Parliamentary Committee finds home lenders are over cautious about risk of Japanese knotweed

Mortgage lenders are overly cautious and relying on flawed science which is leading to the value of homes being reduced due to invasive plant Japanese knotweed, according to a Parliamentary Committee.

The House of Commons Science and Technology Committee said in a new report that other invasive plants do not have the same effect and points out that lenders in Europe do not adopt the same stance.

Environet, a Japanese knotweed specialist removal firm, estimates that approximately 850,000 to 900,000 UK households are affected and suffering an average reduction in value of around 10%, knocking almost £20 billion off property values.

It points out that this ‘overly cautious’ approach to the plant is leaving home owners unable to sell, even in cases where the invasive plant poses no practical threat.

It sets out how a seven meter rule proposed by the Royal Institution of Chartered Surveyors (RICS) in 2012 is taken as the cut-off point but is no longer backed up by research. The Committee has now called for the Department for Environment, Food and Rural Affairs to commission a study of international approaches to Japanese knotweed in terms of property sales.

‘It is clear that the UK’s current approach to Japanese knotweed is more cautious than it needs to be, especially when comparing it to that of other countries,’ said Norman Lamb, chair of the Science and Technology Committee.

‘We need an evidence-based and nuanced approach to the issue, one that reassures owners and buyers that they will not be subject to disproportionate caution when trying to sell or buy a property,’ he added.

The report comes at a time when a separate piece of research shows that 32% of people in Britain would buy a property with Japanese knotweed, but at a reduced price. Most would want a discount of 6% to 10%, according to the You Gov research commissioned by Japanese removal specialists Environet. A further 15% would seek to reduce the price by more than a quarter.

The poll found that awareness grows of the UK’s most invasive plant is growing with 78% of British adults now aware of it compared to 76% in 2018 and 75% in 2017. But it says that with the treatments and guarantees now available to deal with it, home buyers have greater peace of mind that it’s a problem that can be solved.

While half of those who are aware of the plant would walk away from a property which had Japanese knotweed, this is significantly less than the 78% who stated they would not buy an affected property two years ago, suggesting people are becoming increasingly pragmatic.

Indeed, according to the firm Japanese knotweed can now be completely removed within a matter of days, at any time of the year, using a digging out method that sifts the earth to remove all viable rhizome roots from the infected soil. Once the problem has been tackled in this way or using a longer term herbicide treatment and an insurance backed guarantee has been secured, almost all mortgage lenders will lend against the property and sales can proceed unhindered.

‘With an estimated 5% of all UK properties now affected by Japanese knotweed, either directly or indirectly, it’s encouraging to see home buyers becoming increasingly rational in their approach. If left untreated, Japanese knotweed can cause considerable damage to a property which is why buyers and lenders are right to insist that there is a professional treatment plan in place before they agree to proceed,’ said Nic Seal, managing director of Environet.

‘Due to the stigma around Japanese knotweed the property value will almost certainly be impacted, but all that’s required is a sensible renegotiation of the price. People are realising it doesn’t have to be a deal breaker,’ he added.

According to chartered surveyor Paul Raine, director of Expert Surveyors Ltd, the key to selling a property affected by knotweed is a Japanese Knotweed Management Plan from a reputable specialist. ‘Always be honest if the property you’re selling is or has been affected, or it could come back to bite you in the form of litigation from your buyer further down the line,’ he said.

Japanese knotweed was first introduced into the UK from Japan in the 1850s as an ornamental plant, but it is now number one on the Environment Agency’s list of the UK’s most invasive plant species. Growing up to three metres in height, it spreads rapidly between May and September and can push up through asphalt, cracks in concrete, driveways, cavity walls and drains.