It is LEGAL to carry a firearm onto any private property or businesses, even if they have a “No Weapon” or “No Firearm” sign. Utah law 76-8-311.1 (1)(a)(vii)(B) says a “secure area” may not include any area normally accessible to the public. This means that businesses that post these signs Do Not have the force of law.
However, a private property owner may have policies that can restrict a person from carrying or possessing a firearm. If the owner, manager, or other employee suspects you of violating a policy, they have the right to tell you to leave the property. If you refuse to leave, you can be charged with criminal offenses such as criminal trespass and/or disorderly conduct. Always be aware that the responding law enforcement, who may have been called without your knowledge, could arrest you even if you think you are within the law.
Utah law protects property owners from civil or criminal liability for any damage or harm resulting from the discharge of a firearm by an individual on the property, provided the property owner knowingly allows the individual to lawfully bring a firearm onto the property.
The only places where firearms and ammunition are prohibited are specifically designated state-restricted and federal-restricted areas.