RICS publishes guide to Japanese knotweed on residential property

The presence of Japanese knotweed on property can cause physical damage to buildings and structures (including drains, outbuildings, boundary walls and drives) and can be expensive and time-consuming to treat or remove. It also affects the value of the property, its marketability and insurability. 

In March 2012, the Royal Institution of Chartered Surveyors (RICS) published an information paper entitled Japanese Knotweed and residential property. (Please note that the information paper is only available to RICS members.) 

According to the information paper, most lenders are reluctant to lend on residential properties affected by Japanese knotweed. Those that are willing to lend will usually only do so after remediation works have been carried out. Most building insurance policies do not cover damage caused by Japanese knotweed. This puts buyers and sellers in a difficult position if a lender refuses to lend unless the buyer has obtained building insurance that covers Japanese knotweed. 

The purpose of the information paper is to set out a methodology for assessing the risks and quantifying the costs associated with Japanese knotweed on residential property, in an objective and consistent manner, when carrying out valuations and surveys. This should then enable lenders, insurers, buyers and homeowners to make more informed decisions. 

The information paper explains:

  • Why Japanese knotweed is a problem.
  • How it can damage residential property.
  • The various options for dealing with Japanese knotweed.               

According to RICS, most Japanese knotweed infestations are not as severe or as costly as many people (including lenders) think. Having a standardised approach to assessing the risks and costs should enable Japanese knotweed to be dealt with as just one of many factors that needs to be taken into account when valuing a residential property, as opposed to it being a "deal breaker". 

There is no legal obligation on a seller to disclose information about Japanese knotweed so it is up to the buyer to raise the necessary enquiries and carry out appropriate investigations. The information paper indicates that if a client wants greater assurance, they should commission a HomeBuyer Report or a building survey. Although these are not specifically aimed at investigating Japanese knotweed, they provide a more comprehensive investigation than a mortgage valuation inspection.

This information is intended as a general discussion surrounding the topics covered and is for guidance purposes only. It does not constitute legal advice and should not be regarded as a substitute for taking legal advice. DWF is not responsible for any activity undertaken based on this information.