Japanese knotweed: how it can affect your property and your mortgage


Japanese knotweed: how it can affect your property and your mortgage

New rules have been introduced for people who don’t control the spread of the invasive plant Japanese knotweed, meaning they could be fined up to £2,500 or given an anti-social behaviour order (ASBO).

Japanese knotweed (also known as fallopia japonica) is an extremely destructive and invasive plant. While it isn’t illegal to have it on your property, it is against the law to plant it and then not control it properly. Other invasive plants that are not native to the UK, like giant hogweed, are also subject to the new rules.

Problems with plants

To look at, Japanese knotweed seems like a harmless plant, with its heart-shaped leaves and little cream flowers. But to your home, it can prove a nightmare; causing structural damage and making it impossible to sell.

The plant can take hold on pretty much any surface, including growing through your walls and floors and even through tarmac. It can grow up to 20cm a day, so it can quickly start to cause damage to your property in a matter of days. Not only could this create problems for your walls if the Japanese knotweed takes hold in them, but it can also cause issues to the foundations of your property as the plant’s roots can grow metres deep. There is also a possibility that it can cause damage to your pipes, as its roots can block waterways.

However, it isn’t just structural problems that Japanese knotweed can cause to your home. If you’re looking to sell your house, some estate agents may value it at much lower than others on the street, and mortgage providers may not lend to your buyers at all. Earlier this year, a woman had the value of her house cut from £80,000 to just £45,000 because of an infestation of Japanese knotweed on a piece of neighbouring land. If you discover the dreaded plant on your grounds, you could find it difficult to find a buyer at all.

Tackling the weeds

If you’re attempting to identify Japanese knotweed, look out for red tinged shoots starting to grow on your property around early spring. It has large heart-shaped leaves in a zigzag pattern along a hollow stem, and produces clusters of little cream flowers in late July. It will die back between September and November, leaving brown canes, and can grow as high as 3m in summer. If it turns out that you do have Japanese knotweed on your grounds, don’t panic – it isn’t immediately a death sentence for your property.

Though you don’t have to get a specialist to help, it can be tricky to attempt to remove Japanese knotweed on your own. This isn’t because it’s a danger to humans but it is notoriously resilient and difficult to get rid of. You might want to consider contacting a specialist company who will be able to destroy it more thoroughly and make sure it has less of a chance of being able to grow back.

If you do decide you want to tackle it yourself, you could try digging it out, depending on what stage of growth the knotweed is at. Be warned that its roots can go deep into the earth, so it might be difficult to get out. Also, once you’ve got the Japanese knotweed out, the soil is classified as controlled waste, so you’ll only be able to dispose of it at special landfill sites. This government document from the Department for Environment, Food & Rural Affairs (Defra) outlines the other ways that you can eradicate Japanese knotweed, though keep in mind that some pesticides should only be used by professionals.

When you’re considering buying a house it may be worth paying for a thorough survey, as problems such as Japanese knotweed may be identified. You may still decide that you want to buy the property, especially if the knotweed problem hasn’t got too serious yet, but you will be aware of the issue and you could stipulate that the seller has to treat it as a condition of the sale.

If you’re going to be applying for a mortgage shortly then make sure you check out our mortgage guide for top tips >

If you’re considering getting a loan to remove Japanese knotweed from your property then you may benefit from reading our loans guide >