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.
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 subsidence signals for a UK address in 15 seconds
BGS clay susceptibility, 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
BGS clay susceptibility, building age, tree context and the things to ask your surveyor.
Run a free previewEditorial 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.