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ADU Cost Guide

ADU Permit Fees: What You'll Actually Pay in 2026

Q: How much does an ADU permit cost?

ADU permit costs range from $2,000 to $20,000+ depending on the city, ADU size, and fee categories. The national average is $5,000–$12,000. California cities average $4,000–$10,000 due to state-mandated fee waivers for ADUs under 750 sq ft. Major cities like Los Angeles, San Francisco, and San Jose tend to be at the higher end.

Q: What fees are included in an ADU permit?

ADU permit fees typically include: plan check fees ($500–$3,000), building permit fees ($1,000–$5,000), school district fees ($2–$5 per sq ft), utility connection fees ($2,000–$10,000), impact fees ($0 for ADUs under 750 sq ft in California), and sometimes planning review fees ($200–$1,500). Each jurisdiction bundles these differently.

Q: Are ADU impact fees waived in California?

Yes, partially. California law waives impact fees entirely for ADUs under 750 sq ft. For larger ADUs, impact fees are calculated proportionally based on the ADU's square footage relative to the primary dwelling. This can save $5,000–$30,000 depending on the city.

Q: How do I reduce ADU permit costs?

Use pre-approved ADU plans (saves $5K–$15K in design review), build under 750 sq ft to qualify for California's impact fee waiver, apply for local fee waiver programs (Portland, San Jose, and others offer them), and connect to existing utilities rather than running new service lines.

Q: Do ADU permit fees differ from regular building permits?

Yes. Many states and cities have created reduced ADU-specific fee structures. California requires that ADU permit fees be proportional to the unit's size and impact — they cannot match fees for a full single-family home. Some cities have created flat-fee ADU permits that are significantly cheaper.

Q: Are there hidden fees when permitting an ADU?

Common 'hidden' fees include: sewer capacity charges ($3,000–$8,000), water meter installation ($2,000–$5,000 for a separate meter), fire sprinkler system review ($500–$1,500), energy compliance review ($200–$800), and address assignment fees ($100–$300). Ask your local building department for a complete fee schedule before budgeting.

Plan check, building permits, impact fees, school fees, and utility connections — broken down by city with California fee waivers explained.

Quick Answer

ADU permit fees range from $3,000 to $20,000+ depending on your city and ADU size. The national average is $5,000–$12,000. California waives impact fees for ADUs under 750 sq ft, saving $5,000–$30,000. The biggest cost drivers are utility connections and impact fees — not the building permit itself.

Updated April 2026

What's Included in ADU Permit Fees?

"ADU permit fees" is actually a bundle of 5–8 separate fees charged by different departments and agencies. Understanding each component helps you budget accurately and identify savings opportunities.

Plan Check Fee

$500–$3,500

The city's review of your ADU plans for code compliance. Calculated as a percentage (65–85%) of the building permit fee. Pre-approved plans can reduce or eliminate this fee.

Building Permit Fee

$1,000–$5,500

The core permit to construct your ADU. Typically calculated based on project valuation using ICC building valuation data. This is the fee most people think of when they hear 'permit cost.'

Impact Fees / Development Fees

$0–$30,000+

Fees for the ADU's impact on public infrastructure (parks, roads, fire, police). California waives these for ADUs < 750 sq ft. This is the single largest variable in ADU permit costs.

School District Fees

$2–$5 per sq ft

California-specific. Levied by local school districts on new residential construction. A 600 sq ft ADU might owe $1,200–$3,000. Some districts have negotiated reduced ADU rates.

Utility Connection Fees

$2,000–$10,000+

Fees to connect the ADU to water, sewer, electric, and gas. Shared connections with the main house are cheaper. New separate meters and service lines cost significantly more.

Planning / Zoning Review

$200–$1,500

Some cities charge a separate planning review fee before the building permit phase. Ministerial (by-right) ADU review should not include discretionary planning fees under California law.

Fire Sprinkler Review

$500–$1,500

If your ADU requires fire sprinklers (common in ADUs > 500 sq ft or with specific setback conditions), the fire department charges a separate plan review fee.

Other / Misc

$200–$1,000

Address assignment ($100–$300), energy compliance review ($200–$800), grading permit (if applicable), and administrative processing fees.

City-by-City ADU Permit Fee Comparison

Here's a detailed breakdown of ADU permit fees across 18 cities. Search, filter, or sort the table to find your city. Click any city name to see its full cost guide.

Showing 18 of 18 cities

City▲	Plan Check	Building Permit	Impact Fees	School Fees	Utilities	Total Est.
Austin, TX	$600–$1,500	$1,000–$3,000	$3,000–$10,000	N/A	$2,000–$5,000	$6,600–$14,500
Chula Vista, CA	$800–$2,000	$1,200–$3,000	Waived (< 750 sf)	$2–$4/sf	$2,000–$6,000	$4,000–$11,000
Coronado, CA	$1,200–$3,000	$2,000–$5,000	Waived (< 750 sf)	$3–$4/sf	$3,000–$8,000	$6,200–$16,000
Denver, CO	$800–$2,000	$1,500–$3,500	$2,000–$6,000	N/A	$2,000–$5,000	$6,300–$11,500
El Cajon, CA	$800–$2,000	$1,000–$3,000	Waived (< 750 sf)	$2–$4/sf	$2,000–$5,500	$3,800–$10,500
Imperial Beach, CA	$600–$1,500	$1,000–$2,500	Waived (< 750 sf)	$2–$3/sf	$2,000–$5,000	$3,600–$9,000
La Jolla, CA	$1,000–$2,500	$1,500–$4,000	Waived (< 750 sf)	$2–$4/sf	$2,500–$7,000	$5,000–$13,500
Los Angeles, CA	$1,500–$3,500	$2,000–$5,000	Waived (< 750 sf)	$3–$4/sf	$3,000–$8,000	$6,500–$16,500
Miami, FL	$800–$2,000	$1,200–$3,500	$3,000–$12,000	N/A	$2,500–$6,000	$7,500–$18,500
Portland, OR	$800–$2,000	$1,500–$3,500	$0–$5,000	N/A	$2,000–$6,000	$4,300–$11,500
Raleigh, NC	$500–$1,200	$800–$2,500	$2,000–$8,000	N/A	$2,000–$5,000	$5,300–$11,700
Sacramento, CA	$800–$2,000	$1,200–$3,500	Waived (< 750 sf)	$2–$4/sf	$2,000–$5,000	$4,000–$10,500
San Diego, CA	$1,000–$2,500	$1,500–$4,000	Waived (< 750 sf)	$2–$4/sf	$2,500–$7,000	$5,000–$13,500
San Francisco, CA	$2,500–$5,000	$3,000–$8,000	Waived (< 750 sf)	$4–$5/sf	$5,000–$12,000	$10,500–$25,000
San Jose, CA	$1,200–$3,000	$2,000–$5,500	Waived (< 750 sf)	$3–$5/sf	$3,000–$9,000	$6,200–$17,500
Scottsdale, AZ	$600–$1,500	$1,000–$2,500	$1,000–$4,000	N/A	$2,000–$5,000	$5,000–$10,000
Seattle, WA	$1,000–$2,500	$2,000–$4,500	$0–$8,000	N/A	$2,500–$7,000	$5,500–$14,000
Spring Valley, CA	$600–$1,500	$1,000–$2,500	Waived (< 750 sf)	$2–$3/sf	$2,000–$5,000	$3,600–$9,000

Estimates for a 600 sq ft detached ADU. Actual fees vary by project specifics. Updated April 2026.

California's ADU Fee Waivers

California has the most aggressive ADU fee reduction laws in the country. Here's what's waived and what still applies:

Fee Type	ADU < 750 sq ft	ADU ≥ 750 sq ft
Impact / Development Fees	Fully waived	Proportional (based on ADU size ÷ primary home size)
Utility Connection Fees	Waived for shared connections	May require new connections (full fees apply)
School District Fees	Still applies ($2–$5/sf)	Still applies ($2–$5/sf)
Building Permit Fees	Reduced (ADU-specific schedule)	Reduced (ADU-specific schedule)
Plan Check Fees	Reduced or waived with pre-approved plans	Standard rates apply
Planning Review Fees	Ministerial — should be $0 or minimal	Ministerial — should be $0 or minimal

Important: Cities Can Still Charge Other Fees

While California waives impact fees for small ADUs, cities can still charge building permit fees, plan check fees, school fees, and utility connection fees. Some cities also charge "capacity" fees that function similarly to impact fees but under different names. Always request a complete fee estimate from your building department before budgeting.

Factor Permit Fees Into Your ADU Budget

Our cost estimator includes permit fee estimates for your specific city and ADU size.

Estimate Your Total Cost

How to Reduce ADU Permit Costs

Use Pre-Approved Plans

California's AB 1332 requires cities to offer pre-approved ADU plans. These skip or reduce plan check fees ($500–$3,000 saved) and speed permitting from months to weeks. San Jose, LA, and San Diego all offer them.

Build Under 750 sq ft

California waives all impact fees for ADUs under 750 sq ft. In cities with high impact fees (LA, San Francisco), this alone can save $10,000–$30,000. A 749 sq ft ADU is one of the best cost-optimized sizes.

Share Utility Connections

Connecting to the main house's existing water, sewer, and electrical service avoids new service line fees. California law prohibits cities from requiring separate utility connections for ADUs under 750 sq ft.

Apply for Fee Waiver Programs

Portland's SDC Waiver saves up to $20,000. San Jose offers fee deferrals. Many cities have income-qualified fee reduction programs. Always ask your building department about available waivers.

Build a JADU Instead

JADUs (under 500 sq ft, within the existing home) have the lowest permit fees — often $1,000–$4,000 total — because they require minimal new utility connections and have reduced plan check requirements.

Get a Full Fee Estimate First

Before committing to a design, request a written fee estimate from your building department. This prevents budget surprises and lets you optimize the ADU size and configuration to minimize fees.

Permit Fee Timeline: When Are Fees Due?

ADU permit fees aren't paid all at once. Here's when each fee is typically collected:

Plan Submittal (15–25% of total fees)

Fees: Plan check fee, planning review fee

Due when you submit your ADU plans for review

Permit Issuance (40–60% of total fees)

Fees: Building permit fee, impact fees, school fees

Due when the city issues your building permit

Construction (5–10% of total fees)

Fees: Inspection fees (often included in permit), fire sprinkler review

Paid as inspections are scheduled

Final / Utility (20–35% of total fees)

Fees: Utility connection fees, meter installation, address assignment

Due before final inspection or at utility connection

Frequently Asked Questions

How much does an ADU permit cost?