Japanese Knotweed is a significant problem across the country. It is an invasive plant that spreads quickly and can grow up to 10cm a day with the roots extending up to three metres deep and seven metres laterally.  It is strong enough to break through concrete and causes considerable damage to buildings and infrastructure. Significantly, it can devalue properties by 5-15% and may in extreme cases completely devalue a property making it not mortgageable.

Downing v Henderson

The buyer, Mr Downing, sued the seller of a £700,000 house in London for misrepresenting whether the property contained Japanese knotweed.

During the transaction, Mr Henderson, the seller, answered ‘no’ to the question on the Property Information Form (TA6 form) asking if the property had ever been affected by knotweed. Both the buyer and seller exchanged contracts and when Mr Downing moved in, he found knotweed at the property.

Mr Henderson claimed that he could not see the knotweed due to a large bush. In reality, the bush had previously stood up to 2m tall and there was evidence it had been treated with herbicide.

Mr Henderson’s defence was dismissed. The judge found that he didn’t genuinely believe that the property was unaffected by knotweed at the time it was sold. Mr Henderson now faces a legal bill of £200,000. From this case, we can see that the court will not look favourably on a seller dishonestly answering this enquiry.

What should a homeowner do when selling or buying a property?

Sellers are obliged to respond to an enquiry on whether or not their property is affected by knotweed on the TA6 form as part of the sale process. Homeowners can only answer ‘no’ if they are absolutely certain there is no knotweed in, or within 3 metres of, the property boundary. If a seller is unsure if knotweed exists or previously existed they should always tick ‘not known’ on the TA6 form. If the property has been or is affected by knotweed, the seller must declare it on the TA6 form and provide the paperwork in relation to the treatment of the knotweed.

A buyer should always get a survey carried out and ensure it includes the garden and, where possible, gardens of adjoining properties.  This applies to flats as well, as knotweed could affect the structure of the building and the cost of remedial works could result in a significant increase in service charge payments.

Can homeowners get insurance indemnity insurance for Japanese knotweed?

Indemnity insurance can provide some protection for buyers and mortgage lenders if knotweed is discovered.  This will generally only be available if no knotweed is present or if it’s been successfully treated in the past. The insurance could cover the cost of a survey report to confirm the presence of knotweed, the cost of treatment and repair of any damage and could extend to defending any legal proceedings in the event of any third party being affected. If such insurance is taken out then the mortgage provider must approve the same in order to protect its interest.

If you have a property which may have Japanese Knotweed or concerns then please contact Attwells Solicitors on 0207 722 9898.

Outside of Essex, London or Suffolk