Original data study

ADU Permit Complexity Index (2026)

Which U.S. cities have the hardest ADU (accessory dwelling unit) permitting — and which make it easiest? We ranked 108 jurisdictions using only real, source-cited permit-requirement data.

Last reviewed: June 22, 2026

The 10 hardest and 10 easiest

Higher scores mean a heavier, more uncertain permit package. Each jurisdiction links to its full cited checklist.

Full ranking — all 108 jurisdictions

Sort by complexity, required documents, or name. Filter to cities or statewide baselines.

How we measured this

Frequently asked questions

Which U.S. cities have the hardest ADU permitting?

In ArchPermit's index of 108 jurisdictions, the cities with the highest ADU permit complexity scores are Denver, Colorado (score 62.1, 14 required documents); San Diego, California (score 61.3, 12 required documents); Miami, Florida (score 61, 8 required documents). Scores are derived from each jurisdiction's source-cited ADU requirement set.

How is the ADU permit complexity score calculated?

Each jurisdiction is scored 0–100 (higher = harder) from real, source-cited data only: the count of required ADU documents (the largest factor), the count of conditional items, the number of items flagged to verify locally, whether a binding statewide ADU law applies, and whether an electronic submission portal exists. Only jurisdictions with cited ADU requirement data are ranked — nothing is estimated or invented.

How many documents does a typical ADU permit require?

Across the 108 ranked jurisdictions, the median jurisdiction lists 13 cited ADU permit requirements, of which a median of 11 are mandatory. The full set spans 1,430 individually source-cited requirements.

Do statewide ADU laws make permitting easier?

A binding statewide ADU law standardizes baseline rules local agencies must follow, which lowers a state's complexity score in this index. 19 of the ranked statewide baselines have such a law; California is among the lowest-complexity baselines.