Most contractors are required to be licensed: electrical, mechanical, irrigators, and plumbing contractors. However, there are some exceptions.
General contractors do not have any licenses, but a property owner should ask their contractor if they are registered with the City of Irving before beginning. If a contractor asks you to apply for the building permit, chances are that they may not be registered because the city verifies applicable contractor licensing with the State of Texas for all building permit applications.
Homesteaded residents do not have to be licensed to perform work on their own home in most cases.
For questions about contractor registration, contact the City of Irving Building Inspections Department at (972) 721-2371.