Congress is moving to eliminate a five-decade-old requirement that manufactured homes be built on permanent steel chassis, a rule that adds thousands of dollars to each unit and limits design flexibility. Both the Senate and House have approved versions of a sweeping housing bill that include the provision to scrap the 1974 mandate.

The chassis requirement was originally designed for truly mobile homes that owners moved across the country in search of work. But housing experts say the rule is now obsolete since most manufactured homes remain permanently parked once installed in trailer parks or residential neighborhoods. Manufacturers cannot remove and reuse the frames, passing unnecessary costs to consumers.

Industry executives and housing advocates argue removing the requirement would open urban development opportunities for factory-built homes, allowing designs suited for smaller lots where affordable housing is desperately needed. However, the Modular Home Builders Association opposes the change, arguing it would create consumer confusion about quality differences between manufactured and modular homes.

The legislation still needs to be reconciled between chambers before reaching President Trump's desk. Previous attempts to eliminate the chassis requirement fizzled in the 1990s and again in 2023, but housing advocates say the current bipartisan push for affordable housing solutions makes passage more likely this time.