Survey finding
Extension without planning consent: what to do
Extensions built without planning permission are common on older UK housing. This page covers the enforcement clock, Certificate of Lawfulness, and indemnity insurance.
Last updated: 6 May 2026. Editorially reviewed: 20 May 2026.
Finding
Extension without planning consent
What this usually means
An extension built without planning permission can be either: (a) under permitted development rights (PD) and so didn't need permission; (b) needed permission and went ahead without it; or (c) built before 1948 when planning didn't apply. Local authority enforcement is time-limited, generally 4 years for unauthorised building works (extending to 10 years under the Levelling Up and Regeneration Act 2023 in some cases), after which a Certificate of Lawfulness can be obtained.
Why it matters
Lenders typically require evidence of planning compliance, either the original consent, evidence the works were under PD, or a Certificate of Lawfulness. Indemnity insurance is the common fallback where evidence is absent. The 4-year/10-year enforcement clock matters: if the extension is recent, indemnity may not be available.
Ask your surveyor
- Check:Does the extension look professionally built and does it match the original property?
- Check:Are there visible signs of structural issues or non-compliance with current Building Regs?
Ask the seller
- Check:Was planning permission obtained for the extension?
- Check:Is there a Building Regulations completion certificate?
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
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- Roof issues
- Timber decay
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- Non-standard construction
- Asbestos containing materials
- Roof covering needs repair
- Single skin wall construction
- Timber decay / wet rot
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- Party wall matters
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- Subsidence monitoring
- Full electrical rewire needed
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- EWS1 form required
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- Structural crack BRE category 4-5
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- Chimney flashing failure
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- Cold roof inadequate ventilation
- Warm roof insulation issues
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- Large panel system (LPS) construction
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- Dry rot (Serpula lacrymans)
- Woodworm
- Timber floor springiness
- Cellar / basement damp
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- Aluminium wiring
- Partial rewire needed
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- Back boiler
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- Lead paint
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- Asbestos floor tiles
- Asbestos cement roof
- Asbestos insulated board (AIB)
- Asbestos soffit boards
- Pointing / repointing needed
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- Flat roof membrane condition
- Zinc roof
- Felt roof condition
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- External wall insulation issues
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- Certificate of lawfulness needed
- Indemnity insurance required
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- 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
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- Reema construction
- Unity or Boot construction
- Laing Easiform
- Cornish Unit house
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- Missing or inadequate fire alarms
- Single staircase: means of escape
- No earthing or bonding
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What you need to know
Severity
Significant. Specialist follow-up usually warranted before exchange.
Typical cost to fix
Certificate of Lawfulness application: £206 (England) plus drawings and supporting evidence £500–£1,500. Retrospective planning application £206–£500 plus design fees. Indemnity insurance £150–£600 one-off where time-barred.
Mortgage impact
Most mainstream lenders accept retrospective consent or Certificate of Lawfulness. Indemnity insurance is widely accepted where the extension is time-barred from enforcement. Lenders are more cautious where the extension is recent or where Building Regulations approval is also missing.
Insurance impact
Indemnity insurance covers enforcement risk where the extension is time-barred but unauthorised.
When to pull out
Pull out if a recent unauthorised extension cannot be regularised, indemnity is unavailable, and the lender refuses.
When to renegotiate, and by how much
Ask the seller to obtain Certificate of Lawfulness or fund indemnity insurance. Not typically a price-renegotiation item unless the works are also defective.
Thinking of pulling out or renegotiating? What to do after a bad survey
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Flood, subsidence, EPC, crime, schools, transport, broadband, tenure, age, listed status and price checks where data is available.
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No planning permission for extension , often sits near extension without planning consent 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.