Landowners will be able to claim damages if the “pernicious” Japanese knotweed has encroached on their property, after a court of appeal ruling.

In a decision that could have implications for landowners across England and Wales, three judges ruled in favour of two householders whose properties had been affected by the hazardous plant.

Japanese knotweed, which grows quickly and strongly and spreads through its underground roots or rhizomes, can undermine the structural integrity of buildings and is expensive to treat.

Stephen Williams and Robin Waistell, who own two adjoining bungalows in Maesteg, south Wales, made a claim against Network Rail, which owns the land immediately behind their properties. The plant has been present on Network Rail’s land there for at least 50 years, and the pair first complained about encroachment in 2013.

They brought a successful claim against Network Rail at Cardiff county court and were awarded damages in February last year. Network Rail challenged that decision, but the court of appeal ruled that the homeowners were entitled to damages because the plant’s rhizomes had extended beneath both of their properties.