Survey finding
Japanese knotweed flagged in your survey
Japanese knotweed has a reputation that often runs ahead of the actual risk on a given property. The legal and lending position is what makes it a serious item. This page explains what to expect on the mortgage side, what a management plan looks like, and the right questions for the seller.
Last updated: 6 May 2026. Editorially reviewed: 20 May 2026.
Finding
Japanese knotweed
What this usually means
Japanese knotweed is a non-native invasive plant that spreads through underground rhizomes. It is regulated in the UK and listed on standard property forms (the seller's TA6 form has a specific question about it). Its mere presence on or near a property does not always cause physical damage, but it routinely affects mortgage decisions.
Why it matters
Many UK lenders will require a professional management plan with an insurance-backed guarantee before lending on a property with knotweed on or close to it. That can affect both your purchase and any future sale. The risk also depends on how close the stand is to the buildings.
Ask your surveyor
- Check:How close is the stand to the property and to neighbouring boundaries, and what category of risk would you place it in?
- Check:Has the stand been treated, and if so do you have evidence of an active management plan and remaining treatment period?
Ask the seller
- Check:Have you completed the TA6 form question on Japanese knotweed, and are you aware of any historic stands on or near the property?
- Check:Do you have a current management plan with an insurance-backed guarantee from a PCA-accredited specialist?
Next steps
- •Speak to your mortgage broker before going further, ask whether the lender will accept the property with knotweed and what documentation they need.
- •If a management plan exists, ask for the original plan, the guarantee, and the remaining treatment schedule in writing.
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Browse all findings
- Spray foam insulation
- Evidence of movement
- Damp
- Japanese knotweed
- Damp proof course issues
- Underpinning
- Cracks
- Roof issues
- Timber decay
- Electrical issues
- Non-standard construction
- Asbestos containing materials
- Roof covering needs repair
- Single skin wall construction
- Timber decay / wet rot
- Settlement cracks
- RAAC concrete
- Wall tie failure
- Party wall matters
- Drainage issues
- Subsidence monitoring
- Full electrical rewire needed
- Flat roof condition
- Cladding issues
- EWS1 form required
- Lintel failure
- Structural crack BRE category 3
- Structural crack BRE category 4-5
- Chimney stack movement
- Chimney flashing failure
- Parapet wall movement
- Bay window cracking
- Flat roof ponding
- Cold roof inadequate ventilation
- Warm roof insulation issues
- Prefab concrete construction
- Large panel system (LPS) construction
- Rising damp
- Penetrating damp
- Condensation vs damp distinction
- Dry rot (Serpula lacrymans)
- Woodworm
- Timber floor springiness
- Cellar / basement damp
- Outdated electrics (60-amp fuse board)
- Aluminium wiring
- Partial rewire needed
- Gas boiler condition
- Back boiler
- Unvented hot water cylinder issues
- Lead pipes (pre-1970)
- Lead paint
- Asbestos in Artex ceilings
- Asbestos floor tiles
- Asbestos cement roof
- Asbestos insulated board (AIB)
- Asbestos soffit boards
- Pointing / repointing needed
- Render cracking
- Pebbledash delamination
- UPVC window seal failure
- Sash window condition
- Flat roof membrane condition
- Zinc roof
- Felt roof condition
- Corrugated asbestos roof
- Cavity wall insulation issues
- External wall insulation issues
- No building regulations certificate
- No planning permission for extension
- Certificate of lawfulness needed
- Indemnity insurance required
- Neighbour dispute on file
- EPC F or G rating
- Oil heating property
- Off-gas-grid property
- Solar panel lease vs owned
- Ground source heat pump property
- Air source heat pump property
- Chimney breast removed without support
- Floor joist decay
- Wall bowing
- Mould and condensation
- Septic tank property
- Thatched roof condition
- Listed building restrictions
- Conservation area restrictions
- Restrictive covenants on title
- Coal mining area
- Coastal erosion risk
- Flood risk zone 3
- Radon affected area
- Contaminated land history
- Trees near building
- Party wall agreement outstanding
- EICR required
- Knotweed treatment history
- Single glazing condition
- RCD protection missing
- Damp-proofing guarantee transferability
- PRC (precast reinforced concrete) house
- Airey house
- BISF (British Iron and Steel Federation) house
- Timber frame construction
- Steel frame house
- Wet rot
- Heave (ground movement)
- Chimney condition and stability
- Short lease (under 80 years)
- Fire safety: flat and leasehold issues
- Blocked or condemned flue
- Spalling brickwork
- Diagonal cracks in walls
- Retaining wall condition
- Tanking failure in basement
- Missing or slipped ridge tiles
- Lead flashing condition
- Gutters and downpipes
- Double glazing condensation (failed units)
- Skylight or roof light condition
- Dormer condition and weathering
- Torn or missing sarking felt
- Chancel repair liability
- Easement or right of way
- Boundary dispute or unclear boundary
- Adverse possession risk
- Flying freehold
- Ground rent escalation clause
- High or variable service charge
- Extension without planning consent
- Loft conversion: no building regs
- Single-phase electrical supply only
- Shared or private sewer
- Blocked or collapsed drains
- Cesspit or septic tank
- Solid fuel heating
- No mains gas supply
- Low water pressure
- Private water supply
- Wimpey No-Fines concrete house
- Reema construction
- Unity or Boot construction
- Laing Easiform
- Cornish Unit house
- Cross-wall construction
- In-situ concrete construction
- Oak frame construction
- Radon: mitigation required
- Missing or inadequate fire alarms
- Single staircase: means of escape
- No earthing or bonding
Tool shortcut
Check the property before you offer
Flood, subsidence, EPC, crime, schools, transport, broadband, tenure, age, listed status and price checks where data is available.
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The Survey Decoder explains the wording. The full report adds address-specific flood, subsidence, EPC, crime, listed status, building age and price comparison data, so a single finding isn't judged in isolation.
Run the check
Check the property before you offer
Flood, subsidence, EPC, crime, schools, transport, broadband, tenure, age, listed status and price checks where data is available.
Run a free previewRead next
Knotweed treatment history , often sits near japanese knotweed on a survey and is the next thing to check.
Editorial review
Editorial owner: BiteRight Ltd, operator of MyPropertyScan. We review buyer guides against UK public property datasets, RICS survey wording, lender requirements, and common buyer questions.
Pages are updated when source coverage, property-risk guidance, survey cost assumptions, or product checks materially change. Methodology and dataset limitations are explained on the MyPropertyScan methodology page.
Sources used
We use UK public and specialist sources where they are available. Public datasets can be incomplete, delayed, or missing for some addresses. Treat them as a starting point, not as a replacement for professional advice.
Source standard: preference goes to official government datasets, statutory bodies, professional standards, and primary dataset publishers. We cite the source family on the page and explain coverage limits rather than filling gaps with unsupported estimates.