Japanese knotweed remains one of the most concerning issues in the UK property industry as recent research suggests that this highly invasive plant has wiped an estimated £21.4 billion from the value of the UK housing market. The legal and financial implications associated with its presence has caused widespread concern in the conveyancing world, leading to issues surrounding the value, mortgageability and future saleability of a properties. Although Japanese knotweed is now better understood than it once was, the presence of the plant can still cause delays and complications during the conveyancing process if not dealt with timely and efficiently.

What Is Japanese Knotweed, and how can it be identified?

Japanese knotweed is a plant species which typically appears with bamboo-like stems, heart-shaped green leaves and small white flowers during late summer. The plant is known for its extremely rapid growth, strong underground root systems, difficult and costly removal and the ability to spread quickly if untreated. As a result, the Environmental Protection Act 1990 places responsibilities on landowners to prevent the spread of Japanese Knotweed into neighbouring land as well as their own, as the plant can cause issues to not just those who have it, but also those in the nearby vicinity. Examples of where Japanese knotweed can grow are: driveways, walls, pathways and drainage systems, as well as properties located near railway lines. These areas are well established for Japanese Knotweed as railways are surrounded by embankments, disturbed soils and restricted-access locations thus creating conditions that support the continued spread of the species. In the South West alone, areas such as Bristol, are deemed to be a ‘hotspot’ for the plant to grow, most likely due to the canal network and former industrial sites and allotments that are prevalent in the area.

Sellers’ Obligation to Disclose Japanese Knotweed

At the outset of a property sale, sellers are under a legal obligation to complete a Property Information Form (TA6) which makes specific reference to whether the property is affected by Japanese Knotweed. In the previous 4^th Edition of the Property Information Form, sellers were able to answer ‘Yes’, ‘No’ or ‘Not Known’. They were also asked whether there were management and a treatment plan in place and were requested to supply a copy with any insurance linked to the plan. In the new 6^th Edition of the Property Information, however, there is an additional question that asks whether a Japanese Knotweed survey has been carried out. Not only does this add a further layer of protection for buyers, but this also prompts sellers to undertake a survey if they are unsure as to whether the property is affected by the plant, as if answered incorrectly, could lead to issues further down the line. Providing full and transparent disclosure at the outset of the transaction is essential as failing to disclose Japanese knotweed could result in compensation claims following completion, legal disputes and ultimately financial losses. Therefore, transparency by the seller is vital as it can help minimise the risk of an abortive transaction and improve the chances of the transaction proceeding smoothly.

The Impact Japanese Knotweed Can Have on the Conveyancing Process

Mortgage Lenders – additional enquiries

One of the primary concerns surrounding Japanese knotweed relates to mortgages as many lenders have strict policies regarding properties affected by the plant. Therefore, ‘raising enquiries’ is an essential part of any solicitor’s role, as their aim is to protect the lender and ensuring their lending criteria is met. Lenders may require specialist surveys to confirm the extent of the infestation and often request evidence of an ongoing treatment programme, together with insurance-backed guarantees. In some cases, lenders may reduce the property valuation or, in more severe situations, refuse to lend altogether. This can create difficulties for buyers seeking mortgage finance and may ultimately result in buyers withdrawing from the purchase entirely. Although further enquiries can sometimes cause further delays, they remain essential in safeguarding lenders and buyers when understanding whether the ‘root’ of the issue has been resolved.

Surveys – identifying the problem

Surveyors play a crucial role in identifying signs of Japanese knotweed during inspections and will inform any potential purchasers as to its presence. Where evidence of the plant is identified, buyers are often advised to obtain a specialist invasive plant survey to assess the extent of the infestation, the potential risk to nearby structures and the appropriate method of treatment or management. These additional investigations can lead to increased costs and may result in further negotiations between the parties regarding responsibility for treatment expenses, retention agreements or, in some circumstances, a reduction in the agreed purchase price.

These investigations are essential however in circumstances where buyers require a mortgage. In recent research, properties affected by Japanese knotweed may experience a reduction in market value, with estimates commonly ranging between 5% and 15% depending on the severity of the infestation, the proximity of the plant to the property, and whether adequate remediation measures have been implemented. This may ultimately affect a buyer’s confidence in proceeding with the transaction, even where a professional treatment plan and insurance-backed guarantee are already in place. This is largely due to ongoing concerns surrounding future maintenance obligations, potential structural risks, and the impact on the property’s long-term marketability which can be recognised by obtaining a survey.

Whilst Japanese knotweed can present challenges during a conveyancing transaction, its presence does not necessarily mean that a sale or purchase cannot proceed. The key is to identify any issues as early as possible, ensure full and accurate disclosure, and obtain the appropriate professional advice and treatment where required. By taking a proactive approach, buyers, sellers, lenders and conveyancers can work together to manage the risks associated with Japanese knotweed and minimise delays. If you are buying or selling a property and have concerns about Japanese knotweed, seeking legal advice at an early stage can help ensure the transaction progresses as smoothly and efficiently as possible.

Next Steps: Get in touch

If you would like to discuss anything relating to the above then please don’t hesitate to reach out to our team of legal experts at John Hodge Solicitors, conveniently located throughout the South West, with offices in Bridgwater, Bristol, Clevedon, Wedmore, Weston-super-Mare and Yatton.

You can contact us either:

• by email
• via our website
• by calling us on 0800 097 8611