5% of houses in the UK are affected by Japanese knotweed

5% of houses in the UK are affected by Japanese knotweed


This figure has jumped up hugely in recent years – with the exponential growth of Japanese knotweed (JK) this means 1 house in 20 could be reduced in value by up to £100,000!

The number of sites effected by Japanese knotweed in the UK.

At one of the CPD events we run for surveyors, an experienced gentleman stated that he had never come across JK on any property he had surveyed – this really blew us away as we see it every day. It really highlights the problem that many professionals cannot identify JK. The most common places it can be found are on brownfield sites and areas where fly tipping has occurred. Another common place is at the back of terraced houses and where there are badgers and foxes regularly travelling through a person’s garden.

The reason why we see a much higher concentration of JK in these areas is due to the way it reproduces. In the UK the seed is not viable, so although it produces seeds these will not produce viable plants. The plants therefore reproduce from cuttings. There are two types of cutting to propagate a new plant; a stem and a rhizome cutting. The stem has to have two nodules, one to become the root and one to become the new shoot. However, if a small piece of the rhizome is taken – and this can be as small as your fingernail – this will produce a new plant. For these reasons we would never recommend strimming JK or trying to excavate it by yourself as is can be very easily spread

Viable Japanese knotweed with typical internal orange colouring.

If, as a member of the public, you spread JK you can face a £2,000 fine and, if you are a business, it can be a £20,000 fine with 6 months in prison. Also, if you allow the JK to grow from your garden into a neighbour’s garden then they can bring a civil case against you for depreciation of the house, loss of enjoyment and even stress! Claims in excess of £30,000 are not uncommon.

Surveyors are the most common professionals to be litigated against if the JK has not been identified within their survey. With typical devaluations being 10% of the value of the property, this can cause a massive problem when trying to sell your house if you do not have the right people on board to assist you.

Here at Japanese Knotweed Expert we have been working with mortgage lenders, surveyors and solicitors for over two decades and are one of the foremost experts, that are commercially minded, within our field. So, if you require any advice or help then please do get in touch.