A long-running dispute in the inner-west suburb of Balmain over the cost of repairing a brick boundary wall could become one of Sydney‘s most expensive neighbour disputes.

Macquarie University professor Catherine McMahon and her husband Neil Bryant have sent their neighbour a $60,000 invoice for repairs to a shared wall they say was damaged by work done on it in 2022.

The lawyer’s letter included a clause demanding interest of 29 per cent per month on any unpaid balance – a rate that if ever enforced, could balloon the debt into a massive sum. 

After just one year, the total would climb past $1million.

The letter also warned that if builders were denied or delayed access to carry out repairs, the neighbour would be charged $250 an hour plus GST.

The dispute began after McMahon and Bryant claimed the neighbour and contractors used sledgehammers to demolish part of a shared brick wall that separated their properties, despite an engineer’s report recommending that a diamond-blade saw be used to carefully divide two adjoining walls.

McMahon and Bryant claim the rough demolition damaged their side of the structure, which also served as a retaining wall between the properties. 

They allege  the neighbour then failed to stabilise or repair the wall, causing further deterioration and inflating the eventual repair bill.

Catherine McMahon (pictured) is involved in a long running dispute over a damaged fence

Catherine McMahon (pictured) is involved in a long running dispute over a damaged fence

The legal notice was issued by Professor Catherine McMahon who lives with her husband Neil Bryant whose home share a rear boundary although they are on different streets

The legal notice was issued by Professor Catherine McMahon who lives with her husband Neil Bryant whose home share a rear boundary although they are on different streets

A Balmain family has received a legal letter demanding repairs to a backyard boundary fence with a staggering 29 per cent interest rate to be applied monthly if the work is not carried out

A Balmain family has received a legal letter demanding repairs to a backyard boundary fence with a staggering 29 per cent interest rate to be applied monthly if the work is not carried out

After the alleged damage, the couple arranged repairs, and issued a formal ‘Notice to Carry Out Fencing Work’ under Section 11(1) of the Dividing Fences Act 1991 (NSW), demanding that their neighbour contribute to the cost.

The demand, sent through law firm Lion Legal, included the builder’s quote for the work and the steep penalty clauses covering any interest and access delays.

Lion Legal solicitor Nasir Hanafi, acting on behalf of Professor McMahon, declined to comment on the ongoing proceedings.

The matter is expected to go to court next month.

Lawyer Andrew Carpenter said the case serves as a cautionary tale for homeowners that even seemingly minor property issues can escalate into complex and costly legal battles.

Mr Carpenter said he had witnessed people lose their homes over a neighbourhood dispute. 

‘I did one recently where there was a $13,000 fence, and both parties spent in excess of $200,000 on legal fees over this,’ he said.

‘Fencing disputes can be a lot like family law, where it’s based on emotions rather than economic sense. 

The legal notice was issued by Professor Catherine McMahon and her husband Neil Bryant whose home share a rear boundary although they are on different streets

The legal notice was issued by Professor Catherine McMahon and her husband Neil Bryant whose home share a rear boundary although they are on different streets

Lawyer Andrew Carpenter ( pictured) said neighbourhood disputes can prove costly

Lawyer Andrew Carpenter ( pictured) said neighbourhood disputes can prove costly

‘These people are going to be spending more on legal fees than what the fence is worth.’ 

He said parties are free to set their own interest rates in private contracts, but courts can overrule that. 

Mr Carpenter said generally the interest that can legitimately claimed is four per cent above the RBA cash rate, which currently sits at 3.6 per cent. 

‘The only time that you can attempt to claim a high interest rate would be if the parties have signed a contract before agreeing to a specific interest rate,’ he said.

‘But even if that’s the case, courts can then set them aside if they seem to be manifestly excessive. 

‘What we’ve seen in recent times is people believe that they know the law, and they issue letters claiming absurd costs or interest rates which simply are not enforceable in court.’

Mr Carpenter said lawyers were bound to act on their clients instructions so a claim of 29 per cent would have been set by the client, not the law firm.

‘If you’re doing something like this to your neighbour, it’s going to firstly, sour the relationship, but secondly, it’s going to make you look silly, because there’s no way in hell a court will ever enforce interest rate like that,’ he said.

‘It’s just a scare tactic, but it’s also unenforceable, because I don’t see anyone that can justify 29 per cent per month at interest rate for for a fence repair.’

It isn’t the first time the prestigious Balmain postcode has made headlines for high-stakes neighbourly feuds. 

In 2019, a long-running dispute between residents escalated into defamation claims, AVOs, and even a segment on A Current Affair. 

Vanessa Hutley (pictured) first took issue with builder Anthony Cosco when he and his family moved into the house next door in Balmain in 2013

Vanessa Hutley (pictured) first took issue with builder Anthony Cosco when he and his family moved into the house next door in Balmain in 2013

Builder Anthony Cosco (pictured) launched defamation proceedings against Ms Hutley after she accused him of bullying and putting her life in danger during an ACA episode in 2016

Builder Anthony Cosco (pictured) launched defamation proceedings against Ms Hutley after she accused him of bullying and putting her life in danger during an ACA episode in 2016

Lawyer Vanessa Hutley was ordered to pay her tradesman neighbour $300,000 after a bitter row over a fence ended in a rant on national TV.

Ms Hutley accused builder Anthony Cosco of bullying her and her family and making their lives ‘hell’ during an A Current Affair segment in June 2016.

Mr Cosco launched defamation proceedings against Ms Hutley following the segment. 

Justice Stephen Rothman ruled Ms Hutley had bullied and defamed Mr Cosco and had ‘displayed an abysmal arrogance and sense of privilege’.

The dispute began when Mr Cosco moved into his $1.75million home in 2013 and began erecting a tall fence between the properties.

In the following years, the dispute escalated to the point that both parties took out AVOs against each other.

Mr Cosco had pleaded guilty to malicious damage after he sprayed expanding foam into a vent leading to Ms Hutley’s property after she refused to move it.