What is Japanese knotweed and what problems does it cause?

Japanese knotweed is a highly invasive non-native plant that is spreading throughout the UK at an alarming rate. It causes damage to buildings, creates legal disputes between neighbours and can prevent the sale of residential property.

As a result the Royal Institute of Chartered Surveyors (RICS) have published an Information Paper IP27/2012 titled “Japanese Knotweed and Residential Property”. This alerts surveyors to the problems that knotweed can cause, and lays down a framework for evaluating and mitigating the risks. The majority of mortgage lenders have now set policies relating to lending on knotweed affected property. They generally will require a detailed Japanese Knotweed Management Plan to have been prepared and put into action by a reputable specialist and be backed by suitable insurance backed guarantees before lending can be released and a house sale proceeds.

Disclosure of Japanese knotweed

The Law Society has amended its standard Property Information Form TA6 used by solicitors to include a section on Japanese knotweed. Failure not to disclose material information can lead to legal claims for misrepresentation. Relevant information is obtained from the vendor/owner in order to get a better understanding of the history of the knotweed on site. For example information on previous treatments, concealment, encroachment all help to determine the true scale of the knotweed infestation.

Without a sound understanding of these issues in relation to the property under consideration a suitable Management Plan cannot be prepared. In most circumstances, a site survey will only be commissioned where the presence of knotweed on a property or in adjoining land has already been identified, in order to inform a Japanese knotweed Management Plan. It is not unusual however, for buyers to commission surveys to rule out the presence of knotweed, particularly in areas considered to be at a high risk of infestation, such as land bordering railway lines.

The Site Survey

A survey of the property is carried out to look for any visible presence of Japanese knotweed. This includes visible growth, cut canes, dead canes and crowns on the surface of the ground. No intrusive investigation of the soil is undertaken unless specifically instructed. Where possible we also look at adjoining land outside of our client’s ownership. The scope of the assessment is identified on a plan within the body of the accompanying report/JKMP.

Where no knotweed is identified, a survey report is drawn up to include the extent of the investigation, the RICS categorisation and other useful information regarding Japanese knotweed in general. The report will not state categorically that no knotweed is present, only that none could be identified at the time of the survey, taking into account any information given to us by the property owner.

Where knotweed is identified on the property, or in adjoining land where it is within 7m of the subject building, the site survey will assess the following aspects which will be recorded in the JKMP and inform our recommendations:

  • The full extent of the knotweed including its rhizome system
  • The likely source or origin of the knotweed
  • The status of the knotweed in relation to its maturity, whether active or dormant
  • The location in relation to knotweed encroachment issues with adjoining land
  • Whether the building has possibly been damaged by knotweed
  • Site specific conditions that might influence the treatment methodology

Japanese Knotweed Management Plan

Japanese knotweed infestations vary considerably from property to property for a multitude of reasons. Origin, maturity, extent, location, growth state and site conditions all play a part in determining the best course of action for treating Japanese knotweed. The JKMP will clearly highlight the required work to treat or remove the knotweed, and the costs involved. Our experienced team will ensure the very best solution for your situation.

Armed with the full facts you will now know which way to proceed. You will be able to check that your lender is happy with the proposals. Instruct us to carry out the work and we’ll do the rest. We will issue you with a guarantee, insurance backed at Lloyd's, so you can rest assured that the knotweed problem is solved.

What is the Cost?

There is a small fee to prepare a property specific Japanese Knotweed Management Plan as this takes a considerable amount of expertise and time. It will highlight the most appropriate Japanese knotweed solution and the costs involved. We encourage you to be present during the on-site survey so that we can discuss the issues together.

To book a survey, please get in touch or request a call back today