Revises provisions relating to the Department of Taxation. (BDR 32-1131)

2025 Regular Session

Expands state-level approval and inspection for factory-built developments, allowing unit-by-unit design reuse and private installation inspectors, preempting local review.

(No further action taken.)

Main purpose

AB 557 would amend the California Factory-Built Housing Law to expand state-level approval and inspection authority to certain factory-built "developments," centralize enforcement with the Department of Housing and Community Development (HCD), and streamline approvals by allowing unit-based serial-number approvals that can be reused across projects and building-code cycles.

Key provisions

Defines "factory-built development" as a development project in which factory-built housing constitutes at least 50% of the residential square footage (Health & Safety Code §19970.5).

Requires any factory-built development constructed on or after January 1, 2026, and factory-built housing manufactured after applicable State Building Standards Code effective dates to bear HCD-issued insignia of approval (amends §19980).

Requires HCD to enforce this part of the law (amends §19991) and to make in-plant inspections of factory-built housing.

Removes certain local inspection and enforcement duties (repeals and replaces related sections); prohibits local jurisdictions from demanding plan submittals for approved factory-built housing/developments (amends §19981).

Introduces and defines "installation inspection agency" — private organizations that meet HCD regulations to inspect installations and construction of factory-built developments (new §19975).

Authorizes HCD (and qualified design approval agencies) to approve plans/specifications by unit serial number. Approved unit designs may be reused within the same triennial building-code cycle, and across cycles if relevant factory-built building standards have not changed; HCD/design agencies must limit review to unapproved portions of plans (§19980).

Authorizes licensed architects, under penalty of perjury, to approve factory-built housing and development plans on behalf of HCD (in bill text as amended).

Makes conforming statutory changes; expands enforcement-related criminal provisions (creates a state-mandated local program). Bill states no state reimbursement required.

Who would be affected

Factory-built housing manufacturers and developers (especially projects meeting the 50% threshold).

HCD and qualified private design-approval and installation-inspection agencies.

Local building departments: would be preempted from duplicative plan review and certain inspection roles.

Licensed architects (new authority/ liability to sign approvals under penalty of perjury).

Homebuyers, tenants, and local communities through potential changes in inspection/approval processes.

Procedural status & timeline

Introduced: February 12, 2025.

Passed Assembly: Read third time and passed (Ayes 76, Noes 0) — June 2, 2025; transmitted to Senate.

Referred to Senate committees (Rules, Housing, etc.); was set for a hearing and later canceled at author’s request (committee action July 9, 2025).

Status reported: No further action taken as of the latest update.

Potential impacts & considerations

Centralizes approval/inspection at the state level, potentially speeding multi-project use of unit designs and reducing duplicate local reviews, but shifts inspection/enforcement responsibility away from local governments.

Use of private "installation inspection agencies" and architect approvals raises questions about oversight, liability, and quality assurance.

Preemption language is framed as statewide concern to apply to all cities (including charter cities).

The bill triggers fiscal committee review and states it imposes a local mandate but declares no state reimbursement required.

Bill