Japanese Knotweed

Question 1

How would you identify Knotweed through the seasons

Answer 1

Spring:
Green leaves with a flat base and zig zag formation along the stems

Summer:
Budding white flowers

Autumn:
Brown leaves

Winter:
Black bare canes

Question 2

What are common defects caused by Knotweed

Answer 2

• Gardens destroyed
• Cracked underground drains in search for water
• Growth under patios leading to cracks
• Boundary and retaining walls
• Outbuildings

Question 3

What other common types of invasive species are there

Answer 3

Giant Hogweed

Question 4

What remediation works are there to treat Japanese Knotweed

Answer 4

Excavation of roots:
Involves the removal of rhizomes in order to prevent future growth

Burial/ encapsulation with membranes:
Involves a 5m barrier membrane which encapsulates the roots preventing growth

Chemical treatment:
Cost effective however will need multiple treatments and can be seen as temporary solution

Question 5

What impact on lenders is there from Knotweed

Answer 5

Can be difficult to secure a loan and insurers may be unable to provide cover

Question 6

How would you estimate the impact on value?

Answer 6

Seek specialist advice, there are knotweed websites that produce a rough figure of value

Question 7

What would you do if knotweed spread over Neighbouring boundaries

Answer 7

Setup a managment plan for the agreement of treatment works

If neighbours dont agree to works you will have to setup a policy where new owners agree to follow a continued treatment programme

Question 8

What guidance has RICS provided on Japanese Knotweed

Answer 8

Japanese Knotweed and Residential Property 1st Edition 2012

Question 9

What is the new approach to Japanese Knotweed outlined in the draft guidance note

Answer 9

More of a focus on management of the knotweed. The process utilises a decision tree, with detailed accompanying notes as an integral part of the assessment. This will place the property in a management category

Question 10

What is the seven meter rule?

Answer 10

A rule of thumb which states if knotweed is found 7 meters from the boundary line the chances of a mortgage being granted are low due to the risk

Question 11

What relief is available to those who spend money remediating certain contaminated or derelict sites, or those affected by Japanese Knotweed?

Answer 11

Land Remediation Relief (LRR) is a form of tax relief

Allows companies to claim up to 150% of the cost in cleaning up the site, against their Corporation Tax bill

Question 12

What are the penalties for ignoring Japanese Knotweed and allowing it to spread onto adjacent land?

Answer 12

• Criminal offence under the Wildlife and Countryside Act 1981. Magistrates court can impose a maximum fine of £5,000 or a maximum prison sentence of six months, or both. Crown Court can impose an unlimited fine or a maximum prison sentence of two years, or both
• Local authorities can grant a Community Protection Notice (CPN) and fines of up to £2,500 per person (£20,000 for an organisation)

Question 13

What did the landmark Japanese Knotweed case of Williams v Network Rail Infrastructure Ltd 2018 find?

Answer 13

Network Rail was liable for the cost of treating the invasive plant plus damages for the loss of use and enjoyment of their neighbour’s property (but not the reduced value of the property

Question 14

What did the House of Commons Science and Technology Committee report in May 2019 say about Japanese Knotweed?

Answer 14

• Physical damage to property from Japanese Knotweed is no greater than that of other disruptive plants
• Encouraged an evidence-based approach to ensure that the response is proportionate to the physical effects of the plant in the built environment

• Recommended that Defra commission a study on international approaches to Japanese Knotweed