Wild moment millionaire neighbour is accused of spraying kid next door with a hose as feud over shared terrace escalates in Mosman

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

Marie Barter and Joshua and Michelle Theunissen remain locked in an ongoing legal battle over who has the right to use a 78sqm terrace that sits between their two adjoining properties in Mosman, in Sydney’s lower north shore.

Ms Barter took the matter to the NSW Supreme Court where she sought a ‘declaration’ that her neighbours do not have the sole use of the terrace.

Last week Justice Mark Richmond ruled in Ms Barter’s favour, saying the consultant should have reasonable use of the terrace as it was on her rooftop as long as she didn’t ‘substantially interfere’ with her neighbours’ use of the space.

The Theunissens’ intend to appeal the decision, with Ms Barter seeking compensation in legal costs of up to $200,000.

Now, footage of an ugly clash between Ms Barter and the Theunissens’ teenage son Matt has emerged, seemingly sparked over a stray basketball.

In the video, the 17-year-old is heard asking Ms Barter if he can retrieve his ball from ‘her’ side of the shared driveway, just metres from where he was standing.

‘No, because this is our private property, you’re not allowed to come on it. It’s not your area,’ she told him while continuing to hose her plants.

‘So you’re saying I can’t walk a metre to get my basketball,’ he replied.

Footage of an ugly clash between Ms Barter and the Theunissen’s teenage son Matt has emerged, seemingly sparked over a stray basketball (pictured)

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

‘No, because your not allowed to come on our property, we’ve put it in writing to you. If our car was here it would have damaged it,’ Ms Barter said.

‘That would have been a massive bill.’

The boy disagreed and said if the ball had landed with any impact it would be further down the driveway, instead of stopping where Ms Barter was standing.

Matt then lunged forward to retrieve his basketball, where he claims his neighbour 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.

Ms Theunissen said her son’s back was ‘quite wet’ when he returned home and that her neighbour had called the police and accused him of trespassing.

‘When the police came, I told them about her spraying him with water and the constable said well no one was hurt so it’s fine,’ she told news.com.au.

The court heard that on one occasion Mr Theunissen and his wife (pictured) rang the police, alleging that Ms Barter and her partner were ‘unlawfully intruding on the roof terrace’

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

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

The two properties, which are estimated to be worth over $3million each, sit next to one another on the same piece of land after being split into two lots 30 years ago.

Ms Barter, a consultant, can access the shared rooftop via a skylight and stair ladder while the Theunissen’s can access it via glass sliding doors at the back of their home.

The court heard that on one occasion Mr Theunissen and his wife rang the police, alleging that Ms 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 activity.

The two properties, which are estimated to be worth over $3million each, sit next to one another on the same piece of land after being split into two lots over 30 years ago (pictured)

‘Ms Barter also objects to the Theunissens placing various items on the rooftop, including a basketball hoop, an 8-seater octagonal table, two decorative blue ceramic vases, other pot plants and two gas heaters,’ Justice Richmond wrote.

She also took issue with the Theunissen’s son playing basketball on the roof terrace, which ’causes loud repetitive banging noises that Ms Barter hears throughout her house’ and how the couple allegedly ‘frequently played loud music from the rooftop’.

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

However, Justice Richmond ultimately ruled that the rooftop was a shared space.

‘There is no reason in principle why each of them could not use the rooftop area for that purpose as it is sufficiently large for each to be able to enjoy it without unreasonably interfering with the use by the other,’ he noted in his judgement.

Daily Mail Australia contacted both parties for comment.