According to Environet UK, which describes itself as invasive plant specialists, this compares to sellers of second hand homes who have to compile an information document, TA6 form, as part of the conveyancing process which directly asks if a property is affected by knotweed.
The firm added that sellers who provide false information could be subject to a “misrepresentation claim” from the buyer, which would recover the cost of plant removal and any fall in value of the home as a result.
Environet said the TA6 form is not a legal requirement for new build sales, so they are not usually filled out by residential developers.
The firm said questions relating to building alterations were not relevant to new-build residential developer while questions regarding warranties and guaranties were often provided separately and covered by the National House Building Council (NHBC) new-build guarantee.
Environet urged buyers and solicitors to ask whether the land had been treated for knotweed before or during construction works, especially as many construction projects are on brownfield sites where the plant could be widespread.
It added that buyers could be unaware that their property has knotweed if it was not included in solicitor enquiries and would be unable to verify if a professional treatment plan had been implemented or guarantees secured.
The company said if the buyer later found a new home was impacted by knotweed, their only option was to pursue the developer for breach of contract, which would be more difficult to prove than misrepresentation.
Environet said if a developer could not provide assurances that the land is free from knotweed, then buyers could commission a knotweed detection dog survey.
Nic Seal, managing director and founder of Environet, said: “Buyers of new build homes are not currently given the same protection from the risks associated with Japanese knotweed as buyers of second hand homes. A large proportion then increase this risk further by failing to commission a survey on their new home, as they think, quite incorrectly, that the NHBC warranty is sufficient to cover them for any defects.
“Put simply, the Japanese knotweed question must be asked. If the residential developer denies that knotweed was present but it is subsequently discovered, this evidence will give the buyer a strong case to sue the developer for misrepresentation, the cost of treatment and any proven diminution of the property’s value.”
Paolo Martini, director at Cobleys Solicitors and a leading legal expert in the field of Japanese knotweed law, said: “The excitement of new-build purchases, often agreed off plan, quickly turns to dismay within 12 months when knotweed emerges. Large developments, particularly those on brownfield land which is more likely to be contaminated, can lead to problems for developers and new home buyers alike where knotweed is ignored or remediation fails.
“Japanese knotweed must be treated by an expert, with full disclosure given to the buyer and quality guarantees provided within the contract of purchase.”
