Can I sell a house with Japanese knotweed?

Yes. With a professional management plan and an insurance-backed guarantee in place, many lenders will lend and an ordinary sale is possible. Without one, mortgage buyers tend to fall away at survey, and the realistic routes are treating it first or selling to a cash buyer who prices the knotweed in from the start.

Do I have to tell buyers about Japanese knotweed?

Yes — the TA6 property information form asks about it directly, and knowingly giving a wrong answer can let the buyer sue you after completion. Answer it honestly with your solicitor's guidance. Selling to a buyer who purchases in full knowledge of the knotweed is what closes the door on that risk.

Will a mortgage lender accept a house with knotweed?

It depends on the RICS category. Categories A and B call for specialist advice and typically a mortgage retention until a management plan from a Property Care Association member, backed by an insurance-backed guarantee, is in place. Categories C and D generally don't block lending.

Japanese knotweed

The survey said knotweed. The buyer said nothing — and vanished. Here's what actually sells.

A plant in the garden shouldn't sink a sale, but the word does: retention, category, guarantee, and a form you can be sued over. Here's what each of those really means — and the one kind of sale that can't come back to bite you afterwards.

A or Bthe RICS categories that trigger specialist advice and a mortgage retention — C and D generally don't block lending (HomeOwners Alliance)

3–5 yearshow long professional treatment programmes typically run — the sale doesn't have to wait that long, but the paperwork matters

£950+herbicide treatment from about £950 for a small stand; excavation from around £4,000 — before the guarantee that lenders actually want

What the surveyor's letter actually means

Tap each number. The plant is the smallest part of the problem — the paperwork around it is what stalls sales.

1The plant, and the letter it gets

The surveyor assigns a RICS category. A ("significant impact, action required") and B ("potentially significant impact") both call for specialist advice and typically a mortgage retention — the lender holds back money until the problem is professionally in hand. C and D generally don't block lending at all. Most vanished buyers were sitting on an A or a B and a lender who wouldn't move.

2Distance, spread and the retention

What worries a valuer isn't the leaves — it's proximity to the house and where the rhizomes might be heading. That judgement drives the category, the category drives the retention, and the retention is what actually kills the mortgage: your buyer suddenly needs thousands they don't have, for a plant in someone else's garden. They don't negotiate. They evaporate.

3The paper the lender actually wants

Not the plant gone — the risk managed. A treatment plan delivered by a Property Care Association member, carrying an insurance-backed guarantee, is what turns "no" into "yes" for many lenders. Programmes run three to five years, but a sale doesn't have to wait for the last spray: the plan and the guarantee transfer, and that's what the next lender reads.

4The form with legal teeth

The TA6 asks about knotweed directly, and a knowingly wrong answer can get you sued after completion — this is the fear that keeps sellers up at night, and it's rational. The answer is not creative form-filling; it's the opposite. Disclose fully, with your solicitor guiding the form, to a buyer who purchases in full knowledge. A buyer who knew everything has nothing to come back with.

Sources: HomeOwners Alliance, Japanese knotweed guide · Property Solvers, unmortgageable property types. General information, not legal advice — your solicitor guides the TA6, not us. Last reviewed August 2026.

Your three honest routes

Two of them can get you full market value. We're the one that gets you a date.

Treat it, paper it, sell normally

A PCA-member treatment plan with an insurance-backed guarantee reopens mortgage lending for many buyers — and the plan transfers with the house, so you can sell once it's in place rather than waiting out the full programme. If you have months and the category is B or below, this is the full-value route.

From about £950 for herbicide treatment of a small stand, from around £4,000 for excavation, plus the guarantee — and a marketing period where some buyers will still flinch at the word.

Sell disclosed on the open market

Knotweed properties do sell to ordinary buyers, especially at category C or D, or with treatment already under way. Price it realistically, disclose fully on the TA6, and expect the survey to reopen the negotiation once the buyer's lender reads the report.

The renegotiation-at-survey risk is the story of this route: the price you accept in week one is not reliably the price you complete at in week twelve — and a retention can still surface late and take the buyer with it.

Sell to us, knotweed and all

We buy at any category, without a lender, so there's no retention and no renegotiation. Tell us everything — category, treatment history, the neighbour's garden — and the offer is made in full knowledge, which is exactly what closes the door on being sued later. You pick the completion date.

The price is below market value — 65–82% depending on the date you choose, judged against what the house would fetch with the knotweed priced in, and shown before you give us anything.

The certain route: no lender to flinch, a figure that can't shrink at survey, and a purchase made knowing everything you know.

The disclosure question, answered straight

Let's say the quiet part clearly: we will never help anyone soften, shade or sidestep the TA6. Not because we're saints — because a concealed defect is a lawsuit with your name on it, and because our whole model depends on knowing the truth before we price. Tell us everything, including the things you're worried about: disclosed facts cannot move our figure later — that's the price promise — and a buyer who bought in full knowledge has no misrepresentation claim to bring. The knotweed stopped being a legal risk the day you stopped being the only one who knew about it.

One honest exclusion: if there's live litigation over the knotweed — a claim with a neighbour about encroachment, in either direction — nobody can promise you a completion date, including us. Resolve the claim first; then we can talk dates.

The questions knotweed sellers ask

My buyer's lender wanted a "retention". What is that?

The lender agrees the mortgage but holds back part of it — often thousands — until the knotweed has a professional management plan in place. Your buyer has to fund the gap themselves, which most can't or won't. It's the single most common way a knotweed sale dies, and it's why categories A and B lose buyers even when the buyer personally didn't mind the plant.

It's coming from next door. Why is it my problem?

Unfairly, encroachment doesn't change the survey: the category reflects where the knotweed is relative to your house, not whose garden it started in. You may have a claim against the neighbour — that's a solicitor conversation — but be aware that live litigation makes any dated sale impossible until it's resolved. Many owners settle for a treatment plan that covers both sides of the fence.

If I treat it, is it actually gone?

Treat "gone" with caution — programmes run three to five years, and what lenders rely on isn't the word "eradicated", it's the insurance-backed guarantee standing behind the work. That's also the honest answer to "should I just cut it down and say nothing": no. It regrows, the TA6 asks anyway, and concealment converts a gardening problem into a legal one.

Will you really not lower the offer when you see it?

The offer is made after you've told us the category, the spread and the history — so there's nothing left for a survey to "discover". If our survey finds the knotweed is what you said it was, the figure stands. The only thing that changes a figure after acceptance is something material you knew and didn't tell us — which is exactly why telling us everything protects you.

Get an offer made in full knowledge

There's no obligation and nothing to sign. We'll give you a figure in writing, with our reasoning, and you can take it to anyone you like before you decide.

Or call us: 0191 249 3969 · 8am–8pm, seven days