For residential building projects, including roof work, yard wall construction, porches, or sheds, the homeowner can request the permit and do the work themselves. All heating and cooling work must be completed and permitted by a contractor holding the appropriate license.
For plumbing and electrical work, there is a written test that the city will administer. If you pass the test, you can do the work on your own. If not, you will need to hire a licensed contractor. Anytime you are paying someone else for contracting services, they must be licensed and they must request a permit.