01
Ministerial means no hearing
Under § 66317(a)(1) an ADU permit application is considered and approved ministerially, without discretionary review or a hearing, notwithstanding local ordinances on variances or special use permits.
Section 66317(c) goes further: no local ordinance, policy or regulation other than an ADU ordinance consistent with the article may be the basis for delaying or denying a building permit.
In practice this means an ADU application is checked against objective standards. It is not put to a neighbor vote, and objections from neighbors are not a basis for denial.
02
The clock and the record are different things
The statute says 60 days. What jurisdictions actually take is an empirical question, and we measured it from published permit records rather than assuming compliance.
The distinction matters when you are planning. A statutory deadline tells you what you are entitled to; the measured distribution tells you what to budget for. Both are on this site and they do not always agree.
03
Unpermitted units
A large share of the ADU stock was never permitted. Legalizing an existing unpermitted unit is a different process from permitting a new one, with its own evidentiary problems — chiefly proving when the work was done and to which code cycle it must be brought.
California has created routes for this, and the counts of what exists are necessarily estimates. Both research pages below are explicit about the limits of the evidence.