A recent case was settled at the Central London County Court where a purchaser successfully sued their seller for failing to disclose that a property was affected by Japanese knotweed.

Japanese knotweed is a plant that is non-native to the U.K. It was initially introduced as an ornamental plant, but it is now classified as an invasive species. The plant is known to cause damage to buildings and structures by infiltrating foundations, pavements, tarmac and flood defences. As the plant grows it exploits weak areas in structures which leads to wall cracks and damage to buildings. The costs associated with both repairing the damage caused by the plant and removing the plant from properties are excessive. As such, it is vital that prospective purchasers are informed about the presence of the plant before completing any property transaction.

Since 2013 all sellers must disclose whether their property is affected by Japanese Knotweed in the Law Society's standard Property Information Form (TA6). The presence of Japanese Knotweed in a property can severely reduce the value of the property and can also cause issues for purchasers buying with the assistance of mortgage funds. 

 Furthermore, it is the seller's responsibility to check their garden for Japanese Knotweed and this must be disclosed to any purchaser. 

In this case a purchaser (Mr Downing) bought a three-bedroom house in London for £700,000 from the seller (Mr Henderson). In the sale negotiations the seller stated that the property was not affected by Japanese Knotweed. After the sale completed the purchaser discovered on cleaning the garden that Japanese knotweed was growing next to the garden shed. The purchaser subsequently sued the seller for misrepresentation.

In the case, the seller argued that he 'reasonably believed' the garden was not affected by Japanese Knotweed. The seller argued because the invasive plant was 'hidden' behind another large bush he was unable to see the Japanese knotweed in the garden. 

This was dismissed by the judge as evidence was heard that suggested the knotweed was previously treated with a weed killer. While the seller claimed that he 'did not know' what was behind the garden shed the judge did not accept this argument. It was repeated in the case that it is a seller's responsibility to accurately disclose all items in the Property Information Form and to make the necessary investigations. Simply 'not knowing' was not a sufficient defence. In the deliberations the judge found for the purchaser and awarded the purchaser £32,000 in damages and his own legal costs.