Should I Buy a House With Japanese Knotweed?

09 August 2018

If you discover that a property you are looking to buy is affected by Japanese knotweed or even that the next door property or land is affected, then you will want to think very carefully about whether you're prepared to take on the burden that comes with this.

The presence of Japanese knotweed can impact on how easy it will be for you to sell the property or even obtain a mortgage on it. Japanese knotweed is incredibly expensive and difficult to get rid of, it spreads quickly and could cause serious damage to your property. You will also have a legal responsibility to make sure the plant doesn't encroach on your neighbours' land.

What is Japanese Knotweed?

Japanese knotweed is a fast growing and hardy plant which can be incredibly invasive and can even grow through concrete, causing significant damage to land and buildings. The plant has stems thatcreep underground, exploiting existing faults or cracks in buildings, foundations and paving, making these worse as it continues to spread and grow.

The plant has heart-shaped leaves and strong, bamboo-like stems. More information and images of Japanese knotweed can be found on the website of the GB Non-Native Species Secretariat (NNSS).

How are Buyers Notified about Japanese Knotweed?

If a property that is being sold is known to be affected by Japanese knotweed, then this should be reflected in the asking price as it devalues a property. The seller also has a duty to disclose this information to the buyer when the property is marketed.

Whilst a lender's valuation report may not include an inspection of the garden and surrounding land,Chartered building surveyors are trained to recognise Japanese knotweed. So a building survey report should highlight any presence of the plant or advise if the garden is close to an area where the plant is likely to be found.Some lenders will not grant a mortgage on a property which has or is adjacent to land with Japanese knotweed whilst others will lend provided remedial action is being taken which is protected with guarantees and insurance.

TA6 Property Information Form - Japanese Knotweed

When someone sells their property, their Conveyancer will ask them to complete a TA6 Property Information form. The purpose of this form is to provide the buyer with important information about the property, so that they can make an informed decision as to whether they are happy to proceed with the purchase.

This comprehensive form asks the seller to provide detailed information, from council tax bands and utilities suppliers through to neighbour disputes and planning permission. The form also asks the seller to state whether the property is affected by Japanese knotweed.

Under this section of the form, it's noted that "Japanese knotweed is an invasive plant that can cause damage to property. It can take several years to eradicate." Sellers are then asked to confirm if the property is affected by Japanese knotweed (they can tick 'yes,' 'no,' or 'not known').

If they have answered yes, they are then prompted to confirm whether there is a Japanese knotweed management plan in place. If there is, then a copy of this plan should be included with the form when it's returned to the buyer's Conveyancer.

The purpose of this is to enable the buyer to decide whether or not they are willing to take on a property that is affected by Japanese knotweed. If the seller ticks no, and then it transpires that there is Japanese knotweed on the property that the seller knew about then the buyer could make a claim against them for damages, as the property will be worth less as a result.

There are a number of Conveyancing and environmental searches that have to be carried out when a property is bought or sold, but none of these searches currently address Japanese knotweed. For more information on property searches, see "What Property Searches Do I Need and Why?"

It's always a good idea for buyers to arrange for a comprehensive building survey to be carried out before committing to buying a new home. This is particularly important for anyone who is concerned that a property they're buying may be affected by Japanese knotweed.

What Can Be Done about Japanese Knotweed?

As the TA6 Property Information form highlights, Japanese knotweed is incredibly difficult to eradicate. It requires specialist treatment which can take years to fully take effect. This specialist treatment can be very expensive, with just a few square meters of Japanese knotweed costing up to £10,000 to treat, or even more if swift results are needed.

Most Japanese knotweed infestations will need to be treated with strong chemicals in order to be completely destroyed. Other treatments include digging out and disposing of the plant, but as roots can penetrate as deep as 7ft, often the plant will grow back again in which case this would need to be repeated year after year.

If the presence of Japanese knotweed is not affecting your enjoyment of the property or posing a risk to the structure of your home, you may wonder why it needs to be dealt with. Bear in mind that this plant is incredibly hardy and spreads fast. The more there is, the more difficult and expensive it could become to treat and it is unlikely that your costs to eradicate it or repair damage will be covered by your buildings insurance policy.

Legal Responsibilities for Japanese Knotweed

While it is not a legal offense for Japanese knotweed to be present on your own property, if this spreads into your neighbours land then you will be held responsible for this. Failure to deal with the issue could land you with a heavy fine.

Furthermore, it is a criminal offense to dispose of Japanese knotweed irresponsibly. Japanese knotweed is classed as 'controlled waste' meaning that it cannot simply be chucked in with other garden waste or thrown in the dustbin. Instead, a licenced waste carrier will need to be called upon to dispose of the plant correctly.

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