Survey finding
Category 3 structural cracks: what to do before exchange
Category 3 is the level at which surveyors and lenders take cracking seriously. This page sets out what the classification means, what a structural engineer will look for, and the negotiation playbook.
Last updated: 6 May 2026. Editorially reviewed: 20 May 2026.
Finding
Structural crack BRE category 3
What this usually means
BRE Digest 251 classifies cracks by width and damage. Category 3 means cracks 5-15mm, doors and windows sticking, weather-tightness compromised, repairs that go beyond cosmetic. The cause matters more than the width: clay shrink-swell, leaking drains, tree roots, or wall-tie failure all produce category 3 patterns.
Why it matters
Category 3 is the threshold at which lenders, insurers and surveyors stop treating cracks as cosmetic. A structural engineer's report is the standard next step, and underpinning may or may not be required depending on cause.
Ask your surveyor
- Check:Can you identify the most likely cause of the cracking pattern?
- Check:Is the movement historic and stable, or is there evidence of recent or active progression?
Ask the seller
- Check:Has the property had any insurance claims for subsidence, heave, or settlement?
- Check:Have any structural reports been commissioned in the past, and can you share them?
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
Check subsidence signals for a UK address in 15 seconds
Directional BGS 1:1 million engineering geology, building age, tree context and the things to ask your surveyor.
Run a free previewCross-check this surveyor's flag with BGS clay susceptibility and tree-proximity data for the address.
What you need to know
Severity
Serious. Lender and insurer involvement likely; structural or specialist remediation.
Typical cost to fix
Structural engineer's report £400-£900. Repairs vary widely: localised re-pointing and patching £1,500-£4,000; partial underpinning if movement is active £8,000-£20,000 per affected bay; full underpinning £30,000-£60,000+ for a typical semi.
Mortgage impact
Many lenders will instruct their own valuer to revisit. They may impose a retention until a structural engineer signs off, or require completed works before drawdown.
Insurance impact
Insurers will ask for the engineer's report. If the cause is identified as one-off (e.g. drain leak repaired) cover usually continues at standard rates; if active subsidence, expect specialist insurer placement and a higher premium.
When to pull out
Pull out if the engineer confirms active progressive movement, the seller refuses to engage, and remediation cost approaches 10%+ of the purchase price with no insurance support.
When to renegotiate, and by how much
Negotiate based on the engineer's quoted remediation plus a 15-20% buffer; typical settled outcomes sit at 4-10% off the agreed price.
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 subsidence signals for a UK address in 15 seconds
Directional BGS 1:1 million engineering geology, building age, tree context and the things to ask your surveyor.
Run a free previewHow 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 hello@mypropertyscan.com 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.