How serious a problem is Japanese Knotweed?

Japanese Knotweed

Japanese Knotweed can be a homeowner’s worst nightmare. Not only is this invasive weed virtually indestructible, but most mortgage lenders will be extremely reluctant to finance a property that has knotweed within seven metres of its walls.

So how concerned should you be if you’re looking at a property and your RICS Level 2 HomeBuyer Survey has identified Japanese Knotweed growing in the back garden?

What exactly is Japanese Knotweed?

If you haven’t heard of it before, it’s important to know that Japanese Knotweed is an invasive plant species that manages to thrive just about everywhere in the UK. Its aggressive growth (up to 10cm a day!) affects the growth of other plants, ultimately causing problems with biodiversity, flood management and even property damage.

In fact, the species is so pervasive that it is actually an offence to “plant or otherwise cause [Japanese Knotweed] to grow in the wild” under section 14(2) of the Wildlife and Countryside Act 1981. When trying to get rid of the plant, contaminated soil and plant rhizomes (roots) are classed as “controlled waste”, under part 2 of the Environmental Protection Act 1990.

It can be hard to identify Japanese Knotweed; in fact, several unrelated plants are often mistaken for it. Key characteristics to look out for are light green, shield-shaped leaves, tall, hollow stems that resemble bamboo and can grow up to 3 metres tall, and clusters of tiny white flowers that bloom in upright formations.

Which homes can be affected?

Thanks to its ability to grow in just about any condition, Japanese Knotweed can be found anywhere in the UK. The peak of its popularity was during the Victorian period, so properties built around this time are the most likely to suffer from a historic problem with the plant. This plant tracker is a useful tool for identifying how prolific Japanese Knotweed is in your local area.

Is it really that bad?

The speed and resilience with which this plant grows is known to cause damage to structures, particularly where weak points are already present. Tarmac, paving, building foundations and retaining walls can all succumb to knotweed in very little time if the plant is left unchecked. That said, detailed surveys have concluded that Japanese Knotweed isn’t actually any more destructive than other plants that are left to grow rampantly.

Japanese Knotweed maintenance is a constant to prevent it taking over an entire garden, and is extremely difficult (and therefore expensive) to eradicate entirely, and therefore, undesirable. According to the UK government, the cost of controlling existing Japanese Knotweed had risen to £1.25 billion in 2014.

It is perfectly understandable that you may want to steer clear of properties that have been diagnosed with Japanese Knotweed in the garden. However, it does not have to be a deal-breaker if you have already fallen for the house. Your best bet is to speak to an experienced surveyor and arrange for a Building Survey or specialist report to help you understand the potential implications if you do decide to proceed with the purchase.

Published on: Last updated: 24th April 2025

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kieran newcombe
13 October 2026
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Me and my partner have been going through the process of purchasing our first house and was recommended to get a Level 3 survey completed. From start to finish, H&S have been great. Quick and friendly correspondence, and communication was very good! The survey write up was in great depth and easy to understand. We have been in touch with them a couple times after the survey was completed and they have been incredibly helpful! I wouldn’t hesitate to recommend them to anyone, especially if you’re a first time buyer and this is all new to you. Reasonably priced and very happy customers. Thanks you! 👍
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We used this company nine years ago when we bought our house,and Andrew was excellent ,very thorough and went out of his way to come back when we needed some extra advise,he did a full home buyers report for us. Today - nine years on Chris and Jack came round.they did an excellent job and gave good advice. I can’t praise these guys enough, Very thorough and professional.with all the latest technology! We wouldn’t hesitate to recommend h & s Chartered surveyors. Thankyou very much! I
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20 June 2026
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I would highly recommend this company. I am very impressed with the service provided particularly the excellent communication, customer service and willingness to provide guidance and answer questions at all stages. I am in the process of purchasing a house in Teignmouth. Firstly, h&s were recommended by the Estate Agents. I looked on the website and liked what I saw, clear and concise in explaining all the options. When I rang the office I was also very pleased after speaking with Saffron, she is very helpful, she clearly explained everything and arranged the next steps. Chris soon got in contact with me and really has been excellent from there onwards. Firstly, he explained that as the property was an older building and had been converted he would be able to best assess whether it should require a Level 2 or Level 3 Survey on inspection. Chris said he would keep me informed on the day, which he did, via WhatsApp at my request as I was at sea on a Transatlantic Cruise at the time! He deemed that it just needed the Level 2 which was great. I got the report in a timely manner both electronically, and a bound hard copy. It is clear and easy to understand. I spoke to Chris after I’d had time to digest it, and he spent over an hour on the phone with me going through it all, explaining the recommendations and answering lots of questions which I had mainly about next steps to take, which was so helpful. What amazing customer service! Chris also reassured me that I can contact him again via a call or email should I need to. I very rarely write reviews but this service was so exceptional that I just had to. I would not hesitate to use this company again. This has by far been the most seamless part of the process of purchasing my new property! Thank you so much Saffron and Chris 😊
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Luke Brisco
21 April 2026
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Great service provided by the team four our survey needs. The Surveyor was very knowledgable and helpful with providing advice, with the report produced and sent over to us the following working day. Great communication and customer service, would definitely recommend!
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31 March 2026
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Friendly and professional company. Detailed and accurate report. Highly recommended and will use again in the future.
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Chris visited carried out two valuation reports for us, offering help and advice that went above and beyond (and probably saved us some money). Would highly recommend.
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30 January 2026
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Ian at h&s Surveyors provided an excellent survey. He provided a comprehensive report with lots of details and answered our specific queries really quickly. I would highly recommend h&s to anyone who needs surveyor services.
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28 January 2026
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Excellent service, very good reports and was most helpful for follow up advice for conveyancing would and have recommended to others to use their services.
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I am really thankful and appreciate of the service that the H&S Team have given me every step of the way since the very first phone call back in July. Their service has been exceptional - from the customer care over the phone to the surveying process itself - the efficiency and professionalism truly is 5 star! I would highly recommend the team for any survey and valuation report needs!
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Louise White
9 December 2025
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This was our fourth house purchase and H&S Surveyors were far and away the best we have used. Our surveyor, Chris, was extremely professional and approachable with excellent attention to detail. He was happy to follow up the report with further clarification over the phone as needed, and even supported with additional enquiries on some matters. After our first property fell through we had a second survey by Chris on our subsequent purchase. He had advised that the first required a Level 3 survey due to its age and condition; for the second, he advised that only a Level 2 was necessary as it was a newer build. We were very happy to trust his judgement and expertise. Office staff were also extremely helpful and communicative. We would thoroughly recommend H&S.

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