UK's leading independent
Invasive Species advisor

Property Care Association’s only
approved independent surveyor

Ashfield Japanese Knotweed (AJK)  has extensive experience working with commercial and industrial property developers, high street banks, public authorities and industrial fund owners.

See a selection of our case studies below.

Portfolio Assessment

Given the increase in claims of Japanese knotweed (knotweed) encroachment and commercial investors, especially institution investors, are deterred from purchasing properties affected by knotweed, it is prudent for property portfolio holders to understand the risk presented by non-native invasive species (INNS).  Richard Newis of AJK has undertaken pre-acquisition due diligence reporting on behalf of some of the UK’s largest property portfolio holders and reviewed the risk to existing assets, from single sites, through to significant property portfolios such as Translink and Ulster Bus in Northern Ireland.

We recently undertook a desk study on 26 properties, on behalf of a Housing Association, and identified 9 of the 26 properties should be surveyed for knotweed.  This is a relatively high percentage for a property portfolio, as typically we see a range of 4% to 7% of properties requiring further investigation.  On surveying the site we will identify which properties are impacted and of those properties which are encroaching onto third party land; where encroachment is from third party land; and where encroachment would be difficult to prove both for the client and third party landowner.  Given that AJK is seeing claims of between £40k and £80k for cases of encroachment, should 9 of the client’s properties be impacted by knotweed and it can be demonstrated by neighbours (potentially three claims per property impacted) that encroachment is from the client’s land, the potential cumulative damages are significant, potentially business ending.  If you manage a property portfolio and want to discuss our services further please feel free to give Richard a call. Continue Reading

Knotweed Encroachment

In recent years there has been a significant increase in claims for Japanese knotweed (knotweed) encroachment onto domestic properties and Richard Newis of AJK has provided expert witnesses reports to court, typically on behalf of defendants.  In the majority of cases we have encountered the claims of encroachment has been based on tenuous evidence, such as a recent project in West Wales.  The contractor advising the claimant had asserted that knotweed had encroached from the defendants land and based on this assertion the claimant employed the services of a solicitor to pursue a claim of over £40,000.  On undertaking a desk study of the impacted area and surveying both properties, it became apparent to AJK that the contractor’s assertions were based on little evidence and we provided our client with a comprehensive report to defend the claim.  Two weeks later our client was advised by the claimant’s solicitors that the claim would no longer be pursued.  If you are defending a claim of knotweed encroachment or misrepresentation during a property sale, which you believe to be incorrect, please feel free to contact AJK for advice.

Continue Reading

Commercial Development – Norfolk

Sector: Commercial Development

Key Services: Survey, Tender Exercise & Project Management


  • Undertook a survey of the site for the extent of Japanese knotweed.
  • Reviewed existing geo-environmental reporting and identified the risk of Naturally Occurring Radioactive Material (NORM).
  • Submitted a Japanese Knotweed Management Plan to discharge planning conditions.
  • Procured and supervised contractor in the excavation of knotweed & coincidental NORM.


  • Works undertaken on time and within budget.
  • Works approved by both the Local Planning Authority and Radiological Protection Supervisor
  Continue Reading

Housing Development – Wrexham

Sector: Housing

Key Services: Survey & Contract Management


  • Conducted a survey of the site for invasive species.
  • Prepared alternative strategies to those presented by a specialist contractor.
  • Tendered the client’s preferred strategy to six specialist contractors.
  • Successfully negotiated planning approval of preferred strategy.


  • Saving of over £100k to the Client.
  • Works undertaken on programme and within budget.
  • Local planning authority approval.
Continue Reading

Site Acquisition – Bristol

Sector: Commercial Key Services: Survey & Risk Overview Report Actions:
  • Conducted a survey of the site for invasive species.
  • Identified additional risks to managing the identified Japanese Knotweed i.e. land contamination.
  • Reviewed Client’s aspirations for the site if purchased from the vendor.
  • Provided a fully costed Risk Overview Report on the site for managing the Japanese Knotweed identified.
  • Client understood the required works to manage the Japanese Knotweed prior to purchasing the site.
  • Client understood the commercial risk (£200k – £300k) prior to agreeing the purchase price for the site.
Continue Reading

Professional advice on control, treatment and removal

Providing value and effective management solutions