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Japanese Knotweed: problem or exaggeration?

  1. 26 July 2018
  2. By Andi Michael

Japanese knotweed has long been considered a problem when it comes to buying and selling properties. If found, the sturdy weed can lower the value of the property and make mortgage lenders hesitant.


Removing Japanese knotweed can be difficult – it needs to be consistently treated, and if your property has ever had a knotweed infestation, you need to acknowledge this when selling, and provide proof of the treatment.

Japanese knotweed has been in the news a lot recently, with the news that Network Rail lost a recent court case taken by property owners who believed they had been affected by knotweed from the rail tracks. This case sets precedence for a likely many more cases in future.

However, in an interesting twist, new research has been released suggesting that Japanese knotweed is not as harmful as it has always seemed. 

The research, conducted by the University of Leeds and infrastructure firm AECOM found no evidence that Japanese knotweed causes significant structural damage, and suggested that more damaging plans included trees, climbers and other shrubs. 

As such, mortgage lenders are being encouraged to reassess their lending policies when it comes to Japanese knotweed. The study found that the plan still had a negative impact when it came to flood risks and biodiversity, but it is less of a concern when it comes to buildings. The argument from the researchers is that Japanese knotweed exacerbates existing defects or weaknesses, but does not cause them.

We believe many surveyors are also of the opinion that Japanese knotweed is not as much of a problem as its reputation would have us believe.

If you are considering buying a property with Japanese knotweed, ensure you have proof of treatment and chat to a Chartered Surveyor, along with your mortgage lender.

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