The problem is so acute that a specific question is asked in the Law Society’s standard property information form. Question 7.8 tells owners that Japanese knotweed is an invasive plant that can cause damage to property and that it can take several years to eradicate; it then asks ‘is the property affected by Japanese knotweed?’ Of course, not everyone will know whether or not they have a knotweed problem but the consequences of how a vendor answers the question can be enormous.
There do not seem to be any reported decisions dealing with private sales but a number of cases are now progressing through the Courts and it’s plain that, giving the wrong answer to question 7.8, can amount to an actionable misrepresentation. Most obviously, if the vendor ticks the ‘no’ box when they know that their property is affected by knotweed, then there is a clear misrepresentation to the purchaser. However, even ticking the ‘Not Known’ box will be a risk if the vendor has any cause to think that knotweed might be present on their property. But what of the consequences? Some surveyors suggest that a purchaser’s damages will be significant, based on the cost of removal and management coupled with the property having a much reduced value. It can take years to eradicate knotweed and, understandably, purchasers are reluctant to take on the risk.
Of course, problems do not begin and end in an owners’ own backyard. Knotweed can cause a nuisance to neighbours and a whole neighbourhood can become blighted once the plant spreads. This was only too clearly demonstrated in the County Court case of Williams & Waistell v Network Rail Infrastructure limited (unreported). Here knotweed had spread from the Defendant’s land into the gardens of adjacent bungalows. Two owners brought a claim for damages based on private nuisance and, at first instance, succeeded on the basis that there had been an unlawful interference with their enjoyment of their property. The alternative claim based on encroachment failed only because there was no actual physical damage. Most worrying for property owners, the damages awarded were significant covering the cost of treatment and an insurance backed guarantee together with the diminution in value of the claimants’ properties.
That decision is subject to appeal but it demonstrates the risks of having knotweed and not controlling it. The amount of damage recovered shows the potential losses a property owner or vendor might face if they don’t control knotweed or if they misled a purchaser.