interior conversions.

Mechanically, the work starts with a comprehensive review of your lot, where our builders evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, blueprints are prepared and submitted to the relevant municipal authority. Once approvals are in place, ADU construction enters the physical build phase — which includes foundation work, framing, mechanical systems, weatherproofing, and interior finishing. 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 attention to detail 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 treats each project with the same technical discipline we click here use on major custom home projects.

Key Benefits ADU Construction

• Boosted Home Equity — ADU construction contributes significant 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, generating steady monthly revenue for the homeowner.
• Housing for Extended Family — ADU construction provides adult children a private, independent living space without moving to another neighborhood.
• Personalized Layouts — From modern studio layouts, ADU construction is adaptable to the intended occupant's lifestyle.
• Simplified Regulatory Path — Recent state legislation has minimized the permitting obstacles associated with ADU construction, creating a path that is faster and more affordable than ever before.
• Efficient Use of Your Lot — Building an ADU maximizes the land you already own instead of expanding urban sprawl, which supports broader sustainability goals.
• Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where tenants live autonomously.
• Long-Term Investment Security — A well-built ADU holds its value for decades, providing both functional space and financial upside.

The ADU Construction Process Step by Step

1. Initial Property Assessment and Feasibility Review — Our builders assess your property to determine what type of ADU is allowed and where it can be placed. This step tells you exactly what's possible before any money is spent on design.
2. Blueprint Development and Layout Design — Our design team create comprehensive blueprints reflecting your priorities. Space is thoughtfully allocated to optimize daily use.
3. Permitting and City Approval — ADU construction in San Jose involves filing drawings to the city's building department for sign-off and verification. We manage this entire process on your behalf, addressing any city comments promptly.
4. Site Preparation and Foundation Work — Once permits are issued, on-site work kicks off. This covers land preparation, pouring the concrete foundation, and running initial plumbing and electrical conduits.
5. Framing, Roofing, and Exterior Work — Framing is completed followed by weatherproofing and exterior finish materials. At this stage, the ADU becomes recognizable as a structure.
6. Mechanical, Electrical, and Plumbing Installation — Certified technicians install the heating, cooling, drainage, and power infrastructure that make the ADU ready for occupancy. Inspections are completed at designated stages throughout ADU construction.
7. Interior Finishing and Final Inspections — Flooring, cabinetry, fixtures, paint are installed and finished to the approved plan. A last official inspection grants legal occupancy status and the unit is officially approved 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 have a residential property with available square footage under zoning rules, you're already well-positioned. Homeowners wanting to add a revenue stream through rental are among the most financially driven ADU construction clients, along with families accommodating adult children who need housing.

Another strong candidate is someone who needs a dedicated professional workspace and wants a detached creative or business space that doesn't interfere with your family's daily life. Landlords and real estate investors who are building a portfolio are also well suited for ADU construction, since the long-term value is proven.

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 team can assess each property on its own merits to provide realistic options.

ADU Construction Frequently Asked Questions

How long does ADU construction usually take from start to finish?

The complete duration for ADU construction commonly spans six to fourteen months, depending on design complexity and city review schedules. Permitting alone can take several months in San Jose, so planning ahead matters. Straightforward interior conversions can move faster, while larger new construction ADUs fall toward the upper end of the timeline.

What does ADU construction usually run in terms of budget?

Costs vary widely 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 detached new build. Attached ADU additions often come in under, sometimes between $75,000 and $140,000. A precise cost projection 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 the project's location on your property. Standalone ADU projects are usually easier to live alongside, since the crew operates at a distance from your living areas. Interior conversions may require temporary access during certain phases of construction. We provide advance notice about any phases that may affect your routine.

Do I need to vacate the property during ADU construction?

In most cases, you are not required to vacate your house during ADU construction. Most builds are structured to allow you continue living in the home throughout the construction timeline. Certain situations could require a brief departure if significant structural connections require temporary shutoffs in ways that briefly affect habitability. Our project managers will discuss these scenarios 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 can be expected to last as long as your primary home — indefinitely with proper upkeep. Longevity is tied to the systems installed, how consistently minor repairs are addressed, and whether systems like roofing and plumbing are serviced regularly. Our builds use high-quality components and build to current California residential standards to ensure lasting performance.

ADU Construction for Local Homeowners

The communities throughout San Jose provide a wide range of property types that are well suited for ADU construction. Residents in the Rose Garden district often discover their properties accommodate detached backyard units nicely. Neighborhoods near Blossom Hill Road are seeing more homeowners add secondary units 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 influence utility connection requirements 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 Planning Session Today

When you want to move forward with ADU construction, Brother & Brother Builders is here to help. Our experts offer proven skills in ADU construction for many different project types — from simple garage conversions to large custom detached cottages. The process begins with a detailed, no-pressure consultation where we learn what you're trying to accomplish and share clear expectations of what the project will involve.

Reach out to our team to set up your consultation. Even if you're just exploring the idea, we're glad to discuss timelines, costs, and design possibilities and make sure you feel confident before committing. Building an ADU is a major decision — and we're committed to helping you get it right.

Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632