Half of the buyers and renters questioned in new research said they would walk away from a property if Japanese knotweed were found. For conveyancers, that statistic should change the way the issue is reported. A buyer does not merely need to know that knotweed exists. They need to understand what it could mean for the mortgage, the price and their ability to sell later.
The finding comes from research commissioned by Confused.com and reported by The Intermediary. The underlying Confused.com research involved 2,000 UK homeowners and renters.
The detail is as striking as the headline. Although 92 per cent had heard of Japanese knotweed, 76 per cent could not confidently identify it. Forty four per cent of those affected said they had been unaware of its presence before their sale or rental agreement. The same proportion said it had delayed a sale or mortgage, while 37 per cent reported a reduction in the property price.
These findings expose a difficult contrast. Knotweed is widely feared but poorly understood. That combination can turn a manageable issue into a transaction problem, particularly if it is identified late.
The headline needs one important qualification
The survey finding relates to buyers and renters together, rather than buyers alone. It records what respondents said they would do, not the result of observing completed property transactions.
It should therefore not be treated as evidence that every property affected by Japanese knotweed will lose half of its potential buyers. Nor does the presence of the plant automatically make a property unmortgageable.
What the finding does establish is the strength of consumer concern. Even where treatment is possible and lending may remain available, the stigma can affect demand, negotiation and confidence. That is a practical risk which a buyer may reasonably regard as material.
Japanese knotweed is not a simple yes or no issue
The old approach often reduced knotweed to two questions. Is it present and is it within a particular distance of the property?
The current RICS professional standard on Japanese knotweed and residential property takes a more considered approach. Surveyors assess the effect of the plant on the use and enjoyment of the property, the risk of damage and the need for management. The circumstances of the individual property matter.
This means that the useful question is not simply whether knotweed can be seen. A buyer may need to know:
- where the knotweed is growing;
- whether it is on the property or adjoining land;
- whether it affects amenity or causes damage;
- whether a specialist has inspected it;
- whether treatment is required;
- whether a management plan already exists;
- whether any guarantee can pass to a buyer; and
- what the proposed mortgage lender requires.
Those questions cannot always be answered by the conveyancer alone. The legal work must connect with the survey, the seller’s replies, specialist evidence and the lender’s instructions.
A buyer’s inability to identify knotweed matters
The finding that 76 per cent of respondents could not confidently identify Japanese knotweed is particularly important. A conveyancer should not assume that a buyer will recognise the plant during a viewing or understand a cautious reference in a survey.
Equally, the conveyancer is not expected to identify vegetation from photographs or offer an expert opinion outside their competence. The correct response to uncertainty is usually to make sure it reaches the appropriate expert.
If the property information form, search result, valuation, survey or correspondence raises a concern, it may be appropriate to ask the surveyor to address it expressly or recommend a specialist assessment. The client should understand why the question is being raised and why it should be resolved before exchange.
The seller’s answer is evidence, not a guarantee
The property information form can be an important part of the investigation. Its wording and the seller’s response must be considered using the version applicable to the transaction.
A negative answer does not necessarily prove that knotweed is absent. It records the seller’s response to the question asked. If other material conflicts with that answer, further enquiry may be needed.
The research reports that 9 per cent of affected owners did not disclose knotweed when selling or renting. That finding should not be used to presume that an individual seller has been dishonest. It does, however, reinforce why the transaction should not depend on one answer in isolation where other evidence raises doubt.
Conveyancers also need to avoid treating silence as reassurance. An unclear or qualified answer may require investigation just as much as an express disclosure.
The mortgage question can change with the lender and the date
A property affected by knotweed may be acceptable to one lender subject to evidence, but unacceptable to another on the information available. Requirements can address specialist reports, management plans, guarantees, valuation and reporting obligations.
Our earlier article, Are Lenders Putting Conveyancers in a Stranglehold over Knotweed Obligations?, appeared in the supplied export of unindexed About Conveyancing pages. It records how lender instructions could place detailed responsibilities on the conveyancer and why a simple reference to knotweed might trigger a more demanding reporting exercise.
The related article, Japanese Knotweed: Knot Disclosing to Lenders, shows that differences between lender requirements were already creating practical difficulty in 2016.
The historic wording in those articles should not be used as a statement of current lender policy. Its value is different. It demonstrates that requirements have changed and have not necessarily been uniform. The conveyancer must check the instructions applying to the lender and transaction in hand.
A mortgage completed before, so why is there a problem now?
This is a common and understandable question from an owner whose sale or remortgage has stalled.
The earlier lender may have applied different requirements. The knotweed may have developed or spread since the purchase. A later surveyor may have identified something not recorded previously. The present buyer may have a different lender, or the same lender may have revised its policy.
The existence of the earlier mortgage does not prove that the property was readily acceptable across the wider market. Nor does a new objection prove that the original advice was inadequate.
A sound investigation needs to establish what was known at the time of purchase, what the seller disclosed, what the survey or valuation recorded, what the lender then required and what the buyer was told.
A treatment plan does not make the issue disappear
Professional management can make a material difference. The survey found that 84 per cent of respondents would want a treatment plan before proceeding. That suggests evidence of control can restore some confidence, even where the plant itself remains a concern.
However, the words “treatment plan in place” should not end the investigation. The documents may need to establish:
- who prepared the plan and whether they have suitable credentials;
- the land and growth covered by it;
- the treatment already completed and the work remaining;
- who is responsible for future visits and payments;
- whether there is an insurance backed guarantee;
- whether the benefit can be transferred to the buyer; and
- whether the evidence satisfies the valuer and lender.
A plan relating only to the seller’s garden may not resolve growth on neighbouring land. Conversely, knotweed on adjoining land should not automatically be treated as though it were established beneath the house. The location and expert assessment matter.
The report on title should explain the decision
A report that merely states that Japanese knotweed has been disclosed leaves the most important work to the buyer.
The client should be told what evidence has been obtained, what remains uncertain, what the lender requires and what the issue may mean for use, value and a future transaction. If specialist advice is recommended, the buyer should have the opportunity to obtain it before exchange.
The report should also distinguish between present facts and future possibilities. It may be possible to confirm that a management plan exists. It may not be possible to guarantee that the plant will never recur, that every future lender will accept the property or that there will be no effect on resale.
That is not a reason to give vague advice. It is a reason to explain the uncertainty clearly enough for the buyer to decide whether to proceed, renegotiate or withdraw.
What if the knotweed is discovered years later?
An owner may discover knotweed only when a new buyer’s survey is carried out or a remortgage valuation raises it. The first priority is usually proper identification and an assessment of the current problem.
The next question may be whether the issue existed, or could reasonably have been identified, when the owner bought. The conveyancing file, the seller’s property information form, the survey, the valuation, photographs, treatment records and lender requirements from the time may all be relevant.
The Would I Buy page on Japanese knotweed discovered after purchase explains how the current sale or remortgage problem can be considered alongside the historical purchase records. It does not assume that anyone was at fault. It asks the more useful first question: if the buyer had known and understood the issue, might it have changed what they did?
The lesson behind the 50 per cent figure
Japanese knotweed is neither an automatic reason to abandon a purchase nor an issue to dismiss with a standard paragraph.
The research shows a substantial risk that buyers will react strongly when it is discovered. That reaction may be influenced by fear, but it still has consequences for value, mortgageability and marketability.
The best response is early investigation, reliable expert evidence, lender specific checking and advice that explains the practical choices before exchange.
A buyer who understands the position may proceed with a treatment plan and suitable evidence. They may negotiate the price. They may decide the risk is not for them. Each can be a rational outcome.
The conveyancing failure is not that a properly informed buyer chooses to walk away. It is that the buyer reaches exchange without appreciating why so many others might.