Police have issued trespass notices to the teenagers, aged between 14 and 16, after Riccarton House was hit four times in one week.
In the most recent event last Saturday, a small fire was started on a riverbank located on the property.
The heritage site’s manager Shona Willis said there were about six youths caught on security cameras when the fire was started.
Police and a fire crew were called to the scene, and the teenagers fled, she said.
But the same group returned later that night.
Mrs Willis immediately called the police and the teenagers were spoken to.
She said three of them regularly seen on the grounds were trespassed.
The trespass notices will last two years.
“Hopefully we are at the end of it,” Mrs Willis said.
However, she said the youths returned briefly in spite of the trespass notices being issued.
Mrs Willis said the restaurant owner approached the vehicle, occupied by at least two youths, and warned them a trespass notice had been issued and would phone police.
The vehicle then left.
Before then on January 5, the site’s public toilets – including a toilet roll holder, soap dispenser and air dryer was damaged between 5.30 and 8.30pm.
Mrs Willis said it was suspected an ignited aerosol can was used to vandalise the facilities - resulting in about $500 in damage.
She said security cameras captured about five youths along with a car registration plate on the night the damage took place.
The toilets are connected to the historic house, but can only be accessed from the outside of the building.
Eight youths then spray-painted obscenities and racist remarks on the driveway, Mrs Willis said.
In a third incident, about 15 teenagers placed a pile of rubbish on top of a picnic table and set it on fire - leaving the picnic table charred.
