Heide’s Blog, 26th October 2018

This week I came across my first case of Japanese Knotweed which had been picked up in a survey on a property.   The buyer had withdrawn their offer on the property and the vendor instigated their own independent report.

Japanese Knotweed is the most invasive plant known in the UK and it can cause major problems to property.


It can grow up to 7 metres in height and it can push through walls, block drains and lift patios if not treated.

Japanese Knotweed Damage

The known presence of Japanese Knotweed in the vicinity of your property (even it it’s further than 7 metres from the building or even on a neighbouring property) can affect the valuation.  Some lenders may refuse to lend if there is any sign of the plant, whereas others will take a view on it.  Usually dependent on the results of a specialist report.

Generally the Japanese Knotweed will need to be successfully treated or removed (with proof of responsible off-site disposal and a 10 year guarantee for the works).

The cost of either local herbicidal treatment or off-site removal will vary, as will the time taken for the results to be effective.

Some lenders will expect you to retain savings for future treatment in case of possible recurrences.

An article in “Mortgage Solutions” in September 2018 indicates between 4% and 5% of houses in the UK are directly or indirectly affected by Japanese Knotweed (see the article HERE).

Furthermore, the article says 850,000 – 900,000 properties have experienced a reduction in value of 10% due to its presence.

By law, vendors must disclose to potential buyers that the property has experienced problems with Japanese Knotweed and this information itself can act as a deterrent to buyers.

Japanese Knotweed originates from volcanoes in Japan and it’s hardy enough to grow up to 10cm in a day.  It takes light and nutrients from other plants which often kills them in its wake.

Knowingly allowing Japanese Knotweed to grow to a neighbouring property can result in a fine of £2,500.

April to October is the main season for the growth of Japanese Knotweed but mild winters have extended the growth period from March to November.

HERE is the link to an independent website which contains videos to show you how to identify signs of the plant.


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Heide’s Blog, 26th October 2018


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