Japanese knotweed may not be 'death sentence' for Ipswich homes

Japanese knotweed can be identified by its thick red stem and large heart-shaped leaves. Picture: EN

Japanese knotweed can be identified by its thick red stem and large heart-shaped leaves. Picture: ENVIRONET UK - Credit: Archant

Japanese knotweed may not be as big a threat to properties as previously feared, according to building experts.

The invasive species has been a fear of homeowners and prospective buyers for years, with research suggesting it could break through concrete structures as it continues to grow.

Ipswich is known to have the highest number of infestations in Suffolk, with data this year showing 41 recorded within a 4km radius.

The plant grows aggressively and can break through cracks in concrete or brickwork

The plant grows aggressively and can break through existing cracks in concrete or brickwork - Credit: Allcott Associates

Overall, the number of properties affected in the UK is estimated to stand at 1.45million, knocking as much as a tenth off house prices.

Those initial thoughts over its dangers may not be correct, however, according to a draft report by the Royal Institution of Chartered Surveyors (RICS).

The RICS updated its guidance last month, with report author Philip Santo saying it is not a "death sentence" for home sales.

The report quotes studies arguing it is "impossible" for the plant to grow through intact concrete, and instead only poses a danger through pre-existing cracks in brickwork and concrete.

It adds that "substantial" structures are "rarely" damaged by the plant.

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The RICS is instead working with the government and DEFRA to establish a management framework to ensure sales of affected properties can proceed, using a colour system to flag the worst cases.

The plant can be identified by its shovel-shaped leaves, which grow in a zig–zag pattern from bamboo-like stems

The plant's leaves grow in a zig–zag pattern from bamboo-like stems - Credit: Allcott Associates

Mr Santo said: "Creating confidence and awareness that knotweed isn’t a death sentence for home sales is a key principle behind this guidance – it’s certainly not the ‘bogey plant’ that some make it out to be."

The plant still grows aggressively however, and a legal obligation remains for affected homeowners to prevent it spreading to the wild or neighbouring properties. They must also declare it to prospective buyers.

A consultation into the report ends on August 3.

One firm helping to guide those affected, Allcott Associates Chartered Surveyors, has welcomed the shift from RICS but encouraged people in Ipswich to be on the look-out for the plant.

Tim Allcott, partner at the firm, said: “It is very hard to spot in winter because it dies back almost completely.

"Its rapid growth during the warmer, lighter months means that it becomes more obvious, even if it has previously been cut back. So, spring and summer present a great opportunity to identify any infestations."

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