The owners of a Christchurch mansion which went up in smoke on Friday night say they tried their best to protect the property.

A person will appear in the Youth Court next week over the fire at Antonio Hall, which started around 5.30 Friday afternoon, which significantly damaged the already-derelict building.

But heritage groups say the building's fiery fate was inevitable, due to the state of disrepair it was constantly in and the reputation it'd gained for squatters and parties.

Property manager Sam Yau says he lived in the building himself until it was damaged in the Christchurch earthquake.

He says after that, the owners installed 24-hour CCTV and alarms.

"We respond to every alarm. We check alarms every 20 minutes, but unfortunately, this time, within 20 minutes is not enough."

He says they have handed over some of the footage from their cameras to Police.

Yau says that burglaries and vandalism were common at the former Catholic seminary.

"We got burgled very often, and we reported to Police, and Police visited thousands of times."

He says he has been in touch with the owners, who had plans to renovate the heritage building and turn it into a hotel.

"It is a bit sad for everybody, and I know a lot of people like the building as well, and so do we."