Survey finding
Knotweed treatment history: what to check
The IBG is the document that decides the mortgage. This page covers the practical position.
Last updated: .
Finding
Knotweed treatment history
What this usually means
Even with treatment underway, lenders look for an insurance-backed guarantee from a Property Care Association member. Without one, mortgage availability is restricted regardless of how thoroughly the seller has treated the infestation.
Why it matters
The IBG is the document mortgage and insurance both want.
Ask your surveyor
- Check:Is the knotweed within 7 metres?
- Check:Is treatment underway?
Ask the seller
- Check:Is there a PCA-member-backed plan with IBG?
- Check:What stage is treatment at?
Next steps
- •Get two written quotes from local trades before negotiating with the seller.
- •Speak to your mortgage broker before exchanging if the finding affects mortgageability.
Tool shortcut
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What you need to know
Severity
Serious. Lender and insurer involvement likely; structural or specialist remediation.
Typical cost to fix
PCA management plan £3,000-£8,000 over 3-5 years. Excavation £8,000-£15,000.
Mortgage impact
IBG required by most lenders within 7 metres.
Insurance impact
Some insurers add knotweed exclusions.
When to pull out
Pull out if no IBG can be obtained.
When to renegotiate, and by how much
If proceeding without IBG: 5-15% reduction.
Thinking of pulling out or renegotiating? What to do after a bad survey
Run the check on this address
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
Free preview: flood risk, EPC rating, crime, tenure and air quality. The £9.99 report adds the remaining 17 checks, 22 in all, drawing on up to 15 public datasets.
Run a free previewRead next
Japanese knotweed when buying a house , the full buyer guide behind this finding rather than the one line a surveyor writes about it.
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How MyPropertyScan produces this guide, and what it is not
Published by MyPropertyScan and written by Ziad Nasr, who is accountable for its accuracy. No page here is written or reviewed by a chartered surveyor, conveyancer or regulated adviser, and we do not claim otherwise.
This page is not:
- Chartered surveying: we do not inspect properties or produce RICS Home Survey reports
- Legal advice: we do not act as conveyancers or advise on title, tenure or contracts
- Mortgage or insurance advice: we are not regulated by the FCA and give no recommendations
Figures and process steps come from the published UK datasets and standards listed on this page, not from professional practice. Pages are updated when source coverage, survey cost assumptions, or lender and legal requirements materially change. Dataset limitations are set out on the methodology page.
Spotted something out of date or wrong? Email [email protected] and we will correct it and change the update date.
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.
- Professional standard: RICS Home Survey StandardRICS standard for condition-based residential surveys in the UK.
- Learn more from: RICS consumer guide to surveysConsumer-facing guide to survey types and when each level is appropriate.
- Official guidance: GOV.UK buying or selling your homeGovernment overview of the home buying and selling process.