The Japanese knotweed damage has been an uninvited guest in the UK since the 1950s and, in its wake, has been spreading like wildfire all the way through gardens, and domestic and commercial settings with no remorse.

The ferocity of the Japanese knotweed damage is highly extensive to property, buildings, and gardens if not controlled at the early stages of its growth. To this end, the subsequent segment of this article will unravel the various forms of damage that Japanese knotweed can cause.

Japanese knotweed damage to property

The mere presence of the Japanese knotweed near a house is hazardous to the structure since the weed tends to exploit tiny places, especially around the joints and weak cracks, to penetrate through.

The effect of this marauding nature of the weed is that as the roots and rhizomes of the weed force their way through, the structure eventually weakens and will require constant repairs lest the building collapses in the long run.

Japanese knotweed damage to drainage pipes

Considering that just like any other plant, the Japanese knotweed needs moisture/water and sunlight.

This natural element makes the weed more treacherous in its quest to seek moisture. Therefore, where the Japanese knotweed is found growing in drainage pipes, it is highly likely to find that its roots and rhizomes have led to clogging, blocking, and even complete damage to such pipes.  

Notably, the Japanese knotweed damage is reserved for the drainage pipes and extends to other underground infrastructures ranging from water pipes, electrical underground cabling, etcetera.

Japanese knotweed damage to flora and fauna

While the Japanese knotweed damage is vastly on the ground, its effect above it cannot go unsaid.

Naturally, the aerial cover of this weed can become very dense and impenetrable while covering large pieces of land and impeding the natural growth of flora and fauna beneath the weeds. Hence, where the cover is very dense, it is safe to say such an area becomes wasted land.

Japanese knotweed in the garden can cause both damage and legal issues
Japanese knotweed in the garden can cause both damage and legal issues

Reduction of usable space

The dense growth of the Japanese knotweed can easily lead to reduced sizes of play areas or even gardens. The weed can grow up to 12 feet high and, as such, can become a menace when its leaves grow large.

This essentially means that property owners are in danger of losing the right to the enjoyment of peaceful, serene, and quiet property. 

If your house with Japanese knotweed is growing in excess it will cause damage to your property and potentially devalue it too
If your house with Japanese knotweed is growing in excess it will cause damage to your property and potentially devalue it too

Japanese knotweed damage to driveways, pathways, and patios

The weed can grow in between the spaces, forming paves and driveways.

Although the damage may not at first be extensive if left unattended, this may lead to the expansion of the joints of the concrete and eventually result in serious damage.

In extreme cases, the weed can completely block such facilities’ usage. There are various causes of the Japanese knotweed lifting asphalt; thus, we cannot undermine its damage.

Japanese knotweed damage to walls, boundaries, and fences

Considering that the Japanese knotweed, once fully grown especially from the ground up, can become very heavy, it can easily overwhelm lightweight garden walls and fences, especially where the foundations are not so strong or poorly constructed.  

Therefore, the mass and weight of the weed can lead to the sudden collapse of such weak walls and fences.

Can Japanese knotweed devalue my house - yes it can due to its invasiveness and the subsequent legal issues
Japanese knotweed damage can devalue your house due to its invasiveness and the subsequent legal issues

Japanese knotweed damage to property value

Normally, as a rule of thumb, the value of the property will appreciate based on the maintenance afforded to it and the nature of the surrounding environment, amongst other things.

However, studies show that in areas where the Japanese knotweed is vastly present, the value of the property in and around such an area greatly depreciates based on the invasive nature of the weed and the unprecedented damage that is likely to result.

Considerably, very few people will invest in a property that does not guarantee good serenity, peace, and quiet free of invasive weeds.

Noting that the weed is dangerous to both the building and the environment within, this aspect greatly contributes to the depreciation of property investments around an area affected by the weed.

Additionally, there are many emerging cases of mortgage lenders being overly reluctant to offer financial support to purchasers intending to buy such properties under the Japanese knotweed attack, which makes it extremely hard to buy or sell such houses.

Japanese knotweed damage on the interior of a building

Remarkably, the fact that the Japanese knotweed can creep through tiny spaces in between walls or even open spaces of a building leads to a greater problem of having to face the consequences of the weed inside the house.

The weed can ascent up the house walls, making the interior unpleasant and uninhabitable if not dealt with urgently. The weed has also been known to enter the chimneys of a house and climb outside, searching for sunlight.

This poses the danger of the chimney being completely blocked and inaccessible.

Walls and boundaries are susceptible to Japanese knotweed damage to buildings too
Walls and boundaries are susceptible to Japanese knotweed damage to buildings too

Japanese knotweed damage to biodiversity

The Japanese knotweed has been known to drive out native vegetation that has been in existence in a certain place due to its aggressive nature and dense cover once it becomes widespread in such an area.

This, in return, can lead to vast effects on the ecosystem of a place; for instance, the dense Japanese knotweed cover leads to the shedding of leaves of small plants, thus endangering their existence.

There are also cases where due to the Japanese knotweed in an area of large sizes, small streams have vanished.


The Japanese knotweed damage to property, buildings, gardens, and the natural environment has short-term and long-term effects that may be irreparable if not resolved at the earliest possible stage.

Importantly, the best way to do away with some of these damages is to constantly conduct repairs, especially to property, and also to take the necessary steps to eradicate the Japanese knotweed from the area of growth.

Want to know more about Japanese Knotweed damage?

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

Bestseller No. 1
Bayer Garden 2 x Path, Patio & Drive Weed Killer & Watering Can Set - 3 x 8g Sachets per pack treats upto 75sqm - Kills Ground Elder, Nettles, Docks, Couch Grass & Japanese Knotweed.
  • This exclusive twin pack and 9L Watering Set is everything you need for clearing weeds from paths, patios and rives including areas of tarmac, concrete and block paving.
  • Kills tough weeds and their roots including: Ground Elder, Nettles, Docks, Couch Grass, Japanese Knotweed, Brambles, Bracken & Ivy.
  • Each box contains 3 x 8g Simple ready measured soluble doses and treats up to 75sqm. Apply at any time when weeds are showing green leaf and are actively growing.
  • Sold with our durable 9L or 2 gallon capacity galvanised steel watering can with removable brass rose. Colour cannot be guaranteed. Watering can will be randomly picked and despatched.
  • Keep children and pets away from treated areas until the spray has dried.
Bestseller No. 2
Roundup Tree Stump Weedkiller, Super Concentrate 250 ml
  • Kills ivy japanese knotweed, saplings, brambles and nettles to the root
  • Kills up to 16 tree stumps
  • Contains a reusable pipette for specialist treatment of japanese knotweed
  • Kills the roots so weeds don't come back
  • Degraded in the soil by micro organisms
Bestseller No. 3
Weedol 011005 Pathclear Weedkiller Liquid Concentrate, 6 + 2 Tubes
  • Unique dual action fomulation, kills weeds to the root and prevents new weeds growing for up to 3 months
  • Ideal for paths, drives and patios
  • No measuring or mess - just add water
  • Creates an invisible barrier that prevents new weeds for up to 3 months
  • Children and pets need not be excluded from treated areas (once dry)
Bestseller No. 4
RootBlast - RootBlast 360 Glyphosate Home Garden Weedkiller - 1L Bottle with Integral Measuring Device Pair - Includes Pair Of gloves - 1L Makes Up to 50L
  • WEED KILLER CONCENTRATE: Rootblast's strong weed killer is both super-concentrated and tough on most broad leaf and grass weeds. It's specifically designed to bring you the best results by using systematic herbicide technology. It targets weeds from the inside and kills them at their underlying roots, preventing any future growth
  • GLYPHOSATE WEED KILLER: For optimal weed control, Rootblast have created a concentrate weed killer that contains 360g/l of glyphosate. Glyphosate is a broad-spectrum systemic herbicide and crop desiccant that is used by famers. It kills and destroys the weed without affecting the crop. By using glyphosate, Rootblast's weed killer is stronger and more effective than most other weed killers on the market
  • GLYPHOSATE HERBICIDE: This powerful and effective weed killer is designed to target weeds such as dandelion, grasses, docks, nettles, willowherb, bindweed, woody brambles, tree stumps, ivy and more. After applying Rootblast's heavy duty weed killer, the first signs of weed control are visible when the weed leaves yellow - this can take anywhere from a few days to up to 2-4 weeks. From this 1 litre bottle of glyphosate herbicide concentrate, you can make up 50 litres of product when it's diluted
  • DOCK, GRASS & DANDELION KILLER: Alongside this industrial strength weed killer, you'll receive a pair of protective gloves as well as the integral measuring device attached to the bottle. The gloves provide you with protection to ensure your experience is as easy and safe as possible. The integral measuring device is an inbuilt measuring cup, simply remove cap and carefully squeeze the container until the cup is full
  • TOTAL PROTECT WEED GARDEN SPRAY: This easy to use product is available as a ready to use tough, concentrated weed killer that comes with a integral measuring device attached and protective gloves. Use by professional garden and farmers, this product can tackle your weed problem and kill the weed from the root - the ultimate weed killer!
Bestseller No. 5
Rootblast Glyphosate Weedkiller 4 x 100ml Concentrate with 5L Pump Sprayer
  • For use on unwanted vegetation and areas not intended to bear vegetation
  • Contains 72 g/l glyphosate for effective control of annual and deep-rooted perennial garden weeds, including grasses*, docks, nettles, willowherb, dandelion and bindweed. Also suitable for woody brambles, tree stumps and Ivy.
  • Coverage up to 66sqm per sachet

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