Historic Places Trust Otago-Southland regional archaeologist Dr Matthew Schmidt said because the building was unsafe, in this instance an archaeological authority for demolition was not required.
However, it was planned a heritage building specialist would be allowed access to record the site before demolition.
The authority would be required when the building was level, Dr Schmidt said; because the basement and foundations would be handled according to the usual protocols of a historic site.
Not requiring the authority during demolition was reasonably unusual. It happened about once a year, Dr Schmidt said.
Demolition consents for Barrons, and its neighbour the N. and E. S. Paterson building, were signed by the Dunedin City Council earlier this month, after engineers reported the Barrons building was in danger of collapse.
Barrons, which housed Dragon Cafe, partially collapsed on January 12.
Owner of the Barrons building Lincoln Darling said on Friday he had not had a chance to liaise with his insurance broker about when the demolition could take place.
