This is one of the biggest questions being asked by homeowners in the UK – ‘how much does Japanese knotweed devalue property?’

Foremost, Japanese knotweed is the UK’s most invasive plant and it is dreaded for three key reasons;


The weed plant can cause great damage to your property if left unchecked. This includes the destruction of boundary fences, invasion of driveways, damage to the interior of the building, weakening of the house structures’ and damage to your garden all of which will require costly repairs.


Simply put, this weed plant does not stop growing. The root system can spread up to 7 metres wide and this is bad news for any homeowner because an infestation of the weed plant in their land will ultimately lead to reduced sizes of the land and depreciation of the land prices.


The weed plant can grow literally anywhere and it is extremely difficult to get rid of unless you use tried, tested and approved methods of eradication.

Knowing how much Japanese knotweed can devalue your house is key to retaining value in your property
Knowing how much Japanese knotweed can devalue your house is key to retaining value in your property

However, when it comes to property, this weed plant can greatly devalue your property if no proper treatment plan is put in place to eradicate it. The factors that determine how much Japanese knotweed can devalue your property are as discussed below:

The severity of the infestation

Frankly, the bigger the infestation of the Japanese knotweed within your property, the bigger the depreciation in property value you are likely to experience.

The reason for this is that it will be more costly to treat Japanese knotweed that is growing on a large scale as compared to an infestation that is just but minimal.

Equally, a large infestation often takes a long time to wipe out before a place can be said to be free of the Japanese knotweed, and the trickle-down effect of this is that investors may be discouraged from investing in the development of such property hence leading to the loss of value.


Proximity in this context refers to the distance between the Japanese knotweed infestation and the houses nearby.

Notably, the closer the infestation of the weed plant to a building, the more the value of such a building depreciates because of the fear that the weed will eventually damage parts of the building once there is contact and occasion the need for repairs which amounts to the usage of money.

On the other hand, if the weed plant is growing further away from the building, you can breathe a sigh of relief because the effect on the property in terms of its value can still be maintained at par with the current market price.


If a house is located in a high crime area, the presence of Japanese knotweed may not have adverse effects on the price because people may not ‘mind’ buying such a house and subject the weed plant to treatment until it is eradicated.

However, if the house is located in a rural setting, the presence of the weed plant will spell doom for the owner of the house because there is a great possibility that very few people can buy such a house unless it is sold at a rather discounted price.


More often than not, mortgage providers will be reluctant on lending to a person intending to use a house as security if it is identified to have Japanese knotweed.   The weed plant is categorized as a risk because of the significant damage it can cause to property.

This means that unless there is a proper management plan for the eradication of the weed, mortgage providers will not come to your assistance.

This factor may lead to depreciation of the value of the property as potential buyers may shy away from purchasing such a house owing to the risks involved.

Knowing how much Japanese knotweed can devalue your house is key to retaining value in your property
Knowing how much Japanese knotweed can devalue your house is key to retaining value in your property

What to do to ensure the value of your property does not depreciate

Insurance backed guarantee

You need to ensure that any treatment plan that you chose for the eradication of the weed plant has an insurance-backed guarantee that will cushion you from any future infestations of the weed plant under the same property.

A treatment program should cater for your short-term and long-term needs. Such an insurance guarantee will ensure that in the event you want to dispose of the property, its value remains intact as per the market price.

Make use of removal DIY methods

Some infestations of the weed plant may not necessarily require the services of professionals to get rid of them. For instance, smaller growths of the weed plant can be easily cut down and the roots are taken out of the soil as an eradication method or uprooted and burned.

Such removal DIY methods do not require the setting aside of costs to treat the weed plant hence can work a great deal not only in killing the weed plant but also in ensuring that the value of your property does not depreciate.

Seek compensation

In cases where it is evident that there was non-disclose by the seller, previous owner or surveyor under the sale agreement as the presence of Japanese knotweed in the property before a sale takes place, you can hold such people liable for their misrepresentation and acquire damages.

Compensation in this instance will help you manage the infestation until there is full eradication. Lying or failing to disclose the presence of Japanese knotweed by the relevant party under contract is dishonesty and you should make the most of such an opportunity.

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Knotweed can devalue your property the more it invades.


How much does Japanese knotweed devalue property?

Japanese knotweed invasion often strikes dread into the heart of homeowners because this weed plant can have a substantial impact on the value of houses. In reality, the depreciation in price can range from 10% to 80% depending on the severity and proximity of the Japanese knotweed.

Additionally, if as a homeowner you do not have house insurance, discovering this weed plant at a later time will lead to further added costs that may not be pocket-friendly. Simply put, the presence of Japanese knotweed on your property is a pain in the ass.

The root of this weed plant spreads fast and if they are not treated, they can block drains, damage the foundations of your property, weaken walls and all this adds to the misery of reducing the value of your house.

Want to know more about how much Japanese knotweed can devalue your property?

Knotweed Removal aims to provide the most up-to-date information, help and advice for YOU to make informed decisions. If you are unsure or uncertain about how to proceed, please reach out to us and we will gladly come back and advise you as best we can.

Governmental advice can be found here and the UK law covering the removal of Japanese Knotweed as stated under the Wildlife and Countryside Act 1981 can be found here.

The best means to contact us is via our email –

Do not forget we have a library of blogs covering many areas relevant to Japanese Knotweed, our free downloadable How-to Guides and Product Reviews on the latest methods being employed to eradicate or remove Japanese Knotweed.

Knotweed Removal, UK

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