The invasive weed, which is difficult to destroy and has the potential to cause thousands of pounds worth of damage to a property, can impact a mortgage decision because lenders consider it a risk.
Indeed, most would only agree to lend if they knew a treatment plan was in place by an approved specialist.
Japanese knotweed removal firm, Environet, estimates the plant now affects between 4% and 5% of UK homes and can prove costly for homeowners.
Indeed, it said approximately 850,000 UK households suffer an average reduction in the value by around 10% as a result of knotweed.
Now Environet has created an online tool which will make a quick assessment on the likely impact on value. This will enable sellers to determine whether it is financially worthwhile to have the weed professional treated before selling the property.
For buyers, meanwhile, it means they will be in a stronger position to negotiate a lower price which is fair and accurate.
Nic Seal, founder and MD of Environet said: “Lending practices for properties with Japanese knotweed are in urgent need of review, considering all that’s usually required is a professional treatment plan to deal with the problem and a sensible readjustment of the price.
“In reality, properties with knotweed are worth on average around 10% less than an unaffected property, which reflects the cost of treatment and the so-called ‘knotweed stigma’.”
The new tool called JK-VIM means sellers will be able to see how much the Japenese knotweed diminishes the value of their property by, and will enable them to decide whether to pay to get it treated before they move.
The buyers, meanwhile, will also be able to gain a realistic idea of how much they should be offering.
