Dallas County is highly urbanized with most land incorporated into cities that manage their own building permits, zoning, and inspections. The County Fire Marshal primarily exercises jurisdiction over unincorporated areas and specific county-owned facilities. Development in unincorporated areas is subject to county subdivision regulations and floodplain management requirements.
How this fits with the state
The state authority here is Texas Department of Licensing and Regulation; Texas State Board of Plumbing Examiners. The county file does not replace that — it adds the permit office, local overlays, and the actual filing path.