Updated November 2026 to reflect current legislation and Government guidance.
Japanese Knotweed (scientific name Fallopia japonica) is native to Japan, Korea and parts of East Asia and China. It is a highly aggressive invasive plant that can damage external walls, foundations, grounds and drains. The Japanese Knotweed has the ability to grow up to 20cm per day, 3 metres deep into the ground and spread 7 metres in all directions.
The Environmental Protection Act 1990 designates Japanese Knotweed controlled soil as controlled waste, meaning that only a licensed contractor and licensed disposal facility can be used during its removal and disposal.
It is important to recognise that standard pre-purchase Survey and Valuation reports are not focused on the identification of the invasive plant species. If a Surveyor suspects the presence of Japanese Knotweed, this will be mentioned in the report. However, a specialist investigation by a qualified Japanese Knotweed surveyor will be needed to confirm it. In this case, it will also be prudent to request for a Japanese Knotweed Management Plan (JKMP), any guarantees and warranties in this regard. We recommend that all specialist investigations and documentation is requested prior to your legal commitment to purchase.
In 2022, the Royal Institution of Chartered Surveyors published Japanese knotweed and residential property (1st edition), which is now an RICS professional standard. It can be accessed on: Japanese knotweed and residential property.
The RICS Professional Standards states that “…research has demonstrated, and it is now generally accepted, that Japanese knotweed, poses little or no risk of structural damage to robust buildings with substantial foundations such as dwellings, as opposed to less sturdy structures with shallow foundations, such as conservatories, garages or boundary walls. The so-called ‘7m rule’ focused more on what has been demonstrated to be an overstated risk of Japanese knotweed to buildings, rather than its sometimes-serious impact on amenity…”
Does Japanese Knotweed Affect The Mortgage?
The presence of Japanese Knotweed does not automatically warrant for the refusal of a mortgage offer, provided it is controlled and maintained. Different lenders have a different approach when it comes to assessing mortgage applications. Some lenders will lend as long as there is an eradication plan in place, while others may refuse the application if Japanese Knotweed is found on or within vicinity of the property.
Legal Implications of Japanese Knotweed
It is not a crime to have Japanese Knotweed present on your property. However, it is listed in Part II of Schedule 9 to the Wildlife and Countryside Act 1981. Under section 14(2), it is an offence in England and Wales to plant it or otherwise cause it to grow in the wild.
This can include spreading the plant through cut stems, soil or other material containing it. Japanese Knotweed waste must also be disposed of correctly, as explained above.
Allowing Japanese Knotweed to spread onto a neighbour’s land is not a criminal offence in itself. However, it can be a private nuisance, and the neighbour may be able to bring a civil claim for damages.
Where it is having a detrimental effect on the local community, the council can also issue a Community Protection Notice under the Anti-social Behaviour, Crime and Policing Act 2014. Failing to comply with a notice is an offence.
Methods To Control/Eradicate Japanese Knotweed
- Chemical Control: It usually takes at least three to four seasons to eradicate Japanese knotweed using weedkiller. Professional contractors, however, will have access to more powerful weedkiller that may reduce this period.
- Specialist Contractor: Digging-out the deeply penetrating plant, with rhizome which has a potential to spread around 7 meters of its roots, which can be extracted and disposed of by a licensed Contractor.
- Burning: In England, Japanese Knotweed can be burnt on the site where it was removed, once it is dry. You will usually need a waste exemption (D7, burning waste in the open), must follow local byelaws and must not cause a nuisance. If you are an individual, check with your local council first. Any ash or remaining plant material buried on site must meet the Environment Agency’s RPS 178 conditions.
- Using professional companies: Royal Institution of Chartered Surveyors (RICS) has worked with the Property Care Association (PCA) to establish the PCA Invasive Weed Control Group (IWCG) trade body for Japanese knotweed specialists, which provides a register of vetted consultants and contractors. These experts will provide an expert report, outlining the location of the plant, risks involved with suggested treatment plans. This report can be used for mortgage purposes and its commission is insurance-backed.
Further reading and guidance around on the Japanese Knotweed can be found on GOV.UK website – How to stop invasive non-native plants from spreading.
When K&A Surveyors are instructed to undertake a Building Survey or Homebuyers Report, we will inspect the property and provide you with advice in relation to any Japanese knotweed we may find.
We also see this on many commercial premises when preparing Schedules of Dilapidations for the freeholder and negotiating Dilapidations for the Leaseholders.
If we can be of assistance on any of the above then please do not hesitate to contact us.