The legal implications of Japanese Knotweed

Professional negligence solicitor Emma Slade looks at the law relating to Japanese Knotweed

Did you know that it cost the UK taxpayer over £70 million to remove 10 acres of Japanese Knotweed during the construction of the Olympic Park in London?

Or that it is an offence under the Wildlife & Countryside Act to plant or grow Japanese Knotweed in the wild?

It is also an offence under the Environmental Protection Act 1990 if it is not disposed of properly (you must not put it in your household waste or compost bin).

Then there is the eye-watering fact that Japanese Knotweed can grow at the rate of up to 20cm a day!

Fallopia Japonica: Japanese Knotweed and Surveyor’s Negligence

I discovered all these interesting facts about Fallopia Japonica in a case I recently dealt with. However, my client certainly didn’t find it “interesting”. He was understandably concerned as there are so many horror stories being told about this invasive weed which, aside from growing at an incredible rate, it has roots (or Rhizomes as Alan Titchmarsh may more correctly refer to them as) that can grow down to a depth of three metres. Given that modern day houses only need footings to a depth of one metre, stories of householders finding Japanese Knotweed growing up through their living room floor no longer sound so unbelievable. Or that in some instances, it is actually cheaper to knock the house down as the damage caused by its invasive nature means it is too expensive to treat.

The case I was dealing with involved a surveyor who had failed to notice that the red-stemmed, bamboo-looking bush at the end of the garden was in fact Japanese Knotweed. The client, on moving in to the property, was told by his next door neighbour that something had to be done about “that pesky plant”. Investigations showed that it was indeed Japanese Knotweed, brought on site by the property developer in contaminated soil. The property developers had gone in to liquidation by the time all this was identified so a legal claim could no longer be made against them. Instead, we had to bring a professional negligence claim against the surveyor.

Given that Japanese Knotweed was very much a feature in the press at the time and that the RICS had recently published a paper about it, it was concluded that a reasonably competent surveyor should have been alert to the possibility of the presence of the knotweed. The claim therefore succeeded and the surveyor learnt a very expensive horticultural lesson.

Japanese Knotweed and Estate Agents’ Duties

But it isn’t just surveyors or property developers who can be held legally liable for Japanese Knotweed as I was reminded of just the other day when i received an enquiry from a prospective client who had called our free professional negligence helpline.

The caller and her husband had exchanged contracts on the purchase of a house, but before completion the estate agent admitted that previous buyers had pulled out of the house purchase because of the presence of the dreaded Japanese Knotweed. There were delays therefore in completion as the vendors had to make arrangements for the Knotweed to be treated. Understandably the caller was concerned that the property may be devalued as a result of being ‘blighted’ by the fact that Japanese Knotweed had been present. In addition there was the stress and worry they had endured throughout the these trials and tribulations: Would their lenders pull out? Would they then be in breach of contract?

Given the amount of damage that Japanese Knotweed can cause to a property, lenders obviously balk at accepting an affected property as security for a mortgage. When the problem was first identified, mortgagees refused to even consider lending on a property that had Japanese Knotweed anywhere near it. At that stage, the Royal Institution of Chartered Surveyors issued a report and since then, a lot of lenders have relaxed their criteria. Many will now offer a mortgage if the knotweed is treated and a 10-year insurance backed guarantee is obtained. Fortunately, in this instance, after treatment paid for by the Vendor, the lenders were prepared to accept the property as security. As the house had already been bought at a price that was much lower than market value, there was no evidence of the property diminishing in value. The only thing remaining was the stress and worry the purchasers had had to endure. As the agents had readily admitted that they knew of the problem prior to exchange, there was a clear case of a breach of the Consumer Protection from Unfair Trading Regulations 2008 (CPRs) which specifically gives Japanese Knotweed as an example of information an agent should impart. Because the Courts are reluctant to compensate for ‘stress and inconvenience’, I recommended that the caller take the complaint further to The Property Ombudsman. This service, which is free of charge, can award damages of up to £25,000 for stress and inconvenience.

RICS Guidance on Japanese Knotweed

According to the latest RICS guidance, Japanese Knotweed is not such a great problem. Provided specialist advice is sought and care is undertaken not to damage it (rhizomes will grow from each cut), it can be reliably treated and rarely causes damage to property. Lenders are starting to accept this and provide mortgages on property provided appropriate safeguards are put in place. It is only the horror stories from the popular press that are still remembered and it is this which affects the value – and saleability – of a property blighted by Japanese Knotweed.

Free Legal Helpline

If you have encountered problems with Japanese Knotweed and wish to consider a negligence claim against a surveyor or other professional then call our free legal helpline on 0808 139 1595 or contact solicitor Emma Slade direct at [email protected]


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