09/29/2026
California just made larger ADUs a little more practical.
SB 1117 has been signed into law, changing how certain impact fees are calculated for ADUs larger than 750 sq. ft.
For up to two ADUs on a lot:
→ ADUs 750 sq. ft. or smaller remain exempt from impact fees.
→ For ADUs larger than 750 sq. ft., qualifying impact fees are calculated only on the square footage above 750 sq. ft.
Example: Build a 1,000 sq. ft. ADU, and the impact-fee calculation applies to the additional 250 sq. ft. — not the entire 1,000 sq. ft.
For property owners considering a larger ADU, that can change the feasibility conversation.
Before deciding how much to build, understand the property, the development rules, the costs and the capital structure.
PROPERTY. CAPITAL. EX*****ON.
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