In September 2014 The Daily Mail ran a story about a 91 year-old woman whose house lost half its value due to an infestation of Japanese knotweed in her back garden. The article told how Elizabeth Abraham found out her Swansea house, which was forecast to be worth £80,000, would now sell for no more than £45,000 due to the aggressive wild plant. And even though many landlords seek rental yield rather than capital gain from a buy-to-let, the repercussions of Japanese knotweed taking root in a rental property are clearly alarming.
What damage can Japanese knotweed do to a property?
Knotweed can break through pathways, conservatory floors and even asphalt given the right conditions. And because banks and building societies need guarantees that the infestation will not return before granting a mortgage, proof of removal is also required – which can be very expensive.
Work must be carried out by specialist contractors who take steps to make sure that no pieces of knotweed accidentally escape while being transported off the site.
Firstly, topsoil is cleared to a depth of three metres extending to an area of 10 metres around the infestation and waste must be taken to an approved site for incineration. In certain cases a copper membrane is also laid down over the remaining soil.
The cost of this work and the inherent difficulty involved in raising a mortgage on a knotweed-afflicted property combined can lower its value considerably.
What is the law regarding Japanese knotweed?
Because it is potentially harmful to native species it is an offence under the Wildlife and Countryside Act 1981 to plant or cause Japanese knotweed to grow in the wild. It is also regarded as controlled waste site under the Environmental Protection Act 1990and has to be disposed of at licensed sites or by burning on site.
Site developers are not only bound by the same laws and could face potential prosecution or compensation claims for failing to deal with the problem, but could save substantial amounts of money by identifying Japanese knotweed early enough to evaluate the cost of wiping it out and disposing of it or negotiate a different price for purchasing land infected with it.
The Environment Agency has published the Knotweed Code of Practice to advise all those involved in the development industry about knotweed.
How did Japanese knotweed spread in the UK?
Knotweed has been referred to as the most economically important invasive non-native species in the UK. It was introduced as an ornamental plant in Victorian times and was also used by railway companies to stabilise embankments due to its fast-spreading nature.
It does not seed in the UK but spreads through the ground or when parts of the plant are moved by animals or people and is now in most urban areas of the UK.
How can I identify Japanese knotweed?
If you are worried that your property might be under threat you can find information on the Department for Environment, Food and Rural Affairs’ website which will help you identify it and point to other agencies which can provide advice.
How can I assess the extent of a Japanese knotweed infestation?
A Japanese knotweed survey will check for its presence and then determine the best treatment method and likely cost.
You can have a specialist inspection survey completed by qualified and accredited surveyors and engineers Property Assure. The firm promises straightforward, honest advice provided by independent and impartial qualified and accredited experts.
For more information please phone 0844 257 9696.
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