Compare · checked Oct 18, 2026

Palo Alto vs Mountain View ADU fees: Palo Alto is about $15,555 lower for a 1,000 sq ft ADU

Modeled from each place’s official fee schedules for a detached ADU next to a 2,000 sq ft main home (example assumption), law in force today. Ranges count fees that always apply (low) and fees that may apply (high). Both places are fully modeled, so the totals compare like for like.

Modeled fee totals by ADU size

	Palo Alto	Mountain View	Lower
499 sq ft	$2,000–$8,000	$7,240–$43,032	Palo Alto by $35,032
750 sq ft	$2,000–$12,035	$7,240–$47,067	Palo Alto by $35,032
1,000 sq ft	$24,613–$35,993	$8,997–$51,548	Palo Alto by $15,555
1,200 sq ft	$29,136–$41,592	$9,348–$53,252	Palo Alto by $11,660

Where the money goes at 1,000 sq ft

	Palo Alto	Mountain View
Planning & zoning	–	$240–$720
Building permit & plan check	$2,000–$8,000	$7,000–$25,000
Impact fees	$22,613	$1,757–$3,137
School district fee	$0–$5,380	$0–$5,380
Utility connections	–	$0–$17,312
Impact fees under SB 1117 (from 2027)	$5,653	$784
ADU permits issued, 2025	136	86

Line-by-line figures with the quoted source text: Palo Alto · Mountain View. Permits: HCD Annual Progress Report data.

Rules side by side

	Palo Alto	Mountain View
Maximum size	800 sq ft detached on any eligible lot. Larger: 900 sq ft (1 bedroom) or 1,000 sq ft (2+ bedrooms) under added City standards.	Single-family lots: 850 sq ft (studio or 1 bedroom) or 1,000 sq ft (2+ bedrooms); an attached ADU is capped at 50% of the main home. Multifamily lots: 1,200 sq ft detached.
Height	16 ft (18 ft within ½ mile of transit, +2 ft to match the roof pitch). Larger ADUs under City standards: up to 25 ft or the zone limit, 2 stories.	28 ft for a 1- or 2-story ADU (a basement counts as a story).
Setbacks	4 ft rear and side; front per the zoning district.	4 ft side and rear; front per the zoning district.
Parking	None for new second units (replacement uncovered parking when built with a new home that has no covered parking).	None for a studio; one space for 1+ bedrooms, with exceptions (City Code 36.12.95). None on multifamily lots.
Owner occupancy	Not required for an ADU. For a JADU, the owner must live in the main home or the JADU.	Not required for an ADU. For a JADU, an owner must live in the house or the JADU.
Pre-approved plans	State law: every city must run a program to pre-approve ADU plans (Gov. Code 65852.27).	State law: every city must run a program to pre-approve ADU plans (Gov. Code 65852.27).
Junior ADU (JADU)	Not captured yet.	Up to 500 sq ft, entirely within the walls of the house; a deed restriction is recorded.

Grey text is the state floor where we haven’t captured the local rule yet.

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FAQ

Palo Alto vs Mountain View: questions

Are ADU fees higher in Palo Alto or Mountain View?

For a detached 1,000 sq ft ADU with a 2,000 sq ft main home, our model of the official schedules gives Palo Alto $24,613–$35,993 and Mountain View $8,997–$51,548.

Which charges more impact fees on an ADU, Palo Alto or Mountain View?

At 1,000 sq ft: Palo Alto $22,613, Mountain View $3,137 (proportional to a 2,000 sq ft house). Neither can charge impact fees at 750 sq ft or less. From 2027, SB 1117 limits them to the area over 750 sq ft: $5,653 and $784 in our model.

What does a 750 sq ft ADU cost in fees in each?

Palo Alto: $2,000–$12,035. Mountain View: $7,240–$47,067. At 750 sq ft or less, state law bars impact fees in both.

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