Los Angeles County · California
Diamond Bar ADU Fees in 2026
We have not published verified fee figures for Diamond Bar yet. Our researchers verify every line item against its official source document before publishing — no fee modeled, no fee guessed.
Every figure links to its official source document. Last verified 20 Oct 2026. Fees are re-verified on a rolling schedule (next full pass Dec 2026). Official fee schedule ↗ How we price →
Verification in progress
Our researchers are working through Diamond Bar's official fee schedules now. We publish a line item only after we have read the source document — no fee modeled, no fee guessed. Check back soon, or run the calculator for the statewide baseline in the meantime.
What changes on January 1, 2027
Two state laws rewrite parts of this table. SB 1117 (Chapter 809) re-bases covered impact fees for up to two ADUs on only the square footage above 750 — at 800 sq ft, most impact-fee lines shrink to a 50 sq ft basis. School developer fees and water/sewer connection or capacity charges are not covered and do not change. AB 956 (Chapter 791) makes two detached ADUs per single-family lot a ministerial approval. Details: SB 1117 and the 750 sq ft cliff · AB 956: two ADUs on one lot
Common questions
Are impact fees waived for ADUs under 750 sq ft in Diamond Bar?
Yes. California law (Gov. Code §66311.5) bars local agencies from charging impact fees on ADUs of 750 square feet or less. That applies in Diamond Bar the same as everywhere else in California.
Where do these Diamond Bar ADU fee numbers come from?
Every line item links to the official source document — the city or county fee schedule, the school district's developer-fee resolution, or the utility district's charges — with the date we last verified it. We publish no fee modeled, no fee guessed.
Embed this fee card
Bloggers, realtors, journalists: drop this city's live fee card into your page. Numbers stay current; every figure links back to its source.
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