Invasive plant Japanese knotweed will no longer be taken into the same account in house valuations in new rules for surveryors from March 2022.
The Royal Institution for Chartered Surveyors (RICS) has published new guidelines for members.
The previous guidance for surveyors stated that the plant being present within seven metres of a property could slash 15 per cent of its value following the official survey.
The seven-metre rule has been now scrapped and surveyors are now able to use their discretion more freely when assessing the impact of knotweed infestations.
Nic Seal, founder and MD of invasive plant specialist Environet UK says: “The new Guidance Note is cautious and sensible, recognising the very real risk Japanese knotweed poses to homeowners and lenders, and giving greater clarity to surveyors.
“The blunt ‘7 metre rule’ has rightly been scrapped in favour of a more nuanced approach that allows surveyors to use their own professional judgement in determining the potential impact of Japanese knotweed.
"I’m pleased to see the focus is no longer only on the structure of the property and the risk of damage, which is rare, but also on amenity value – in other words, the effect of knotweed on the use and enjoyment of the garden.
“Equally importantly, it also recognises the problems that can result from encroachment of knotweed from adjoining land, requiring surveyors to flag infestations within 3 metres of the boundary on neighbouring properties.
Nic goes on: “If there’s any criticism, it would be that the Guidance Note suggests control of knotweed may be a more appropriate goal than eradication. While herbicide treatment can be an effective approach in certain cases, there are often very good reasons to make eradication the goal – and by settling for ‘control’ the bar is lowered for the sake of a lower initial cost.
"Herbicide treatment is particularly inappropriate where the plant’s location could impact neighbouring properties and be subject to potential legal claims, or on more valuable properties where the diminution of value justifies the higher cost of removal.”
In their official guidance, RICS says: "Japanese knotweed is a hardy bamboo-like deciduous perennial plant that grows quickly and strongly, spreading through its underground rhizomes or shoots, and thick clumps or standscan quickly grow to a height of over 2m during the spring and summer."
Since it was introduced, it has become a problem for buildings as it has been suspected of causing structural damage due to its strength.
In its new guidance, RICS says: "Japanese knotweed is certainly a challenging issue, but the reality does not mirror commonpublic perception."
