Homeowners face growing battle with Japanese Knotweed

The fast-growing and invasive plant Japanese Knotweed is a bigger headache for homeowners than ever, thanks to this year’s weather.

The wet and frosty spring, which was followed by dry weather and sunshine, has provided it with the perfect growing conditions, and some experts are predicting a surge in incidence of Japanese Knotweed, which is already thriving and rapidly growing.

Japanese Knotweed is estimated to affect up to 1.45 million homes across the UK, which equates to approximately 5% of residential properties. It can devalue a house by between five and 15 percent, and in some extreme cases, it has even almost completely devalued properties.

Sellers and buyers must realise there is a distinct possibility they will face either a current infestation of the plant, or evidence of it at a property in the past, and that this could halt or totally derail a property sale.

Home sellers have a legal obligation to declare Japanese Knotweed to buyers. The TA6 Property Information Form used to inform buyers of any negative issues affecting the home, includes a specific question pertaining to Japanese Knotweed.

Getting a mortgage on a property with or which has had Japanese Knotweed is not straight forward, and in some cases impossible. Most home insurance policies will exclude Japanese Knotweed, and won’t cover owners for damage to their or neighbouring properties, nor the cost of damage to remove or eradicate the plant.

Classified as a ‘controlled waste’ under the Environmental Protection Act 1990, Japanese Knotweed grows up to 20cm a day. If left unchecked, its deep, wide-ranging roots can tunnel through and destroy a homes’ foundations, drainage systems, and walls, putting properties at risk of damage as it can grow through cracks in concrete, brickwork, patios, asphalt, cavity walls, gutters, and drains, eventually forcing walls to break apart.

Removal and disposal of it has to be handled by a qualified expert, which depending on the size of the infestation, will cost anywhere between £3,000 and £10,000.

The only option for homeowners to cover any remediation or damage caused by Japanese Knotweed is for them to take-out an insurance policy that is specific to Japanese Knotweed. Policies that cover damage and the cost of treating, removing and eradication start at a set price of £40.00 and provide cover for five years with a cover amount of £20,000.”

Last week (22 June 2021), RICS issued new advice for the assessment of Japanese Knotweed in UK properties, to help affected homeowners and lenders with guidance so that sales can proceed.

Japanese Knotweed insurance policies are available via Index West Midlands, which provides conveyancing searches, reports and property transaction solutions such as environmental risk factors, HS2, utility and telecommunications reports, for commercial and residential property lawyers, real estate and agriculture lawyers.


Kate Bould is managing director of Index West Midlands Property Information. The firm operates across Warwickshire, Worcestershire, Herefordshire, Shropshire, Staffordshire, and the Black Country. For more information: https://indexpi.co.uk/offices/westmidlands.html. 

Today's Conveyancer