A Building Regulations Completion Certificate is one of the most important documents your property can hold — yet it is routinely missing from title packs on older work, misunderstood by buyers, and sometimes confused with planning permission. This guide explains what it is, how it is obtained, what happens when work was done without it, and the routes available to regularise the position before sale or purchase.
What a Building Regulations Completion Certificate Is — and Why It Matters
Building Regulations approval confirms that construction work complies with statutory minimum standards covering structure, fire safety, energy efficiency, drainage, ventilation, and electrical and gas safety. The Completion Certificate is issued by the Local Authority Building Control (LABC) or an Approved Inspector (now operating as Registered Building Inspectors under the Building Safety Act 2022 framework) once all inspection stages are passed and the work is confirmed complete and compliant.
It matters for three specific reasons:
Conveyancing: Your solicitor will check for a Completion Certificate for any notifiable building work carried out since 1985. If it is absent, they will either require a regularisation certificate, an insurance-backed guarantee, or they will flag the absence to your mortgage lender — any of which can delay or abort the transaction.
Insurance: Some insurers will exclude defects arising from non-compliant work. If a building claim arises from works done without Building Regulations approval, you may find coverage is disputed.
Resale: A buyer's solicitor will raise the same enquiries. Undocumented work does not go away — it becomes a problem at every future transaction until it is regularised.
The Three Application Routes
Full Plans application You submit detailed drawings, specifications, and calculations to Building Control before work starts. They review and approve (or request amendments). Inspections are then carried out at defined stages during construction. This route takes longer to initiate (5–8 weeks for initial approval) but gives you and your contractor certainty about compliance requirements before groundbreaking. Best practice for any significant work.
Building Notice Work can start within 48 hours of submitting a Building Notice. No drawings are submitted in advance — the inspector visits during construction and assesses compliance on site. Faster to initiate, but higher risk: if work does not comply, you may need to expose or redo it. Unsuitable for complex projects and cannot be used for work to properties in a terrace where the Party Wall Act applies, or for certain fire-sensitive buildings.
Regularisation application For work that has already been carried out without Building Regulations approval. You apply retrospectively to your Local Authority (Approved Inspectors cannot accept regularisation applications). The inspector will need to see enough of the work to assess compliance — this may require opening up floors, walls, or ceilings. If work is compliant, a Regularisation Certificate is issued. If not, remedial work must be carried out before the certificate is granted. Regularisation is only available for work carried out after 11 November 1985.
How to Apply
Local Authority Building Control (LABC) Apply online through your local council's planning portal or the Planning Portal (planningportal.co.uk). Most LAs have moved to online applications. You will need to specify the type of work, provide drawings (for Full Plans), and pay the relevant charge.
Approved Inspector / Registered Building Inspector (RBI) Since the Building Safety Act 2022, private sector inspectors are being transitioned to the RBI framework administered by the Building Safety Regulator (BSR). You appoint an RBI directly and they manage the approval and inspection process. Often faster than LABC for straightforward projects. Check the BSR register for accredited RBIs.
Typical application costs (in addition to contractor fees):
| Application type | Typical cost range |
|---|---|
| Building Notice (householder extension) | £200–£500 |
| Full Plans (single-storey extension) | £300–£700 |
| Full Plans (loft conversion) | £400–£800 |
| Regularisation application | £200–£600 |
| Electrical installation certificate (Part P) | £50–£200 |
These are Building Control charges only — structural engineer fees, architect fees, and specialist certifications are additional.
Inspection Stages
For a typical Full Plans project, Building Control will inspect at the following stages:
- Commencement: notified before or within 2 days of work starting
- Foundation excavation: before concrete is poured
- Damp-proof course (DPC) level: before floor slab is laid
- Drainage: before backfilling trenches
- Structural floor/frame: at key structural stages
- Roof structure: before covering
- Insulation: before covering
- Completion: final inspection of all elements including fire doors, ventilation, electrics
Failure to notify Building Control for a mandatory inspection stage can result in you being required to open up work for inspection — an expensive and disruptive remediation.
What Happens If Work Was Done Without a Completion Certificate
Option 1 — Regularisation certificate Apply to the Local Authority as described above. Available for work done after November 1985. Cost: £200–£600 for the application, plus any remedial works required to bring the work up to standard. This is the cleanest solution — you end up with a formal statutory document.
Option 2 — Insurance-backed guarantee (IBG) An IBG is an indemnity insurance policy that protects the current owner and future owners against the cost of Local Authority enforcement action arising from the absence of a completion certificate. A typical policy costs £150–£400 as a one-off premium and is transferable on sale. IBGs are commonly accepted by mortgage lenders and solicitors for older, lower-risk works (e.g. a conservatory built 15 years ago).
However, an IBG does not make non-compliant work compliant — it is an insurance policy against the financial consequences of enforcement, not a certification of compliance. If the work is structurally defective, the IBG covers enforcement costs but not repair costs. Some lenders and solicitors will not accept IBGs for structural works such as extensions, roof alterations, or conversion projects.
Option 3 — No action for enforcement (over-10-year rule) Local Authorities generally cannot take enforcement action for a breach of Building Regulations more than 10 years after the work was completed (under section 36 of the Building Act 1984, as commonly interpreted). This does not mean the issue disappears — you cannot obtain a completion certificate, and a buyer's solicitor will still raise enquiries. But it may support the case for an IBG rather than requiring regularisation.
How Solicitors Check for Completion Certificates
During conveyancing, your solicitor will:
- Request the seller's Property Information Form (TA6), which asks directly about building works and whether consents were obtained
- Raise a specific enquiry for any works visible on the property
- Check Local Authority search results for any planning or building enforcement notices
- Review any certificates or guarantees provided by the seller
Crucially, the Local Authority search (LLC1 and CON29) will show planning permissions but does not automatically confirm that a Completion Certificate was issued. Your solicitor will often need to make a specific enquiry to LABC — or rely on the seller's disclosure.
What to Do If You Can't Find the Certificate for Work Done Before You Owned
This is common on properties that have changed hands multiple times. Your options, in order of preference:
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Contact your Local Authority Building Control: they retain records of applications and inspections. Some LAs can supply copies of completion certificates for a small admin fee (£20–£50). Call or email the LABC team directly and provide the property address and approximate date of works.
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Check the title pack and previous conveyancing files: prior solicitors may have obtained copies or IBGs. Your current solicitor can request these from the seller's solicitor.
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Apply for regularisation: if the work is post-1985 and you can identify what was done, a regularisation application resolves the position permanently.
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Obtain an IBG: if regularisation is not practical (e.g. the work was done in the 1990s and opening up is disproportionate), an IBG is typically the accepted solution.
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Renegotiate the purchase price: if the absent certificate relates to structural work and the seller cannot resolve it, you are entitled to reflect the risk and potential remediation cost in your offer.
Further Reading
- Planning Permission in the UK: A Complete Guide for Homeowners — understanding the difference between planning permission and building regulations approval
- Basement Conversion Costs and Planning UK — building regs requirements for basement conversions, including Full Plans vs Building Notice
- Party Wall Surveyor Costs UK — party wall awards and building regs are separate but often run concurrently on extension and loft projects
- The Complete UK Renovation Cost Guide 2025 — cost ranges for the works most likely to require building regulations sign-off
- VAT on Renovation Work UK — When You Pay 5% and When You Pay 20% — building regs sign-off can also affect which VAT rate applies; understand the rules before your contractor invoices
- Converting a Garage UK: Planning, Costs and Building Regulations — garage conversions are a common source of missing completion certificates; this guide covers the Full Plans vs Building Notice choice and what the inspector will check
- Radon Gas UK: Testing, Mitigation and Costs — new builds in high-risk areas require radon membranes under Building Regs Part C; the completion certificate should confirm these were installed
- Building Regs Completion Certificate Missing UK: Your Three Options — a step-by-step guide to regularisation, indemnity insurance, and retrospective inspection when the completion certificate cannot be found
- New Build Snagging List UK: What to Check Before Legal Completion — for new builds, the completion certificate confirms Building Regs sign-off; this guide covers how to confirm it is in place as part of your snagging process
- Building Regulations Completion Certificates: Why They Matter — a full walkthrough of which works trigger the need for a completion certificate, the Full Plans vs Building Notice routes, and what to do if the certificate is missing