Gaithersburg, MD Accessory Structures: Tiny Homes (2026)

Gaithersburg does not have a standalone tiny home ordinance, but tiny homes are regulated through existing building and zoning codes. Tiny homes built on permanent foundations may be permitted as primary dwellings or accessory dwelling units if they meet all IRC standards. The 2018 and later IRC includes Appendix Q provisions for tiny houses, establishing a minimum habitable room area of 70 square feet and a minimum dwelling size of approximately 150 square feet. Ceiling heights may be reduced to 6 feet 8 inches in lofts and 6 feet 4 inches under loft floors. Loft areas must have at least 35 square feet of floor space. Tiny homes on permanent foundations used as ADUs follow Gaithersburg's accessory dwelling unit regulations including the owner-occupancy requirement and 1,200-square-foot maximum. Tiny homes on wheels (THOWs) are classified as recreational vehicles or trailers under Maryland law and cannot be used as permanent dwellings. They may not be connected to utilities for habitation on residential lots. Manufactured homes must comply with HUD standards and local zoning for manufactured housing. Contact the Building Division at (301) 258-6330 for pre-application guidance on tiny home projects.