Willis, TX Accessory Structures: Tiny Homes (2026)

Texas tiny home regulation depends heavily on construction type. (1) Foundation-built tiny homes are dwellings subject to local building code. Texas adopted the 2021 IRC including Appendix Q (Tiny Houses), which allows homes under 400 sq ft with reduced stair/ladder/loft requirements. Within Conroe city limits, UDC §3.02 imposes a 600 sq ft minimum dwelling unit for detached single-family — tiny homes below that size are not permitted as primary dwellings, though ADU rules permit detached accessory units 300-900 sq ft on qualifying lots. (2) Tiny Homes on Wheels (THOWs) certified to ANSI A119.5 are park model RVs under TX Occupations Code Ch. 1201 Texas Manufactured Housing Act — they are vehicles, not dwellings, and cannot be used as permanent residences except in licensed RV parks or manufactured home communities. (3) HUD-code manufactured homes are protected under Property Code §233.153 — counties and cities cannot prohibit them in residential areas subject to limited appearance standards. In unincorporated Montgomery County, with no zoning, foundation tiny homes on private land are legal subject to septic/OSSF permits through the county environmental health department and deed restrictions. The Woodlands prohibits structures under residential covenants; Lake Conroe subdivisions universally ban tiny homes and mobile homes. Utility hookups (well, septic/OSSF, electric) are required for permanent occupancy.