Ben Lindley, Company Director at Japanese Knotweed Ltd.
Last reviewed on 4th November 2025.
Japanese knotweed is widely known to have a high environmental impact, outcompeting our native vegetation, threatening biodiversity and limiting amenity space but the real cost of knotweed is felt by the construction industry with its ability to put your project on immediate hold.
Specialists in knotweed eradication Japanese Knotweed Ltd says: “There is a reason we say ‘KNOTWEED IS NOT TO BE IGNORED!‘ Aside from the worry of eradication costs and the commercial burden it puts on businesses up and down the UK, knotweed also has a high environmental impact, and ignoring it has a distinct knock-on effect for the end consumer – purchasing new builds from developments that didn’t deal with knotweed up front.”
The real cost of ignoring knotweed
Knotweed can remain dormant underground for up to 20 years, re-sprouting whenever conditions are favourable. Even minor soil disturbance can trigger new outbreaks. Many legal cases have concluded with significant legal fees and fines for the developer who didn’t deal with it at planning stage – not to mention the cost to remove it by the new property owners.
As shown below, we get called out to many a development after handover to treat or remove knotweed emerging through newly laid driveways and patios. This is the real cost of ignoring knotweed.
Dealing with knotweed underground
Knotweed roots are capable of growing through even dense clay, and when this happens around infrastructure such as pipes and cables or trees the problem of removal becomes a bigger challenge. Often knotweed will have caused damage to the infrastructure, as it grows through pipes it weakens the structure causing cracks that eventually leads to breakage.
Rhizome growth around tree roots can cause restriction which weakens the tree’s stability. Projects that involve dealing with these challenges can require specialist equipment such as Air Spade or Vacuum Extraction to minimise risk of further damage and protect the environment during works.
The vacuum extraction method is used when we need to work around infrastructure or natural habitats. Using less equipment and vehicles on site also reduces our carbon footprint. Being able to work around trees and live utilities without risk of harm or strike makes it a safer and more sustainable option that is kinder to the environment.
Limiting impact and protecting your investment
So what can we do to limit the construction hazard and project risk that is Japanese knotweed? The best option is prevention. Ensure knotweed cannot take hold, or worse, take over! Getting a survey carried out will arm you with the right information – if you have knotweed you’ll be given options to treat or remove it, and if you haven’t it’ll be the news you wanted to hear.
The best time to have a survey carried out at pre-planning stage, and it can be done now – whilst it’s still visible and before it gets going in spring.
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