The Science and Technology Committee called for lenders to take a more measured and evidence-based approach to the plant.

Japanese knotweed is wiping thousands of pounds off property values because mortgage lenders take an ‘overly cautious’ approach to the plant, according to MPs.

The Science and Technology Committee said the presence of Japanese knotweed could have a ‘chilling’ effect on the sale of a home, despite the physical damage it caused to properties being no greater than for other disruptive plans and trees.

Some lenders will not advance a mortgage on a property that has Japanese knotweed growing within seven metres of it, while others will only do so if the owner commits to funding a long-term treatment programme.

This approach is despite the fact that the Royal Institution of Chartered Surveyors, which put forward the so-called ‘seven metre rule’ in 2012, acknowledges that it is no longer current.

The committee called for lenders to take a more measured and evidence-based approach to the plant.

Norman Lamb, chair of the Science and Technology Committee, said:

“It is clear that the UK’s current approach to Japanese knotweed is more cautious than it needs to be, especially when comparing it to that of other countries.

“The current framework lacks a clear and comprehensive evidence base and yet is causing significant problems to some house vendors and purchasers.”

Why is this happening?

Japanese knotweed is a highly invasive, fast-growing plant, which was introduced to the UK in the mid-19th century.

It can cause structural damage to buildings, pushing through cavity walls and drains, and through asphalt and cracks in concrete.

It is very difficult to eradicate, and it is described by the Environment Agency as the UK’s “most aggressive, destructive and invasive plant”.

Who does it affect?

It is estimated that 2% of development sites and 1.25% of residential properties in Great Britain are affected by Japanese knotweed.

The committee said its investigation found the plant caused disrupted sales, diminished property values and extended legal processes.

People’s homes could be impacted even if the plant was on neighbouring land.

Research by the Crop Protection Association found that among 100 people affected by Japanese knotweed, 15% had a property deal fall through, 20% suffered a drop in the value of their home and 10% had to pay compensation or insurance claims.

What’s the background?

The report warned that the ‘seven-metre rule’ was being used as a blunt instrument, adding that the risk assessment framework put forward by RICS lacked a clear and comprehensive evidence base.

It added that a significant industry had built up around controlling Japanese knotweed, but lenders in other countries did not treat the plant with the same degree of caution.

It also called for mediation to be used to settle disputes relating to Japanese knotweed, rather than homeowners having to rely on expensive and time-consuming litigation.

The committee found that there was “surprisingly little academic research” about the physical effects of the plant on the built environment, and it welcomed the Environment Agency’s offer to approach other parties, including Defra, about filling this gap.

It also welcomed a commitment by RICS to update its 2-12 framework.

Top three takeaways

  • Japanese knotweed is wiping thousands of pounds off property values because mortgage lenders take an ‘overly cautious’ approach to the plant, according to MPs

  • Some lenders will not advance a mortgage on a property that has Japanese knotweed growing within seven metres of it, despite the physical damage it causes being no greater than for other disruptive plans

  • The Science and Technology Committee called for a more measured and evidence-based approach to be taken by lenders

You might also be interested in...

* DISQUS *
comments powered by Disqus