Japanese Knotweed, Legal Obligations for Sellers, Buyers and Owners

Why Japanese Knotweed is a Property Issue

Japanese knotweed (Fallopia japonica) is an invasive plant capable of causing structural damage to buildings, drains, and hard surfaces. Its root system, the rhizome, can extend several metres horizontally and several metres deep, penetrating concrete, cavity walls, and drainage systems over time.

Beyond the physical damage, Japanese knotweed has become a significant legal and financial issue in the UK property market. Mortgage lenders commonly refuse to lend on affected properties without a professional management plan in place.

Obligations on Sellers

Sellers in England and Wales complete a Property Information Form (TA6) as part of the conveyancing process. The TA6 includes a direct question about Japanese knotweed. Sellers must answer accurately and honestly.

Knowingly providing a false answer is a misrepresentation. Buyers who later discover undisclosed knotweed can bring a civil claim against the seller, and there have been multiple reported cases where sellers have been ordered to pay substantial damages.

Obligations on Owners

Under the Wildlife and Countryside Act 1981, it is not an offence to have Japanese knotweed on your land, but it is an offence to cause or allow it to spread onto neighbouring land. Waste containing knotweed is classified as controlled waste under the Environmental Protection Act 1990 and must be handled by a licensed waste contractor.

How Mortgage Lenders Treat Knotweed

RICS published a revised information paper in 2022 introducing a risk categorisation system:

• Category 1 (Low risk), Knotweed more than 7 metres from any habitable space, or eradicated with a valid 10-year guarantee
• Category 2 (Medium risk), Within 7 metres but no structural damage evident
• Category 3 (High risk), Evidence of structural damage or knotweed within or affecting a structure

Lenders typically require a Category 1 or 2 categorisation with a professional management plan and 10-year insurance-backed guarantee before they will lend.

Professional Treatment

A professionally prepared management plan from a specialist knotweed contractor, typically a member of the Property Care Association (PCA), is generally required to satisfy mortgage lenders and potential buyers. Treatment commonly involves herbicide application over multiple growing seasons (typically three to five years), with monitoring thereafter.

Property Passport UK allows property owners to store knotweed management plan documentation against their property record, ensuring this information is readily accessible for future buyers and their solicitors during conveyancing.