SPRING is on its way, which means one thing for surveyors – the first glimpse of the potentially invasive Japanese knotweed plant.

Now present across the whole of the UK, this tough, fast growing weed can grow up to 10cm a day and its invasive root system can stretch for 7m.

Brick walls, foundations, paving slabs and tarmac are no barrier and the knotweed can cause structural damage if it gets out of control, potentially causing a property to lose value.

Japanese knotweed can reach heights of 3m and the first sign of its presence are purple shoots appearing in early spring, leading to the plant being fully grown by late summer.

Dan Lowery, director of surveyors at Romans Surveyors & Valuers, said: “If Japanese knotweed is suspected the advice is to get a specialist in to confirm the extent and course of remediation as this can be costly and take a number of years. The presence of knotweed could also affect the mortgage ability of a property.”

The knotweed has now been classified as a notifiable plant by the Department for the Environment, Food and Rural Affairs (DEFRA).

Surveyors who spot the plant in a property’s garden, or in the grounds of adjoining properties, are obliged to make note of it, resulting in some mortgages being refused.

But the presence of Japanese knotweed does not necessarily mean your property will lose value or become unmortgageable.

The Royal Institution of Chartered Surveyors (RICS) issued an information paper, providing risk guidance to mortgage valuers and has concluded that despite the challenges it presents, the plant can be successfully tackled with expert advice and appropriate treatment.

“While this invasive plant can be difficult to control, timely treatment can minimise its impact,” said Dan.

“As the treatment industry develops and matures, we join RICS in hoping that Japanese knotweed will soon become just one more consideration in the complex valuation process.”

Romans Surveyors has put together a guide on ‘Everything you need to know about Japanese knotweed’ which can be found at romans.co.uk/insights-list. If you have found Japanese knotweed in your property and you’re not sure how to effectively treat it always talk to a professional surveyor, who will be able to measure the magnitude of the problem and estimate the cost of treatment.