Question 1

What are the RICS Japanese knotweed categories?

Accepted Answer

The RICS 2022 professional standard "Japanese knotweed and residential property" uses a four-category management assessment (A to D). In broad terms: A is live knotweed within 7 m of a relevant structure and causing or likely to cause damage; B is live knotweed within 7 m but not causing damage; C is live knotweed more than 7 m away; and D covers a plant needing identification, or dead/treated knotweed with documented management. It replaced the older rigid 7 m "risk zone" approach with a focus on management and impact.

Question 2

Does the 7 metre rule still apply?

Accepted Answer

The 2022 RICS guidance moved away from treating 7 m as an automatic risk threshold, but 7 m remains a useful reference distance for proximity to a habitable space or relevant structure. The assessment now weighs distance together with whether the knotweed is live, whether it is causing damage, and whether it is being managed.

Question 3

Can I get a mortgage on a property with Japanese knotweed?

Accepted Answer

Often yes. Many lenders will lend where there is a treatment plan from a professional company backed by an insurance-backed guarantee (IBG), particularly for Category B. Category A (damage occurring) is more likely to affect lending and may require remediation. Each lender has its own policy, so the valuer's view and the management plan are key.

Question 4

What are my legal duties around Japanese knotweed?

Accepted Answer

It is not an offence to have Japanese knotweed on your land, but allowing it to spread onto neighbouring land can give rise to a private nuisance claim, and there are anti-social behaviour powers (community protection notices) for failing to control it. Under the Wildlife and Countryside Act 1981 it is an offence to plant or cause it to grow in the wild, and cut material/contaminated soil is controlled waste. Sellers must answer the TA6 knotweed question honestly.

Question 5

How is Japanese knotweed treated?

Accepted Answer

A PCA-accredited specialist will typically use a herbicide treatment programme over several seasons, excavation and removal, on-site burial/encapsulation, or a combination, set out in a management plan. Reputable plans come with an insurance-backed guarantee that satisfies most lenders. This tool does not specify treatment - it indicates the management category to inform that work.

Question 6

Is this a substitute for a specialist survey?

Accepted Answer

No. It is a screening aid that maps your observations to the RICS category framework. Positive identification, the definitive category and any treatment must come from a competent person - ideally a PCA-accredited Japanese knotweed specialist - and the current RICS professional standard governs the assessment in a survey.

Japanese Knotweed Category Tool

Site observations

Record findings and report on-site.

RICS 2022 management categories

Using this correctly

Frequently Asked Questions