Commercial Update 89: Knotty Problems of a Japanese Variety

Japanese knotweed has long been a concern for homeowners – this is a plant that is non-native to the U.K, initially introduced as an ornamental plant, but now classified as an invasive species. It can cause damage to buildings and structures by infiltrating foundations, pavements, tarmac and even flood defences. It’s estimated to be behind about £170 million of home repairs every year, it can devalue properties by 5-15% and in extreme cases completely devalue a property rendering it un-mortgageable – particularly if the buildings insurance policy doesn’t cover knotweed.

Knotweed must be dealt with straight away. If a homeowner fails to do this, they could face a hefty claim from adjoining landowners. This claim could be for the costs of removing the knotweed but also for the decrease in value of the adjoining property.

Since 2013 sellers are obliged to respond to an enquiry on whether or not their residential property is affected by knotweed on the TA6 form as part of the sale process. This enquiry was revised in February 2020, so now homeowners can only answer ‘no’ if they are absolutely certain there is no knotweed in, or within 3 metres of, the property boundary.

In the case of Downing v Henderson, we have a purchaser buying a three-bedroom house where in the sale negotiations, the seller stated that the property was not affected by Japanese Knotweed – the inevitable then happened in that after completion, the purchaser discovered Japanese knotweed was growing next to the garden shed.

The seller argued that he ‘reasonably believed’ the garden was not affected by Japanese Knotweed. This was dismissed by the judge as evidence was heard that suggested the knotweed was previously treated with a weed killer by the seller.

In conclusion, as this case confirms, the court will not look favourably on a seller dishonestly answering this enquiry. 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 and will not be a sufficient defence. If a seller is unsure if knotweed exists or previously existed they should always tick ‘not known’ on the TA6 form.

Any buyers out there should always get a survey carried out and ensure it includes the garden and, where possible, gardens/sites of adjoining properties. This applies to flats/commercial properties as well, since the presence of knotweed could affect the structure of the building and the cost of remedial works could result in a significant increase in service charge payments. There is both case law and legal precedent that says that surveyors must fulfil their duty of care to a buyer by identifying the invasive plant and if they fail to do so, they could be sued for negligence.

Final thought – Whilst most buildings insurers don’t ask about knotweed, they may not cover any treatment so a careful check of the insurance policy may be worth doing.

Regards to all