Mr Thompson said the trespassing had been a ''thorn in the side'' of the building's owner for several years.
Now the latest ''fresh'' graffiti of a woman riding a bicycle had ''degraded'' the five-storey building and the graffiti artist would have been at risk.
''It's dangerous to get up and we've had a lot of problems with people trying to get on to the Moran Building roof in the past.
''It's almost like a competition. There's a Facebook page about trying to get on to the Moran Building.''
The trespassing was a ''huge issue'' and the property management company met the building owner yesterday to discuss ways to stop it.
''We are trying to fully solve the problem so no-one can get there.''
There were plans to erect a corrugated iron cage around the fire escape, he said.
''So there's nothing to hold on to and climb up.''
The back of the building was ''barbed-wired up'' but people still managed to get on the roof, he said.
''We know where they are getting in, it's just hard to stop them because they are pretty determined.''
Recently, somebody damaged an exterior heat pump unit when climbing the building and skylights on the roof were consistently being damaged.
In August, Dunedin police arrested a 19-year-old man who had been drinking illegally at a rooftop party at the Moran Building and fell through a skylight.
''They've been replacing two or three skylights on the building every year for the last five or six years.''
The graffiti would be removed as soon as possible, he said.
