Why can’t the tiny homes be bigger than 399sq ft?

To maintain an RV designation, homes are typically designed at or under 400 square feet and built to RV standards rather than traditional housing codes. Homes exceeding this size generally fall under HUD or standard residential building codes, which can classify them as real property and subject them to different zoning and property tax rules. Lofts and covered porches can add usable living space without being included in the official square-footage calculation. This allows for a more open, functional design while staying within regulatory guidelines.