Employees working at the Paul Martin building in downtown Windsor will likely have to use a different entrance to get into the building for the next while.
A federal health and safety officer locked the entrances on Ouellette Avenue and Pitt Street.
A signs on those doors read, "danger of falling stone."
Marc Briere is with the union representing the more than 300 Canada Revenue employees who work in the heritage building.
"We are not happy with the situation, that's obvious," he said. "Our first and foremost priority is the well being of our members, the CRA - and of the public, also. Obviously we do not want anybody to get hurt."
Briere says employees will likely have to use an alternate entrance, on the back side of the building.
He said an investigation is taking place that needs to run its course.
Briere is concerned Public Works knew there was a problem with the entrances, and did not contact the union.
"Public Works being the owner of the building, by law, by the Canada Labour Code, they have to ensure that the building is safe for workers and for the public, too," Briere said.
Downtown Windsor Business Improvement Association president Larry Horwitz said he is aware of the situation.
He said that he and some of the other nearby business owner will be meeting about the situation Wednesday.
Calls to Coun. Fulvio Valentinis, Coun. Bill Marra, Essex Conservative MP Jeff Watson and the Ministry of Labour were not returned.