Leveling the Playing Field for Factory-Built Housing: Why HAC Supports AB 1815
California has spent the better part of a decade removing the regulatory barriers that make it difficult to build much-needed new homes. We’ve reformed land use rules, streamlined permitting, and limited local veto power over projects we desperately need. But one underappreciated obstacle remains: the fragmented, and inconsistent local building standards that make it nearly impossible to scale factory-built housing at the speed and cost the state needs.
Assembly Bill 1815, authored by Assemblymember Buffy Wicks, directly addresses that problem. The bill prohibits local jurisdictions from imposing or enforcing building standards on factory-built housing projects that exceed California’s state minimum building standards. The fix sounds simple — and in concept, it is. But the impact could be substantial.
Why local standards are the problem
Off-site construction reliably cuts construction timelines by 10 to 30 percent, according to analysis by the Terner Center for Housing Innovation, with some estimates putting the figure closer to 50 percent. Those savings come from the factory environment itself: standardized processes, bulk materials purchasing, parallel workflows. But those efficiencies evaporate when a developer has to retool a unit design every time they cross a city or county line because local building requirements differ from state standards.
Factory-built housing is defined as a residential building, dwelling unit, or building components manufactured so that all concealed parts or processes of manufacturing cannot be inspected before installation. By design, these units are manufactured before they arrive on site. When local jurisdictions layer additional building standards on top of state minimums after the fact, it undermines the entire production model by creating costly redesigns, inspection delays, and project-by-project uncertainty that drives up costs and discourages developers from going the factory-built route in the first place.
AB 1815’s origin
AB 1815 is part of Assemblymember Wicks’ broader 2026 housing construction innovation package. After a 2024 series of select committee hearings on permitting reform that produced nearly two dozen housing bills the following year, Wicks has turned her attention to construction costs — the next frontier the legislature has yet to meaningfully tackle. As she put it: “Over the last eight to 10 years or so the Legislature and the governor have really taken a bulldozer to a lot of the bureaucratic hurdles when it comes to housing. But one of the issues that we haven’t fundamentally tackled is the cost of construction.”
The effort comes amid growing developer and investor interest in modular and prefabricated construction, with policymakers hoping to harness the speed, efficiency, and cost-savings of assembly-line construction to address the housing crisis. AB 1815 doesn’t fund factories or mandate their use, it simply removes a regulatory roadblock so that developers who want to use this construction method can actually make the economics work.
Why HAC is proud to sponsor AB 1815
HAC’s members: developers, architects, contractors, laborers, all know firsthand how local building standard variability adds cost and complexity to projects. Factory-built construction holds real promise for delivering more homes faster and at lower cost, particularly for multifamily and affordable housing. But that promise can only be realized at scale if the regulatory environment supports it.
AB 1815 is a straightforward, pro-housing measure that advances a statewide interest: more homes, built faster, for less. We’re proud to sponsor the bill with the California Housing Consortium and urge the legislature to move it forward.
