A "unique" quickfire demolition of an eight-storey earthquake-damaged Christchurch office block will be done in 48 hours this weekend.

The owners of URS House, on the corner of Gloucester and Durham streets, have chosen to demolish rather than repair, and they are managing the demolition works privately.

They plan to level the former office tower in under 48 hours, with two separate crews using two high-reach excavators.

Demolition experts will work from 7am to 10pm to reduce the building to rubble, which will be removed as the work is completed, the Canterbury Earthquake Recovery Authority said today.


Work will only continue after 10pm if there is a safety issue with the state of the building.

The use of the heavy machinery will require the roads around the building to be closed from 7pm on Friday to 6am on Monday, which means the Durham St one-way system will be partially closed.

Suggested detours will be signposted.

In the event of any unplanned delay, a contingency traffic management plan will be put in place by the Christchurch City Council on Monday to minimise any disruption.