What damage can Japanese Knotweed do to a house?

Japanese knotweed is one of the UK’s most aggressive invasive plants and a serious concern for homeowners. While it rarely damages structurally sound properties, it can still cause significant problems if left untreated.

Knotweed spreads rapidly through underground rhizomes and can exploit weaknesses in a building’s structure. It’s capable of pushing through cracks in concrete, brickwork, paving slabs, tarmac, and even drains. Over time, this growth can destabilise patios, garden walls, paths, and outbuildings. If foundations or underground pipes already have minor faults, knotweed may worsen them.

Beyond physical damage, knotweed can drastically reduce a home’s value and make it harder to sell. Many mortgage lenders may reject applications or require a formal treatment plan before approving finance.

Professional intervention is essential. A PCA-registered contractor can carry out a multi-year herbicide programme, typically with a 5–10 year insurance-backed guarantee.

Ignoring Japanese knotweed could result in costly repairs, mortgage issues, and legal complications. Early detection and treatment are vital for protecting your property and financial peace of mind.