As a general rule of thumb, a knotweed infestation will affect the value of your home if it is within 7 metres of your property. If there is a large infestation further away than this but is still close to your boundary it can still cause an issue when selling your home, and always carries the potential that if untreated it will spread far and wide. Not all surveyors approach this issue with the same severity, and you may find that some completely ignore the presence of knotweed on a neighbouring property altogether. Look at our Japanese Knotweed National Register to see how close it might be to your home. The register is updated voluntarily by members of the public, gardeners and those working around homes and surveyors both independent and from the Japanese Knotweed Agency.