A brick heritage building in downtown Ottawa that partially collapsed a month ago, forcing the closure of a major intersection, must be demolished, the city has announced.

The recent freezing and thawing, along with the weight of ice and snow have further jeopardized the stability of Somerset House at the southeast corner of Bank and Somerset Streets, while preventing necessary stabilization work, said Arlene Gregoire, the city's director of building code services Monday.

The City of Ottawa estimated it could take 10 days to complete preparations for the demolition of Somerset House.
(CBC)

"It's only as a result of the weather and all of the combination of factors that we have now, in essence, given up on the building," she said. "We have no choice … I just can't assure the safety of the public anymore."

The city issued the emergency demolition order for the building on Friday.

"[The building] is now in a significant state of instability to the point that it is not a matter of could the building collapse, but a matter of when the building will collapse," the city said in a statement.

The city estimates that preparations for demolition, such as shutting off water sewer and gas, could take up to 10 days because of the complexity of the site.

The building is so precarious that workers are banned from approaching within five metres of the outside walls, Gregoire said. The city is also concerned that vibrations caused by heavy machinery, such as a wrecking crane, might cause a sudden collapse.

The cost of demolition, along with the cost of policing and keeping adjacent roads closed since the building's partial collapse on Oct. 19, will be billed to building's owner, Gregoire said.

City staff had hoped the heritage building could be saved, she added.

Arlene Gregoire, the city's director of building code services, said city fears vibrations from heavy machinery such as a wrecking crane could cause a sudden, uncontrolled collapse.
(CBC)

However, on Nov. 18, engineers discovered voids beneath the foundations and walls that needed to be filled in order to restore the building's stability. Those voids were created by the owner scooping out crushed rock so it could be replaced with a stronger foundation. There was a plan to pump grout into those voids on Wednesday, but a snowstorm made that impossible.

Engineers are trying to determine whether it might still be possible to save some of the building's walls, Gregoire said.