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Top 6 Tips to Reduce Your ADU Costs

Co-Authored by Scott Johnson, ADU Expert @ Napa Sonoma ADU Center & Founder, Pocket Housing LLC & Renée Schomp, Director, Napa Sonoma ADU Center

Accessory dwelling units are big projects, but they are well worth it.

When you build an ADU you’re building a house — and while it may have less square feet than the average house, it still contains all of the same features and must be up to the same building standards as a regular house: Kitchen, bathroom, foundation, electrical, plumbing, insulation, framing — you name it. 

As long as you set your expectations accordingly, you’ll be well-prepared for a successful ADU build.

Side note: If you’re converting already-finished space such as part of your existing home or other existing space that meets the higher building code requirements for a living space, this may not apply to the same degree for your ADU project!

But even though building an ADU is a big project, you can make choices that help keep costs down from the get-go. Plus, you can think through your budget and the return on your investment using our ADU Calculator!

  1. Go all electric: Some jurisdictions are requiring all electric builds, but even if they aren’t, you can save money by eliminating the need for running a gas line to the new unit.

  2. Submeter the utilities: For most projects you don’t need to make new connections to the water and sewer, you can simply T off the main house. This can save thousands of dollars in work and connection fees. 

  3. “One wet wall” design: Work with your designer to keep the plumbing for the kitchen and bath within one shared wall. This can simplify the plumbing dramatically, thus keeping costs down.

  4. Keep the design simple: A good designer can work within your budget — and keeping the design as simple as possible will keep costs down. We’ve seen projects where the initial design was overly complicated, and the roof alone was $40,000. Simplifying the design ended up saving tens of thousands of dollars. Choose simpler finishes. For example, going with a tile bathroom or kitchen backsplash can add thousands of dollars to the cost.

  5. Bring your builder on early in the process: The professional building your ADU will be the person most likely to have a realistic understanding of the likely cost of your proposed ADU design. So bring them in early, ideally to connect with your designer and ensure that the plans being drawn up are actually likely to meet your budget. 

  6. Work with an experienced professional team: Ideally one that understands your local ADU rules and the processes at your jurisdiction’s Planning & Building Department.

Want customized help at “Step Zero” thinking through cost drivers specific to your ADU project? Sign up for an ADU Feasibility Consult from our nonprofit today!

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