Millionaire neighbor’s wild moment accused of spraying boy next door with a hose as feud over shared terrace in Mosman escalates

A bitter legal battle over a shared terrace atop a house in one of Australia’s swankiest suburbs has erupted after one of the millionaire homeowners allegedly sprayed her neighbour’s son with a garden hose.

Marie Barter, Joshua and Michelle Theunissen remain embroiled in an ongoing legal battle over who has the right to use a 78m² terrace located between their two adjacent properties in Mosman, on Sydney’s lower north shore.

Ms Barter has taken the matter to the NSW Supreme Court, where she sought a ‘declaration’ that her neighbors do not have exclusive use of the terrace.

Last week, Judge Mark Richmond ruled in Ms Barter’s favour, saying the consultant had to make reasonable use of the terrace as it was on her roof, as long as she did not ‘substantially interfere’ with her neighbours’ use of the space.

The Theunissens plan to appeal the decision, with Ms Barter seeking damages towards legal costs of up to $200,000.

Now footage has emerged of an ugly collision between Mrs Barter and the Theunissens’ teenage son, Matt, apparently caused by a stray basketball.

In the video, 17-year-old Ms. Barter can be heard asking if he can retrieve his ball from “her” side of the shared driveway, just feet from where it was standing.

‘No, because this is our private property, you are not allowed on it. It’s not your area,” she told him as she continued to hose down her plants.

“So you’re saying I can’t walk a yard to get my basketball,” he replied.

Mosman consultant Marie Barter (pictured) has sued her neighbors Joshua Theunissen and his wife Michelle over who has the right to use a 78sqm terrace located between their two adjacent properties in Sydney’s lower north shore.

‘No, because you are not allowed on our property, we have informed you of this in writing. If our car had been here it would have been damaged,” Ms Barter said.

“That would have been a huge bill.”

The boy disagreed, saying that if the ball had landed with any impact, it would have been further down the driveway, instead of stopping where Mrs. Barter was standing.

Matt then jumped over to retrieve his basketball, where he claims his neighbor sprayed him with her hose after he turned his back.

“Did you actually just spray me with water? I don’t know why,” he said in the video.

Mrs Theunissen said her son’s back was ‘quite wet’ when he got home and that her neighbor called the police and accused him of trespassing.

“When the police came I told them she sprayed him with water and the officer said no one was hurt so it’s fine,” she said. news.com.au.

The court heard that at one point Mr Theunissen and his wife (pictured) called the police, claiming that Ms Barter and her partner were ‘unlawfully trespassing on the roof terrace’.

The roof terrace, 78 square meters in size, can be seen on the right of the aerial photo above

She said Ms Barter had moved into the house in 2008, but confrontations over shared parts of the property had started in 2019.

The two properties, each estimated to be worth more than $3 million, are next to each other on the same plot of land after being split into two parcels 30 years ago.

Mrs. Barter, a consultant, accesses the shared roof via a skylight and a stepladder, while the Theunissen’s access it through sliding glass doors at the back of their home.

The court heard that Mr Theunissen and his wife once called the police, claiming that Mrs Barter and her partner were ‘unlawfully intruding’ on the terrace.

They also alleged that Ms Barter’s partner had assaulted Ms Theunissen.

In response, both parties installed CCTV cameras on the roof terrace to ‘monitor’ each other’s activities.

The two properties, each estimated to be worth more than $3 million, are next to each other on the same plot of land after being split into two parcels more than 30 years ago (pictured)

“Ms. Barter also objects to the Theunissens placing several items on the roof, including a basketball hoop, an octagonal table for eight people, two decorative blue ceramic vases, other potted plants and two gas heaters,” Judge Richmond wrote.

She also objected to the fact that Theunissen’s son played basketball on the roof deck, which caused “loud repetitive popping noises that Mrs. Barter hears throughout her home” and that the couple “often played loud music from the roof.”

The Theunissen argued that they were entitled to exclusive use of the roof terrace and that Mrs. Barter’s skylight was only added later.

However, Judge Richmond ultimately ruled that the roof was a shared space.

“There is no reason in principle why each of them should not be able to use the roof area for that purpose as it is of sufficient size to enable them to enjoy it without unreasonably interfering with the use of the other,” he noted in his judgement.

Daily Mail Australia has contacted both parties for comment.