5 county-level rules, plus city-specific rules for 4 cities in Collin County, Texas.
Verified from official government sources
Collin County has no zoning authority over ADUs in unincorporated areas. Property owners may build accessory dwelling units, guest houses, or casitas without county zoning approval, subject only to IRC building permits, septic permits (On-Site Sewage Facility rules), and any deed restrictions/HOA rules.
Sheds in unincorporated Collin County require a building permit only if over 200 sq ft (per IRC) or if electrical/plumbing is installed. No setback or height limits at county level. Floodplain Development Permit required if in a FEMA Special Flood Hazard Area.
Garage conversions in unincorporated Collin County require building permits for any structural, electrical, plumbing, or mechanical work under IRC. No zoning limits apply since counties cannot zone. Conversions affecting septic loading require OSSF review. HOAs and deed restrictions commonly prohibit or tightly regulate conversions.
Carports in unincorporated Collin County require building permits for permanent structures attached or with foundations, but metal carports placed on gravel/dirt without foundation often qualify as temporary and are permit-exempt if under 200 sq ft. No county setback or material rules. HOAs often ban metal carports.
Tiny homes on foundations are regulated in unincorporated Collin County only through IRC building code (min 70 sq ft habitable room, IRC Appendix Q for tiny houses under 400 sq ft). Tiny homes on wheels are RVs under TX Transportation Code and cannot legally serve as permanent residences outside RV parks.
4 cities in Collin County have their own accessory structures rules. Each link goes to that city's dedicated page with code citations.
See every category we cover for Collin County — parking, noise, fences, fires, animals, pools, and more.
Collin County Ordinance Hub →