Problems caused by Japanese Knotweed

Japanese Knotweed Management in Ealing, Chiswick, Acton and Greater London


What are the problems caused by Japanese Knotweed?

Japanese knotweed is a non-native, invasive, resilient perennial plant. Japanese knotweed is also known as Fallopia Japonica or Reynoutria Japonica. It is listed in the top 100 most invasive plants in the world.


Structural damage

Japanese knotweed spreads via a root system (rhizomes) or by small fragments of the knotweed plant being deposited in other areas. Fragments as small as 0.7gram can grow to a mature new JK plant.

Fine rhizomes of Japanese Knotweed can penetrate small fractures in build structures eg; walls, patios, drives, foundations, tarmac, underground pipework etc. causing cracks and damage due to the pressure exerted by the expanding rhizome.

However, it is extremely unlikely for the damage to be ‘structural’ i.e. it is very unlikely to affect the stability of a building but may de-stabilise outbuildings with shallow/ weak foundations, freestanding walls etc. In search of moisture Japanese Knotweed rhizomes could damage and block underground drainage pipes, manholes and other structures.

Knotweed rhizome spread from the parent plant or crown, this could be in any direction underground. A mature knotweed crown can produce rhizomes of up to 7 meter in length, but the average spread is up to 1- 3 meters, and grow to a depth of 2m to 3meters.

APSL Japanese Knotweed Ltd. will take into account the risk of damage from Japanese Knotweed rhizome in their assessment of a property. This is based on criteria advised by the Royal Institute of Chartered Surveyors (RICS).

Impeding or preventing property sale / Refusal of mortgage or building insurance.

Mortgage lenders, banks, and building societies refuse lending against a property with Japanese Knotweed, We can help at APSL, our PCA approved Japanese Knotweed Management Plan together with a five or ten year insurance backed guarantee (IBG) is accepted and recognised by banks, mortgage lenders, building societies.

As a seller you need to declare the presence of knotweed on the Law Society Property Information Form TA6. In refusing to do so, a claim can be made against the seller under the law of misrepresentation.

Knotweed on neighbouring grounds.

You are allowed to have Japanese knotweed on your grounds unless a Community Protection Notice requires you to control it. If neighbouring knotweed growth is not controlled and starts to encroach on or towards your property, have a kind word with your neighbour and ask them to take knotweed control actions with a reputable company such as APSL Japanese Knotweed Ltd. People are often not aware that they have knotweed growth on their property.

If Japanese Knotweed on your property spreads into the wild this would contravene the Wildlife & Countryside Act 1981 (as amended). This could include allowing the plant to spread from your property into the neighbouring land by its rhizomes extending underground into the adjacent land, i.e. park, nature reserve, woodland etc. It is accepted that the distance Japanese Knotweed can spread underground is a maximum of 7m.

The Royal Institution of Chartered Surveyors (RICS) have updated their Japanese Knotweed risk table from March 23rd 2022, taking into account the real risk to a property and addresses some of the concerns of the lenders and insurance companies.

The RICS new 3-meter rule for Japanese knotweed;

Japanese knotweed can spread underground up to 7meters from the visible knotweed canes but spreads more typically up to 3 meters. Surveyors are advised to flag up the presence of Japanese knotweed on adjoining properties where it is within three meters of the boundary. If the surveyor identifies Japanese knotweed further than 3m beyond the property boundary, it does not need to be reported, however it is recommended that a note of the observation is made.

If your neighbours take no action after making them aware of their knotweed problem, you could offer to pay for the treatment, which often gives the quickest desirable result. However, if this all fails, local councils and the police have the power to issue Community Protection Notices, see our page on, the laws around Japanese knotweed.

If you are concerned that a plant on your property may be knotweed, you can send us a photo for identification via our photo identification link.


Japanese knotweed plant matter, including the soil of its buffer is classed as controlled waste and cannot be discarded in your garden waste or taken of site. It needs to be disposed of and taken to a licensed landfill site with the facilities to deal with knotweed. If you discard it elsewhere, you will breach the environmental protection Act.

Hazardous Waste; although Japanese Knotweed is not covered by this legislation specifically, it will change when knotweed is treated with certain residual herbicides, it will then change from controlled waste to hazardous waste and falls under the hazardous waste regulations 2005. Failure to abide by this legislation will lead to prosecution. See our page on, the laws around Japanese knotweed.

Loss of Biodiversity and aesthetic damage to gardens and landscapes

Japanese Knotweed out-competes other plant species and causes loss of biodiversity threatening native plant and animal species. It could encourage vermin as litter gets trapped in the dense clumps of Knotweed stands.

JK can cause flood risks and have other negative impacts on ecosystem surfaces.

In Europe, there is no “natural predator” to keep Japanese Knotweed under control, hence it needs to be treated as soon as possible to keep possible damage to your property and repair costs down.

Contact APSL Japanese Knotweed Ltd.
Click or drag files to this area to upload. You can upload up to 4 files.