Can you get a mortgage on a house with Japanese knotweed?

Full answer

Japanese knotweed is an invasive plant that spreads aggressively and can affect a property's saleability rather than usually causing structural damage. Its main impact is on mortgage lending and value, because lenders worry about the cost of eradication and the effect on resale. How it works in practice: when a surveyor inspects, they assess how close the knotweed is to the dwelling. Historically a 7-metre zone around the building was the rule of thumb, though guidance has shifted towards assessing actual risk to the structure and neighbouring land. If knotweed is present, lenders typically want a treatment plan from a specialist contractor backed by an insurance-backed guarantee (IBG), commonly running for 5 to 10 years, before they will advance funds. With that paperwork in place, many mainstream lenders will proceed on normal terms. Who it affects: buyers and sellers of affected properties, and neighbours - allowing knotweed to spread onto adjoining land can lead to civil claims. Sellers must disclose known knotweed on the TA6 property information form; failing to do so can expose you to a misrepresentation claim after completion. The financial impact varies. A property with active, untreated knotweed close to the house may attract fewer lenders, a lower valuation, or a price reduction to reflect treatment costs and stigma. A property with a completed treatment programme and a transferable IBG is usually far easier to finance. Treatment is normally either herbicide programmes over several seasons or physical excavation and removal, which is faster but more expensive. There is no specific tax figure here; the effect is on mortgageability and price. If you are budgeting for a purchase, model your borrowing with a mortgage calculator and factor any agreed price reduction. Always commission a specialist survey rather than relying on a standard valuation if knotweed is suspected.

Try the calculator