How serious is Japanese Knotweed and how does it affect your property?
Japanese Knotweed is an extremely serious problem because it can affect the very foundations of your property.
It can cost thousands of pounds to remove depending on the size of the problem and can also affect the re-saleability of a house if it is not dealt with properly.
In fact, it can devalue a house between 5-15%, and in some very extreme cases, it can completely devalue the property. The amount that a house is devalued depends on the severity of the problem and its proximity to other buildings.
What is Japanese Knotweed?
Japanese Knotweed is an invasive strong clump-forming perennial weed that reaches up to 10 feet high with deeply penetrating roots (rhizomes) that can grow 20 feet below the ground.
It was introduced in the UK from East Asia as an ornamental garden plant by the Victorians in the middle of the eighteenth century.
Why is Japanese Knotweed so dangerous to your property?
Although Japanese Knotweed is not dangerous to humans or animals, its ability to relentlessly grow up to 10cm a day can cause tremendous damage to your property.
For instance, it can cause the following problems:
- Significant structural damage to weak points in masonry and property foundations.
- Damage and blockages to underground drains.
- Ruined driveways, patios, and other paved areas.
- Damage resulting in the collapse of boundary walls.
All this can affect the sale of your property and cost thousands of pounds when rectifying the damage it has caused.
It is best to get it removed by an approved specialist company that is likely to excavate and use herbicides over a few years to be totally effective.
The plant together with the excavated soil must be disposed of as “controlled waste” in accordance with strict regulations.
Can you sell a property with Japanese Knotweed?
Yes, properties with Japanese Knotweed can be sold and do sell, but lenders are extremely cautious about providing mortgages for properties with Japanese Knotweed because of the risk of damage posed by the plant and the potential problems it can cause if not treated properly.
It is actually a criminal offence under The Wildlife and Countryside Act 1981 to knowingly allow Japanese Knotweed to spread from your property to your neighbours' properties.
Since 2013, someone selling a property is required to state whether Japanese Knotweed is present on their property information form or “TA6 form” which is used for conveyancing by their solicitor.
If the property is affected by Japanese Knotweed and you want to buy the property, your solicitor and mortgage lender would normally require evidence that a Japanese Knotweed Management Plan for its eradication from an approved company was in place along with a transferable guarantee covering several years.