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Forget me knot? New guidance gives hope to those affected by Japanese knotweed

Posted: 08/10/2021

RICS, working with the Housing, Communities and Local Government (HCLG) Select Committee and DEFRA, has produced a draft guidance note on Japanese knotweed and its impact on residential property. The new draft guidance is intended to create confidence that the presence of knotweed does not need to be a death sentence for home sales.

It is estimated that around 1.45 million homes in the UK are affected by Japanese knotweed. Affected properties can have their value significantly impacted, which can make it difficult for homeowners to sell their property or obtain a mortgage or insurance. However, RICS has advised that the terminal effect on sales is primarily due to incorrect information about the weed and its disruptive capabilities combined with a lack of awareness of the effectiveness of remediation options.

The new draft guidance intends to reduce the impact of Japanese knotweed by establishing a straightforward management framework for surveyors carrying out assessments. It gives advice to enable house sales to progress at properties where the presence of knotweed has been identified. The guidance will also set out a classification system to flag the most serious instances of knotweed infestation.

This draft guidance was issued for consultation at the end of June 2021 and the consultation period ended on 3 August 2021. The draft guidance can be found on the RICS website. The final version of the report is intended to be issued later this year and will replace the information paper titled Japanese Knotweed and Residential Property published in March 2012.

What is Japanese knotweed?

Japanese knotweed falls within the category of invasive non-native (or alien) species (INNS). These are plants or animals that are introduced into a natural environment where they are not normally found with significant negative consequences for their new environment.

INNS can limit biodiversity in an ecosystem by outcompeting, crowding out and displacing native species of plants and animals. Japanese knotweed has been found to cause structural damage to buildings and developed land including growing through tarmac and other surfaces, and even contribute to the risk of flooding through riverbank erosion. In addition to the impact on property values, the risk of damage can result in significant delays and cost implications for development projects.

Once identified, eradication of Japanese knotweed is very difficult, as the weed is resilient and regrows vigorously after being cut down. The roots drill deep into the soil and the speed of infestation means that even if only a small amount of roots are present the growth is likely to be significant.

What is the current legal position?

The pervasive and potentially destructive nature of Japanese knotweed has already caused the weed to be addressed in law.

Whilst it is not illegal to have Japanese knotweed present at your private property, the Wildlife and Countryside Act 1981 provides that it is an offence to cause Japanese knotweed to grow in the wild. There is, however, a degree of protection provided by the same statute which confirms that if it can be demonstrated that a person took all reasonable steps and exercised all due diligence to avoid committing an offence this shall be considered a valid defence.

Further, the Anti-Social Behaviour, Crime and Policing Act 2014 provides that enforcement action may be taken if a non-native plant has a detrimental effect of a persistent or continuing nature on the quality of life of those in the locality. This is likely if growth is left unchecked and the plant spreads beyond an individual’s property.

Notwithstanding that private growth is not prohibited, a property owner is required by law to disclose to any prospective purchaser the presence of Japanese knotweed and provide a management plan for eradication by a professional entity where it is present. Further, as Japanese knotweed is classified as controlled waste under the Environmental Protection Act 1990, disposal must take place at licensed landfill sites.

Control, not eradicate

RICS is optimistic the presence of Japanese knotweed does not need to result in property sales being delayed or cancelled in most cases if it is properly managed. The RICS guidance now places greater emphasis on the proper control of Japanese knotweed and not its eradication.  

RICS wants to promote the use of Japanese knotweed management plans to allow sales and developments to proceed. These will:

  • be comprehensive and issued by recognised contractors;
  • be assignable to subsequent owners;
  • relate to the whole of the property [not merely the affected area]; and
  • be backed by 5 to 10-year guarantees with third party insurance.

Such plans will also contain proposals as to what should be done in the event of some inevitable regrowth.

This latest guidance is being welcomed by the property industry. However, if you identify or suspect that Japanese knotweed is present at one of your properties, we recommend you seek expert advice before carrying out any action to ensure that the appropriate steps are taken.

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