Mortgage lenders including the building societies and high street banks refuse to lend money in the form of a mortgage where a surveyor identifies the presence of Japanese Knotweed on the property, at the property boundary, or where there is a highlighted risk of Japanese Knotweed coming to your property from another.
Mortgage refusal has also presented itself where no Japanese Knotweed was present on the site but is on adjoining land and can spread. Surveyors employed by the banks are instructed to look out for Japanese Knotweed.
Banks refuse mortgages because the plant can cause significant property damage and will devalue the property due to the risk level this poses. This affects the loan to value ratio and reduces the value of the security held by the bank. Lending money on a property with untreated Japanese Knotweed is just a risk the banks are not willing to take.