ADU Cost Planning
Build a budget around the complete project.
A useful ADU budget includes the building and the work needed to make it possible. Compare proposals using the same plans, assumptions and finish selections.
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Organize the budget
Separate design and engineering, agency charges, site work, utility connections, construction, finishes and contingency. Identify owner-paid items and allowances. Ask whether demolition, hauling, landscaping repair and electrical upgrades are included.
Compare conversion and new construction
Reusing a garage may reduce some work, but foundation repairs, structural changes and utility routes can offset the difference. Review the actual building before assuming a conversion will be cheaper.
Turn a range into a proposal
Early numbers help compare directions. A detailed proposal needs a defined scope and current site information. Record exclusions, allowances, payment stages and how changes will be approved. Use the planning calculator with your own estimate inputs, then request a property-specific review.
Start with the California ADU Handbook.
The March 2026 edition covers statewide ADU and JADU planning topics. Download the 55-page PDF free, with no signup required.
Bring the plan back to your property.
Virtual Estimates Available. Share your address and goals to discuss the next step.
Request a feasibility reviewBrowse all ADU resources