Permit Fee Estimator

How Much Will ADU Permits Cost?

Get an itemized estimate of permit fees for your ADU project. See building, plan check, electrical, plumbing, and impact fees by state.

ADU Permit Fee Calculator

Estimate permit costs for your ADU project with itemized fee breakdowns, timeline estimates, and required document checklists.

Project Details

800 sqft
200 sqft1,200 sqft
$212,000

Auto-calculated from ADU type and size

Tip: Garage conversions and JADUs typically have lower permit fees due to reduced scope of work. Check with your local building department for exact fees.

Estimated Permit Fees

800 sqft Detached ADU · California

Total Estimated Permit Fees
$23,992
State-Level Estimate

Fee Breakdown

Building Permit
$8,480
Plan Check (65%)
$5,512
Electrical Permit
$560
Plumbing Permit
$480
Mechanical Permit
$400
Impact / Utility Fees
$5,760
School Fees(California only)
$2,800
Total$23,992

Permit Timeline

Typical permit approval: 6–12 weeks (California)

Required Documents

Site plan
Floor plan
Structural calculations
Energy compliance report
Foundation plan
Electrical plan
Plumbing plan
See Total Project CostFinancing Options

ADU Permit Fees by State (2026)

Permit fees are one of the most misunderstood costs in ADU construction. Many homeowners budget for materials and labor but are surprised by permit expenses that can add $2,000 to $15,000 or more to the total project cost. Understanding these fees upfront helps you budget accurately and avoid costly surprises during construction.

ADU permit fees vary dramatically by location. High-cost states like California and New York charge significantly more due to stricter building codes, environmental reviews, and impact fees. In contrast, states like Texas and Arizona have streamlined permitting processes with lower fees. City-level variations can be even more significant — permit fees in San Francisco may be double those in Sacramento for the same size ADU.

What's Included in ADU Permit Fees

  • Building permit: The primary permit covering structural work, typically the largest fee ($2,500-$8,000+)
  • Plan check fee: Review of your construction drawings, usually 50-65% of the building permit fee
  • Trade permits: Separate permits for electrical, plumbing, and mechanical (HVAC) work ($200-$500 each)
  • Impact fees: Fees for increased demand on public infrastructure like roads, water, and sewer ($0-$5,000+)
  • School fees: Required in some states (notably California) to fund school district capacity ($2-$4 per sqft)

How to Reduce ADU Permit Costs

Several strategies can help reduce your ADU permit expenses. Many jurisdictions waive impact fees for ADUs under 750 square feet. Garage conversions and JADUs typically have lower permit fees because the existing structure reduces the scope of work. Some cities offer fee waivers for ADUs committed to affordable rents, and pre-approved ADU plans can reduce plan check fees and processing time.

Pro Tip: Many ADU-friendly cities now offer pre-approved ADU plans that can save $5,000-$15,000 in design costs and reduce permit processing time by 2-4 weeks. Check with your local planning department for pre-approved plan options.

Disclaimer: Permit fee estimates are based on state-level averages and may not reflect exact fees in your jurisdiction. Contact your local building department for precise fee schedules. Fees change periodically and may differ from the estimates shown here.

Cost Estimator → Financing Calculator → Break-Even Calculator → Rental Income Calculator →

Frequently Asked Questions

How much do ADU permits cost?
ADU permit fees typically range from $2,000 to $15,000 depending on your location, ADU type, and size. California tends to have the highest permit costs, while states like Texas and Arizona are more affordable. Fees include building permits, plan check, electrical, plumbing, and mechanical permits, plus potential impact and school fees.
What permits do I need to build an ADU?
Building an ADU typically requires a building permit, plan check review, electrical permit, plumbing permit, and mechanical (HVAC) permit. Some jurisdictions also require grading permits, sewer/water connection fees, school impact fees, and utility upgrade permits. You'll need to submit site plans, floor plans, structural calculations, and energy compliance reports.
How long does it take to get an ADU permit?
ADU permit approval typically takes 4-12 weeks depending on your jurisdiction. California cities average 6-12 weeks, while states like Texas and Arizona can process permits in 3-6 weeks. Many California cities now have streamlined ADU processes with 60-day approval deadlines per state law.
Can I get ADU permit fees waived?
Some cities offer ADU permit fee waivers or reductions, especially for affordable housing units. California limits impact fees for ADUs under 750 sqft. Cities like Los Angeles, San Jose, and Portland have offered fee waivers for ADUs committed to affordable rents. Check with your local planning department for current incentive programs.
Do garage conversions need permits?
Yes, garage conversions require permits in virtually all jurisdictions. However, permit fees for garage conversions are typically 30-50% lower than new detached ADUs because the existing structure reduces the scope of work. You'll still need building, electrical, plumbing, and mechanical permits, but some inspections may be simplified.