A handful of laborers from construction union Local 261 picketed the fire-plagued building at Mission and 22nd on Thursday and Friday to protest the use of non-union workers by a drilling company engaged in the building’s demolition.

Hawk Lou, the building’s owner, received an emergency order from the city in February to begin  demolition of the building to street level. The order came more than a year after a fire at the three-story building killed one man and displaced dozens of commercial and residential tenants.

Following the emergency order, Lou pulled permits to begin demolition, but no work started on the building until after a second fire erupted there on March 14. The following day fences went up around the building and crews began manually tearing down the roof from the inside.

The Department of Building Inspection said last week that they expected demolition to be finished within four to six weeks.

On Thursday afternoon, five men were on site with signs reading “Unfair” above “Ace Drilling,” the construction firm hired by the building’s owner. The firm is not using union workers for work on the building, according to Josh Arce, a candidate for District 9 supervisor and community liaison for Local 261.

“After a year of inaction, the building owner has now brought in contractors to work on the building that are undermining local workers’ wages and raising questions about the quality of the work being performed,” he wrote in an email.

Neither Lou’s attorney nor Ace Drilling could be reached for comment.

William Strawn, a manager of public and legislative affairs at the Department of Building Inspection, said the department has no policy on requiring union labor and that any qualified firm could perform the demolition.

Arce also said his union sent a letter to the Mayor’s Office of Housing, the Department of Building Inspections, and the mayor asking for a commitment that no permits be issued until there is confirmation that the building’s former tenants would preserve the right to return to their old units at the former rent.

The fate of the building’s tenants was in question in February because the order for demolition seemed to eliminate that right.

Outcry from advocates and Supervisor David Campos followed the news, and the Department of Building Inspection clarified that original building will legally still exist following the demolition, preserving the rent-controlled units on-site and the right of return of tenants.

The fate of the subsequent building is still in question. The Mission Economic Development Agency offered to buy the building in August 2015 and turn it into permanently affordable housing for an undisclosed amount.

That offer was turned down then, and sources close to the negotiations said the landlord was looking to sell the building for $20 million. MEDA recently redoubled its call for the landlord to sell to an affordable housing developer.

“We are concerned that this could be a ploy to demolish the building before the community can buy it,” Arce wrote.