Problems found after you bought · Japanese knotweed
When I bought this property, I didn’t know Japanese knotweed could hold up a sale or a remortgage. Now I’m stuck.
Would you have bought the property if you had known?
If you had known about the knotweed before you committed — and understood the problems it could cause when you later came to sell or remortgage — would it have changed your decision?
- Would you have paid the same price?
- Would you have wanted it investigated first?
- Would you have walked away?
If knowing about the problem might have changed what you did, the next question is obvious.
Did you receive the right advice when you bought?
You may not know the answer yet. But if nobody explained the problem, or you are now questioning what you were told at the time, that is worth looking at.
You don’t need to know whether anyone was at fault. Tell us what happened and when you bought. We’ll talk it through with you.
Why knotweed stops a sale or a remortgage
Knotweed can cause real damage. But in many transactions the immediate practical problem becomes something narrower than people fear: mortgageability, valuation and saleability. Knotweed can prompt a lender or a valuer to require further evidence about the nature of the infestation and how it is being managed.
A surveyor assessing knotweed under the current RICS professional standard assigns it to one of four management categories, and what happens next depends on that assessment and on the individual lender’s policy. Some categories point towards specialist advice and a management or treatment plan, often with an insurance-backed guarantee that passes to a new owner; others do not call for remediation as a condition of lending. Requirements differ between lenders, so two buyers with two different lenders can get two different answers on the same house in the same week.
How it usually comes to light
A buyer’s survey
The most common route. A surveyor notes knotweed on or near the boundary and the buyer’s lender asks for more.
A remortgage valuation
You are not selling and nothing has changed — but a fresh valuer sees what an earlier one did not, or did not record.
A neighbour or the council
Growth from adjoining land, or a notice, brings it into the open before any transaction begins.
The property form
Filling in the seller’s information form makes you look properly for the first time, and you find it.
What you can do about it now
Start with identification and a specialist assessment from a contractor belonging to a recognised trade body. The assessment drives everything else, including whether treatment is needed at all. If a management or treatment plan is appropriate, expect it to run over several years rather than a single visit, and expect a buyer’s lender to want to see the guarantee rather than the intention. Tell your buyer early — a plan in place is a much easier conversation than a plan being arranged. And if the growth is coming from adjoining land, establish that, because your position and your options are different.
If you already have a solicitor acting on the sale or the remortgage, start with them. They can ask the buyer’s solicitor exactly what the buyer’s lender requires, which is usually a faster route to an answer than guessing at it. Requirements differ between lenders, so the quickest route is to establish exactly what the lender involved in this transaction wants.
What happened when you bought?
Knotweed is long-lived. It may have been present when you bought, or it may have become established since. That is a question of fact rather than an assumption — and it is a question with a paper trail.
Several records from the time may matter, and most of them still exist somewhere. The seller completed a property information form; depending on when you bought and which version was in use, it may have contained a specific question about Japanese knotweed. A valuer or surveyor is likely to have looked at the property for your lender, and possibly for you. There is the conveyancing file itself. And your lender gave your conveyancer written instructions about what to do if certain issues came up.
Was this property really mortgageable when you bought?
Getting a mortgage when you bought does not necessarily tell you how readily mortgageable the property was across the wider market. There are two historical questions worth asking.
What did your own lender’s requirements say about Japanese knotweed when you bought? And how were other mortgage lenders treating Japanese knotweed at the same time?
Mortgage lenders did not necessarily take the same approach, and their requirements changed over time. That means both which lender you used and when you bought can matter.
Lenders set out in writing what they expect a conveyancer to do about particular features of a property. Those instructions are revised regularly, and superseded versions drop out of public view, which can make a question as simple as what was my conveyancer told about knotweed in the year I bought? surprisingly difficult to answer from the sources available today. Lexsure has retained historical lender-specific conveyancing requirements since April 2007, so where the records permit they can help reconstruct what your lender’s requirements said at the time and how that compared with the wider lending market.
Across that period, 14 lenders have had express requirements about Japanese knotweed on record, addressed across 2 separate places in their instructions. The earliest express appearance we can identify in the material we hold dates from 2014; the most recent recorded change of wording is 2026.
Two points of precision, because they matter. “Earliest identified” means the earliest express appearance in the material we hold — not the date any requirement began. And where our material for a particular lender and period is incomplete, that lender is left out of these figures rather than counted as having said nothing. A gap in the record is a gap, not evidence of silence.
So — when did you buy?
Changing the year here doesn’t send us an enquiry or tell us who you are.
An example of the kind of wording in force 2007 to 2014
One lender’s requirements, not named, by way of illustration. Requirements were not uniform and this is not the wording that applied to your purchase — that depends on your lender and your completion date.
No lender handbook Part-2 (specific) requirements were published prior to 2015. But professionals were still under a duty of care on this topic. It is still worth speaking to us even if the purchase predates 2015.
If we find no express requirement for your lender
Where our material for your lender and period is complete, the answer may simply be that no express knotweed wording appears in it. Where our material is incomplete, we treat that as a gap in what we hold — not as evidence that your lender said nothing.
Either way, the lender’s instructions are only one part of the record from the time.
It isn’t all about mortgage lenders
Historical lender requirements can help us understand how mortgageable the property was when you bought. But they are only part of the picture.
Lexsure also holds historical Report on Title material showing the kinds of Japanese knotweed issues that have been addressed when conveyancers report to homebuyers. Among the themes that material covers:
What the seller said
What had the seller disclosed about Japanese knotweed, and did their answer leave anything uncertain?
Investigation
Was further investigation appropriate — asking a surveyor specifically about knotweed, for instance, or obtaining specialist advice?
Neighbouring land
Was there knotweed on or near adjoining land, and was the risk of it spreading onto the property considered?
Selling and remortgaging
Was the possible effect on a future sale, a remortgage or the market for the property addressed?
These are examples of issues addressed in historical conveyancing material, not a checklist of what every purchaser should have been told. What mattered in an individual purchase depended on the circumstances and on what was known at the time.
So even if your mortgage completed — or there is nothing unusual in your lender’s historical requirements — it can still be worth talking to us about what happened.
Could this problem have been seen coming?
This isn’t about looking at the purchase with hindsight. The important question is what was known — or could reasonably have been identified — when you bought.
What did the seller disclose? What did the survey or valuation show? What was in the conveyancing file? What were mortgage lenders requiring at the time? What kinds of knotweed issues were conveyancing firms addressing with homebuyers? And what were you actually told?
Taken together, that can help build a picture of whether the problem you are facing today was already something that should have been considered when you bought.
Did you receive the right advice?
What the historical evidence can tell us
Where the relevant lender and period are covered, we may be able to establish what that lender’s conveyancing requirements said when you bought, and how that compared with the wider record at the time.
- That does not by itself establish that anyone was negligent, or that you have a claim. Those questions need the original file and legal advice.
- A lender with no express wording on the issue has not thereby accepted it. Silence in the record has to be read carefully, not treated as approval.
- What your conveyancer had to tell your lender and what they had to tell you are different questions, and the second depends on the retainer and the circumstances.
Time limits apply, and in some cases the date on which you first knew enough about the problem matters as well as the date you bought — which is why we ask about both. Our full methodology, including how we treat gaps in the record, is set out in the archive and its limits. Where a solicitor later needs formal historical evidence, Lexsure can provide source-evidenced historical lender information.
Sources and review
Current-problem guidance on this page is reviewed against RICS, Japanese knotweed and residential property, 1st edition, reissued as a professional standard October 2022.
Historical lender information is drawn from Lexsure’s archive of lender-specific conveyancing requirements, maintained since April 2007. Figures on this page state the population they are drawn from.