Start with the why.
Rental income, family housing, a guest house or a home office. The goal shapes the design.
Detached backyard units, garage conversions and basement conversions. Preferred Builders designs, permits and builds accessory dwelling units, from design to construction for homes in Millbrae. We handle ADU construction in Millbrae from design to final inspection.
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ADUs are versatile secondary housing units that can serve as guest houses, rental units or additional living space. Our team provides ADU services from design to construction, with customized solutions that meet your needs and complement your home. That is how we approach ADU construction in Millbrae.
Rental income, family housing, a guest house or a home office. The goal shapes the design.
Compare detached, attached, garage conversion and basement options for your lot.
We prepare the plans, work through the City's ADU requirements and secure the permits.
The right ADU depends on your lot, your existing home and how you plan to use the space, planned for ADU construction in Millbrae.
New construction units built in the back or side yard of a single-family home, also called backyard cottages or granny flats.
Convert an existing garage into a stylish and practical living unit.
Turn a basement into an in-law unit or secondary suite with its own living space.
An in-law suite attached to the existing home, with its own entrance.
A smaller unit created within the existing home for family members or guests.
Plans, 3D models and permit submittals prepared by our team.
In Millbrae, ADU permits are submitted to the Building Division, and the City also reviews and pre-approves ADU plans. ADUs under 750 square feet are exempt from Development Impact Fees. ADUs that add more than 500 square feet also require school developer fees, paid to two school districts before the permit is issued.
Residential building permits in Millbrae are handled by City of Millbrae Building Division, 621 Magnolia Avenue, Millbrae, CA 94030. Phone: 650-259-2330.
The permitting agency makes the final call on what your scope needs. We confirm the requirements for your project, secure the permits before construction starts and coordinate each inspection through to the final sign-off.
Four clear stages for ADU construction in Millbrae, so you always know what happens next.
Call us or send the form to schedule a free, no-obligation consultation. We review your budget and brainstorm ideas.
Our in-house designers create plans and 3D models for your approval.
Once you approve the design, we secure the necessary permits and confirm the schedule with you.
Construction begins once the permit is issued. We pass the final inspection, and your project is complete.
Real homes built and remodeled by Preferred Builders in San Jose, Walnut Creek and San Carlos.

A home addition plus a full remodel, including the kitchen, bathrooms, painting and flooring.
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A 3,000-square-foot house built from the ground up.
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Kitchen, bathrooms, new flooring and a basement converted into living space.
View the projectDon’t see your question? Call (669) 588-3929 and talk to our team.
An ADU, or accessory dwelling unit, is a secondary housing unit on a single-family residential lot. It can provide rental income or serve as a guest house or home office.
It depends on your lot size, your existing structures and your goals. We review your property and compare detached, attached, garage and basement options.
Yes. ADUs need building permits and must meet the City's ADU standards. We prepare the plans and handle the submittals.
Yes. Our in-house designers create the plan, and we use 3D modeling so you can see the ADU before construction begins.
City of Millbrae Building Division, 621 Magnolia Avenue, Millbrae, CA 94030. We confirm the requirements for your scope and secure the permit for your ADU construction in Millbrae.
Yes. We handle ADU construction in Millbrae and across San Mateo County from our office in Milpitas. Call (669) 588-3929 to arrange a free, no-obligation consultation.
Our team also handles ADU construction in neighboring cities.
Tell us what isn’t working today and what you want to change. Share your address, your timing and any photos you have.
(669) 588-3929Whether you have a detailed vision or simply know something needs to change, start with a free, no-obligation consultation.
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