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Modesto ADU guides
Short answer first, then the detail and the cases where it depends. Each rule and figure has a date and a source.
Updated October 2026
01
How much does an ADU cost in Modesto?
The nearest published 2026 price ranges, the costs that swing a budget, and the fees the state removes.Read the guide 02Are there free ADU plans in Modesto?
Yes. The county-and-cities plan set, its sizes, and what a homeowner still submits.Read the guide 03How much rent can an ADU get in Modesto?
HUD's 2026 benchmarks for the Modesto metro and the factors that move ADU rent.Read the guide 04How big can an ADU be in Modesto?
The state floors and caps on size and height, and how Modesto's ordinance was brought in line.Read the guide 05Can I get a loan to build an ADU in Modesto?
The city's revolving loan fund with Valley First Credit Union, and its eligibility rules.Read the guide 06Can I legalize an unpermitted ADU in Modesto?
Often, if it was built before 2020. What state law protects and what it does not.Read the guideFind out what your lot allows
Guides explain the rules in general. Share your address for an answer about your parcel.