CA ADU Costs
California ADU Cost Breakdowns
Where every ADU dollar actually goes.
Line-item cost breakdowns for real California builds. Six phases, every fee, every city — so you can check a contractor's number before you sign.
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- Oct 12, 2026Fontana ADU Fees 2026: $20,563 in Impact Fees — and a 738 Sq Ft LoopholeFontana charges $20,563 per new single-family home in development impact fees — among the heaviest in our series — but its own free 738 sq ft ADU plan slips under the 750 sq ft cliff and pays $0. An 800 sq ft detached ADU priced phase by phase, with the city's flat $3,195 permit and the state's maximum $5.38 school fee.$319,000*
- Oct 12, 2026Laguna Beach ADU Cost 2026: $314,000, No Coastal Premium800 sq ft ADU in Laguna Beach: ~$314,000. No impact fees, $215/100 sq ft sewer, $2.05 school fee.~$314,000
- Oct 11, 2026Santa Barbara ADU Cost 2026: $327,000, Priciest Permit800 sq ft detached ADU in Santa Barbara: ~$327,000 total. Permit + plan check ~$22,566 — the series high. No city impact fees. Phase-by-phase breakdown.~$327,000
- Oct 11, 2026On Jan 1, 2027, California Kills the 750 Sq Ft Cliff — Here's What You'd SaveSB 1117, signed Sept 29, 2026, rewrites the ADU impact-fee rule: from Jan 1, 2027, cities may charge fees only on square footage above 750 — not the whole unit. City-by-city savings table: Palo Alto ~$8,000–$20,000 → ~$500–$1,250; Anaheim ~$10,411 → a fraction. What changes, what doesn't, and the December-vs-January permit question.
Videos
Short · Oct 10, 2026
The 750 sq ft Cliff Ends Jan 1, 2027
SB 1117 limits impact fees to the square footage above 750.
Long-form · Oct 9, 2026
5 Numbers Missing From Every ADU Quote
The four-bucket method for reading contractor bids.
2026 ADU benchmark sheet
Quarterly cost ranges for every build on this site, in one CSV. Free download, no email needed.