Pressure washing does not appear as its own classification on DOPL’s contractor classification list, which is one reason clients lean on the certificate of insurance instead of a license number as their proof that a vendor is legitimate.
That changes if the work is part of something larger. Utah Code Section 58-55-305 exempts alteration, repair, remodeling, or improvement of a building only below a contracted or agreed value threshold that counts labor and materials together, including all changes and additions. Washing that is genuinely surface cleaning is a different question from washing performed as preparation within a larger restoration, coating, or repair contract. If your scope regularly crosses into surface preparation for painting or coating, the S270 Drywall, Paint, and Plastering classification is worth reviewing.
Because a license number is often not part of the answer, the certificate carries more weight here. Property managers, HOAs, dealerships, and restaurant groups typically want to see general liability, sometimes additional insured status, and increasingly a workers compensation certificate or a Utah Labor Commission waiver if you have no employees.