ADU Permitting Timeline by State: How Long Does It Really Take?

One of the most common shocks for [homeowners](/blog/home-insurance-savings) pursuing an ADU ([Accessory Dwelling Unit](/blog/multigenerational-housing-guide)) project is how long the permitting process takes. Contractors quote 3–6 months to build your unit. Nobody tells you it could take another 3–12 months just to get your permits.

Understanding permitting timelines before you start planning—and budgeting—can save you enormous frustration and help you line up financing at the right moment.

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Why Permitting Timelines Vary So Dramatically

ADU permitting isn't controlled at the federal or state level (except in [California](/blog/california-heloc-guide), which has enacted sweeping state preemptions). It's controlled by local jurisdictions—cities, counties, and special planning districts—each with their own:

• Staffing levels for plan review
• Zoning complexity and overlay districts
• ADU ordinance age (new ordinances mean untrained staff)
• Public comment requirements
• Historic preservation review requirements
• Flood zone and environmental review triggers

A city like Austin, TX has dedicated ADU staff and streamlined review. A small rural county in the Midwest may have never processed an ADU permit before and lacks the capacity.

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California: The National ADU Leader

California has done more than any other state to reduce ADU permitting barriers. Key laws:

• AB 68 (2019): Eliminated owner-occupancy requirements, reduced setbacks, removed parking replacement mandates
• SB 13 (2019): Capped ADU permit fees for smaller units
• AB 3182 (2020): Required HOAs to allow ADUs in most circumstances
• AB 345 (2021) / SB 897 (2022): Further streamlined provisions for multi-family ADUs, reduced setbacks for ADUs near public transit

California-mandated permit timeline: Cities must act on ADU permit applications within 60 days. If they don't, the permit is deemed approved. This is a hard statutory deadline—many cities struggle to meet it, but applicants can enforce it.

Real-world timelines by California city:

California ADU Regulations: Complete Guide → California ADU Regulations 2026

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Oregon

Oregon passed HB 2001 (2019), allowing duplexes and ADUs in most residential zones statewide. Portland has been an ADU leader since 2010.

Permit timelines:

Portland's Bureau of Development Services has ADU-specific reviewers and a streamlined process. Small cities in Oregon may take longer.

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[Washington](/blog/washington-heloc-guide) State

Washington allows ADUs statewide through the Growth Management Act, but implementation varies by jurisdiction.

Seattle's DADU (Detached ADU) program is mature and well-documented. The city offers pre-application conferences and standard plan libraries to speed up review.

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Texas

Texas has no statewide ADU law—ordinances are entirely local. Results vary dramatically.

Texas ADU Regulations → Texas ADU Regulations Guide

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New York

New York State passed a law in 2022 allowing ADUs in single-family zones statewide—but implementation is uneven. NYC has its own complex code.

NYC ADU Regulations → NYC ADU Regulations Guide

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Florida

Florida allows ADUs statewide under HB 1339 (2023), which requires cities to allow ADUs as a matter of right in most residential zones.

Florida's ADU law is relatively new, and many cities are still updating their ordinances to comply. Expect some friction in smaller jurisdictions.

Florida ADU Laws → Florida ADU Laws Guide

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Colorado

Colorado passed SB 23-213 (2023), requiring cities over 1,000 people to allow ADUs in most residential zones.

Denver's ADU-specific reviewers and online portal have made it one of the more efficient cities in the Mountain West.

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States With Limited ADU Access (Slower Permitting)

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How to Speed Up Your ADU Permit

Regardless of your jurisdiction, these strategies reduce wait times:

1. Use Pre-Approved Standard Plans

An increasing number of cities offer pre-approved ADU plan libraries where homeowners can select from already-reviewed designs, skipping the plan review step (or dramatically shortening it). Check your city's planning department website.

Cities with pre-approved ADU plans: Los Angeles, San Jose, Berkeley (CA), Austin, Portland, Seattle.

2. Hire an Architect or Designer with Local Experience

Permit rejections and revision requests are the biggest timeline killers. A designer who has successfully permitted ADUs in your specific city knows exactly what reviewers look for—dramatically reducing the number of revision cycles.

3. Submit a Complete Application

Incomplete applications are returned without review—restarting your clock. Hire a permit expediter or architect to review your application before submission.

4. Request Pre-Application Consultation

Most planning departments offer a pre-application meeting (free or low-cost) where a planner reviews your concept and identifies potential issues before you invest in full drawings. Use this.

5. Monitor Your Application Status

Don't assume your application is being reviewed. Contact the permit office weekly after submission to confirm receipt, check status, and respond immediately to any requests for additional information.

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Financing While You Wait for Permits

Here's a common scenario: your HELOC is approved, your plans are ready, but permits take 3–4 months. How do you manage?

Good news: Most HELOCs have a 10-year draw period. You don't need to draw until you need to pay. If permits take 4 months, you simply don't draw until construction begins—and you pay no interest on undrawn funds.

Strategies:

• Open your HELOC during the planning/permitting phase (before construction bids)
• Don't draw until you're ready to pay the [contractor](/blog/diy-vs-contractor)'s first invoice
• Use the permitting window to finalize contractor selection and pricing

See [[HELOC for ADU](/blog/heloc-for-adu-construction) Construction](/blog/heloc-for-adu-construction) for how to structure your draw schedule.

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Common Permit Rejection Reasons (And How to Avoid Them)

Setback violations: Your proposed ADU is too close to a property line. Solution: verify setback requirements before designing.

Insufficient ceiling height: Plans show 6'8" finished ceiling; code requires 7'. Solution: check code requirements before starting drawings.

Inadequate natural light: Window area doesn't meet the required percentage of floor area. Solution: add windows in planning.

Missing required documents: Fire sprinkler calculations, engineer's structural letter, energy compliance (Title 24 in CA). Solution: have your architect compile a full checklist before submitting.

Non-compliant kitchen (JADU): Junior ADUs have specific kitchen requirements. Solution: verify JADU-specific code requirements in your jurisdiction.

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Related Articles

• HELOC for ADU Construction
• Detached vs. Attached ADU: Costs and Financing
• [ADU Building Guide: From Concept to [Rental Income](/blog/rental-property-analysis)](/blog/adu-building-guide)
• Garage Apartment Conversion for Rental Income
• California ADU Regulations: Complete Guide 2026
• How Much Can I Borrow With a HELOC?

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Bottom Line

ADU permitting timelines range from 6 weeks in a well-organized Texas city to 18 months in a complex urban jurisdiction. The most important things you can do: hire a designer with local permitting experience, submit a complete application, and use pre-approved plans where available.

Finance your ADU with a HELOC—open it during the permitting phase so it's ready to draw the moment construction begins. Check your HELOC eligibility at HonestCasa and keep your ADU timeline on track from day one.