CA AB1815

Prohibits cities and counties from imposing building standards that exceed California's minimum Building Standards Code on housing projects using factory-built housing, when at least 15% of the project's hard costs are spent on factory-built housing bearing Department of Housing and Community Development insignia

Defines "hard costs" as the total cost of labor and materials required for the construction scope

Preserves local authority over use zoning, snow load requirements, wind pressure requirements, fire zones, building setbacks, side and rear yard requirements, site development, property line requirements, and architectural/aesthetic review

Declares housing provision a matter of statewide concern, making the bill applicable to all cities including charter cities

Expands the scope of existing misdemeanor violations under the California Factory-Built Housing Law, creating a state-mandated local program