225 ILCS 317/15

(a) It shall be unlawful for any person to engage in, advertise, or hold itself out to be in the business of providing service for fire sprinkler systems in this State unless such person is licensed by the Office. (b) Applications for initial licensure and renewal shall be made to the Office on forms or electronically as prescribed by the Office, and applicants shall pay the license fee. (c) No license is required for a person or business that is engaged in the installation of fire sprinkler systems only in single-family or multiple-family residential dwellings up to and including 8 family units that do not exceed 2 1/2 stories in height from the lowest grade level.