Coastal ADU Construction is a Bay Area design/build contractor specializing in accessory dwelling units. They handle detached ADUs, garage conversions, in-law suites, and granny flats, managing both design and construction while navigating local zoning regulations.

Coastal ADU Construction, San Francisco, CA

About Coastal ADU Construction

About Coastal ADU Construction

Coastal ADU Construction is a local accessory dwelling unit general contractor serving Bay Area homeowners. As more property owners look to make better use of their land, ADUs have become an increasingly popular option — whether for accommodating guests, housing family members, or generating rental income.

An accessory dwelling unit — also referred to as a backyard cottage, in-law apartment, or granny flat — is a separate residential living space built on the same property as a single-family home. These units offer homeowners a practical way to leverage available space while adding long-term value to their property.

Types of ADUs Coastal ADU Construction Works With

Not every property is the same, and the right type of ADU depends on the existing configuration of the land and the homeowner's intended use. Coastal ADU Construction works across several ADU types:

  1. New construction of a freestanding or detached ADU
  2. Conversion or expansion of an existing secondary structure, such as a garage conversion, into an ADU
  3. Conversion of a space within the main home — such as a basement or attic — into an ADU
  4. Addition of an attached ADU to the main home

Each of these approaches comes with its own set of considerations, from structural requirements to zoning regulations. Coastal ADU Construction has experience across all of these project types, helping homeowners identify which solution fits their property and goals.

Design, Planning, and Construction

While building a backyard cottage or in-law suite may appear straightforward on the surface, local regulations in the Bay Area can be complex. Careful planning and efficient design are important factors in ensuring that a compact space remains comfortable and livable.

Coastal ADU Construction operates as a design/build ADU contractor, meaning they handle both the design and construction phases of a project. Their team has the knowledge to help homeowners navigate local requirements, explore available options, and make informed decisions throughout the process.

Whether a homeowner is considering a Casita, a converted garage, or a newly built detached ADU, Coastal ADU Construction works to match the project to the property, the budget, and the intended purpose. They offer free estimates for those looking to get started.

Services

Coastal ADU Construction performs the following services

  • Architecture & Design
  • Construction

Coastal ADU Construction Reviews

Glenn S. Gordon

2026-01-15
"James was outstanding from start to finish. I recently completed building a house, so Ive had plenty of experience dealing with contractors, and James stood out immediately. He took the time to walk us through every step of the ADU process, answered every question with real clarity, and was consistently transparent about costs, timelines, and feasibility. Out of the three contractors I spoke with, he was easily the most knowledgeable and the most straightforward. Even though we ultimately decided not to move forward with the project for our own cost and ROI reasons, the pre-construction experience with James was genuinely excellent. He never pushed, never oversold, and made sure we understood exactly what we would be getting into. If we ever revisit the idea, he will be the first person we call. Highly recommended for anyone wanting honest guidance, detailed expertise, and a contractor who actually listens."

Trisa Knight

2026-01-06
"It took many many years to decide to move forward with an addition project for our home. We decided going with an ADU was the best plan. I researched and talked to several companies. When I met James the first time I knew right away that they were going to be the best company for us. We decided on a 2 bedroom, 2 bath with laundry closet and a full kitchen. Everyone that visits says it feels so big! We have zero regrets on hiring West Coast Construction Pro Build! They worked with us on the design plans, taking in all my changes and suggestions without question. John was our Project Manager. He was the BEST! He is very responsive to text and calls. He was so helpful every step of the way and let us know everything happening step by step! Every single contractor involved in the project was hard working, kind and respectful! I was sad when the day came to completely turn the place over to us as that meant not seeing John regularly, yes he was that wonderful! Our ADU turned out better than expected and I would 1000 percent recommend this company!"

Brian Bollinger

2025-12-27
"We recently completed our ADU RV Garage with West Coast Construction Pro, and the experience was exceptional from start to finish. We found their pricing to be more competitive than other local firms without sacrificing quality. From Design to Execution to any Change Orders, the numbers always made sense. What really stood out was their honesty and transparency. We never felt like we needed more granularity; everything was laid out clearly from day one. Throughout the build, their communication was constant and quickwe were never left wondering about the status of the project. Construction always comes with a few unexpected hurdles, but we were impressed by their collaborative approach to challenges. Instead of just telling us "this is how it needs to be done," they worked with us to find solutions that aligned better with our aesthetic and functional needs. If you want a builder you can actually trust, I highly recommend them!"

Jeffrey Lu

2025-11-23
"We recently completed an ADU project with James, Johny, and the team. Start to finish took roughly 10 months design, engineering, permitting, construction, finishes, city inspections, with around 4 months of active construction. I enjoyed working with the West Coast team and would not hesitate to look to them again. The team is easy to work with, communicative, flexible, and they provided a competitive bid. I scouted out several ADU builders at the beginning of the project. James stood out with his level of care. Several other builders I sought quotes from felt impersonal and commercial, while James cared about making sure the project would fit my needs and preferences. James was willing to work through a number of requests that many other builders didn't want to explore, including advanced framing, unusual flooring, a custom floorplan, and complete discretion over the materials and finishes used. It felt like we were building a project together, and not just purchasing a mostly pre-arranged service. Much appreciation and thanks to the entire West Coast team!"

Giuliana Esparta

2025-09-05
"We recently engaged West Coast to build a 652 ft2 ADU as an addition to our rental property, and the entire experience was exceptional. From the initial brainstorming and design phase through planning and execution, James, John and their team demonstrated professionalism, expertise and dedication. I first learned about WC through a Facebook advertisement and, admittedly, approached the process with some skepticism. However, the company quickly exceeded my expectations. Their proposal and charges were clearly defined in the contract, and they offered flexibility when I preferred to source certain materials on my own. Communication throughout the project was outstanding timely, transparent, and consistent. Even more impressive, the construction was completed in just 3.5 months, from breaking ground to final delivery. James and John were consistently punctual, responsible, and a pleasure to work with. Thanks to WCs commitment and performance, our vision became a reality. I would not hesitate to recommend them to anyone seeking a reliable and trustworthy partner for their construction projects."

Specifics

Opening hours

Monday 8:00AM - 7:00PM
Tuesday 8:00AM - 7:00PM
Wednesday 8:00AM - 7:00PM
Thursday 8:00AM - 7:00PM
Friday 8:00AM - 7:00PM
Saturday 8:00AM - 7:00PM
Sunday -

Location

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