Environet UK has launched a free online tool for home sellers and buyers to check how much of the property’s value may be diminished by Japanese knotweed.
It allows a quick assessment to be made on the likely impact on value, which on average is around 10%, taking into account the size of the infestation and its distance to the nearest boundary.
The algorithm, developed with support from Expert Surveyors, a provider of RICS property valuation reports in the UK, was named JK-VIM.
Nic Seal, founder and managing director of Environet, said: “Lending practices for properties with Japanese knotweed are in urgent need of review, considering all that’s usually required is a professional treatment plan to deal with the problem and a sensible readjustment of the price.
“In reality, properties with knotweed are worth on average around 10% less than an unaffected property, which reflects the cost of treatment and the so-called ‘knotweed stigma’.
“Now, for the first time, sellers will be able to see for themselves whether it’s worth their while financially to have an infestation professionally treated before marketing a property, by seeing exactly how much its value is diminished.
“Buyers, meanwhile, can get a realistic idea of how much they should be offering.”
The tool also offers revised valuations if the infestation is treated by herbicide or excavation and has a 10-year insurance backed guarantee for the works.