Delta Pty Ltd yesterday pleaded guilty to failing to comply with a prohibition notice after a WorkSafe inspector noticed a person standing at an exposed edge two stories up on November 9, 2006.

The court heard there were no railings or safety measures in place and a notice was issued to the company.

However, a second incident followed on November 24 when two people, including a health and safety officer for the company, were observed on on the roof of a building at the Mair St site hosing the area with water to suppress dust.

WorkSafe prosecutor Karen Argiopoulos said the only barrier on the roof was a low parapet.

Ms Argiopoulos said the parapet was only 420mm high and was too low to offer any protection for the workers, who were 20m from the ground.

The court heard Delta Pty Ltd was an Australian-owned company with two prior findings of guilty before the courts.

Delta counsel Robert Taylor said the man involved in the first instance had been at the unprotected edge for a "sticky beak" rather than work purposes.

Mr Taylor said the company had health and safety induction processes in place and there was a "measure of startled frustration" at the situation from senior levels.

Magistrate Kay Robertson said demolition work was dangerous by its very nature but the risk must be minimised.

"The penalty has to send out a message that it does not work to not comply with notices," she said.

Ms Robertson fined Delta Pty Ltd $48,000 and ordered the company to pay costs.