Japanese knotweed – what is the damage?

Japanese Knotweed is an invasive plant native to East Asia. In the UK there are countless properties affected by Japanese knotweed and the problems associated with this plant are considerable. One of the effects of having Japanese Knotweed on your property aside from the damage and disruption it can cause is that it could have an affect on the saleability of your property. Mortgage lenders are only prepared to provide mortgages to property buyers if the knotweed affected property has a Knotweed Management Plan (KMP) in place. For sellers who have Japanese knotweed on their property, trying to the sell the property at the normal value can be problematic and in some cases Japanese knotweed can devalue a property by a significant sum.

Japanese knotweed can cause damage to various parts of the property such as brickwork, cavity walls, sewage systems, fences, concrete slabs and driveways. Although Japanese Knotweed is unlikely to crack brickwork or concrete it will exploit a weak point and grow through it to get light and as it does this and matures it will expand the crack and cause more damage. Japanese knotweed can also have the potential to clog waterways and thus cause the risk of floods. Most importantly knotweed should not be built on. It can quite easily find a route to grow and appear indoors if there is a weak spot underneath or outside the new building. Japanese Knotweed can spread underground up to a maximum of 7 metres.

The main damages caused by Japanese knotweed:

Physical Damages

• Damage to the physical structure of the property

• Damage and possibly blockage to sewage systems

Non-Physical Damages

• Reduction in value of the property

• Difficulty selling the property

• Mortgage refusals

Identifying knotweed is sometimes difficult. The underground rhizomes grow laterally up to 7 metres from the main plant, but in the winter the main plant may not be visible. Fragments of rhizome can easily regrow and spread causing new plants to grow. If it spreads form one property to another there could be legal issues. Because of this it is important to manage Japanese knotweed to prevent further damage and spread.

If you do suspect Japanese knotweed on your property then it is important to seek professional help and advice on how to deal with it. Japanese Knotweed Ltd is the UK’s Largest Japanese Knotweed Company. Accredited by the Property Care Association (PCA) and the Contractors Health & Safety Assessment Scheme (CHAS), Japanese Knotweed Ltd provides the highest standards in Japanese Knotweed survey, damage assessment and treatment or excavation. Japanese Knotweed Ltd’s Knotweed Management Plan (KMP) is drafted in accordance to ‘The Knotweed Code of Practice’ accepted by mortgage lenders.