A building regulations completion certificate is the piece of paper that proves your extension, loft conversion or structural alteration was inspected and signed off as compliant with the Building Regulations. It sounds like a formality, yet in 2026 it is one of the first documents a buyer’s solicitor, a mortgage lender or an insurer will ask to see. Without it, a sale can stall, a remortgage can be refused and you can be left paying for indemnity insurance or a retrospective “regularisation” application. This guide explains what a building regulations completion certificate is, who issues it, how long it takes, what to do if yours is missing, and how a suitably qualified, accredited surveyor can help you fix the problem before it costs you a sale.
A building regulations completion certificate is a formal document issued by a building control body after the final inspection of a project. It confirms that, so far as the inspector could reasonably ascertain, the completed work complies with the applicable requirements of the Building Regulations. It is separate from planning permission: planning says you may build; the completion certificate says the work was built correctly.
The legal basis in England and Wales is Regulation 17 of the Building Regulations 2010. A local authority must issue a certificate once it has been notified that work is complete and has been able to satisfy itself, “after taking all reasonable steps”, that the relevant requirements have been met. Crucially, Regulation 17(4) states that the certificate is evidence – but not conclusive evidence – that those requirements were complied with. That single clause is why experienced conveyancers still recommend a proper building survey even where paperwork is in order.
The wording depends on who supervised the work. If your local authority building control team inspected the job, you receive a completion certificate. If you used a private building control provider, you receive a final certificate instead, and the provider notifies the council so the work is recorded on the council’s register. Since the Building Safety Act reforms, private providers in England and Wales are known as Registered Building Control Approvers (RBCAs) rather than “approved inspectors”, and individual inspectors must be Registered Building Inspectors. Both documents do the same job in a conveyancing file.
Most structural, thermal, fire-safety, drainage and electrical work is “building work” under the regulations. Common domestic examples that should end with a certificate include:
Some of this work – windows, boilers, electrics, cavity insulation – can be self-certified under a government-approved competent person scheme such as FENSA or Gas Safe. In those cases the installer registers the work and you receive a scheme certificate rather than a council one. It has the same status for conveyancing purposes, so keep it safe.
The route depends on the type of application you (or your builder) made before work started. The table below summarises the options in England for non-higher-risk buildings, based on current GOV.UK and Planning Portal guidance.
| Route | Who inspects | Typical timing | What you receive |
|---|---|---|---|
| Full plans application | Local authority building control | Decision within 5 weeks (or 2 months by agreement); certificate usually within 8 weeks of completion | Completion certificate |
| Building notice | Local authority building control | Work can start 2 days after notice; certificate after final inspection | Completion certificate (no formal plan approval) |
| Initial notice via an RBCA | Registered Building Control Approver | Agreed with the approver; final inspection at completion | Final certificate (copied to the council) |
| Competent person scheme | Registered installer self-certifies | Installer notifies the scheme, usually within 30 days | Scheme certificate (e.g. FENSA, Gas Safe) |
| Regularisation | Local authority only | Inspection, possible opening-up and remedial works, then decision | Regularisation certificate (retrospective) |
There is no separate fee for the certificate itself – it is included in the building control charge you paid with your application. Local authorities set their own charges based on the type of work, number of inspections and floor area, while RBCAs negotiate fees directly. What does cost extra is doing things in the wrong order. Regularisation applications typically attract a premium over the standard charge, and you may also have to pay for opening-up works, a structural engineer’s report or remedial work before a certificate is granted. Copies of an existing certificate are cheap by comparison: many councils charge a modest administration fee, often in the region of £30–£40 including VAT.
This is the situation that generates most of the searches for this topic, and it usually surfaces at the worst possible time – when a buyer’s solicitor raises an enquiry or a lender’s valuer notes an extension with no paperwork. You have three realistic options, and a fourth that supports all of them.
If the work was inspected but the paperwork has gone astray, contact the building control body that supervised it. Councils keep a register of completion certificates and can usually supply a copy for an administration fee; your conveyancer can often obtain it through the council’s online systems. If an approved inspector or RBCA was used, ask them for a copy of the initial notice and final certificate. The HomeOwners Alliance notes that before 2013 councils were not required to issue completion certificates in every case, so for older work a “final inspection letter” may be all that exists – and that is normally acceptable to lenders.
Regularisation is retrospective approval for work carried out without consent on or after 11 November 1985. According to the Planning Portal, the council will inspect the work to determine whether it complies, and “exposure, removal and/or rectification” may be required to prove it. Only a local authority can grant regularisation – an RBCA cannot – and councils commonly limit applications to work under roughly 10–15 years old. It is the only route that gives you a genuine certificate, which is why it is the best option if you are not selling imminently or if the buyer’s lender refuses indemnity cover.
If timing is tight, a one-off indemnity policy arranged by a conveyancer protects the buyer (and their lender) against the cost of enforcement action. The HomeOwners Alliance puts typical premiums at around £20–£300 depending on the property value – for example roughly £175 on a £500,000 home. Two warnings: the policy usually cannot be taken out until 12 months after the work was completed, and it is invalidated if anyone contacts the council about the missing certificate. It also insures against enforcement, not against the work being defective. Our guide to when to use indemnity insurance explains the trade-offs in more detail.
Whichever route you choose, the underlying question is the same: is the work actually sound? An indemnity policy does not fix a sagging steel or an unsupported chimney breast, and a regularisation application goes far more smoothly if you already know what the inspector will find. A specific defect report on the unsigned-off element, or a full Level 3 building survey for buyers, gives you evidence-based answers. Where a structural alteration is involved, a structural engineer’s report with calculations is often exactly what building control will ask for.
| Option | Best for | Indicative cost | Main drawback |
|---|---|---|---|
| Copy of existing certificate | Work that was inspected; paperwork lost | Council admin fee (often c. £30–£40) | Only works if an inspection actually happened |
| Regularisation certificate | Unauthorised work after 11 Nov 1985; not selling immediately | Premium on standard charge plus any opening-up and remedial works | Time, disruption and possible remedial costs |
| Indemnity insurance | Imminent sale; work over 12 months old | Typically £20–£300 | Void if the council is contacted; does not cover defects |
| Independent surveyor inspection | Any of the above – buyers and sellers | From a few hundred pounds for a specific defect report | Not a certificate in itself, but the evidence behind one |
Yes, but expect friction. A buyer can proceed without a certificate, and most lenders will accept an indemnity policy or a satisfactory regularisation certificate. Some lenders, however, will not lend on a property where a significant structural alteration has no paperwork at all, and a cautious buyer may negotiate a price reduction or retention. In practice the seller who arrives with a copy certificate, a recent survey of the works and – where needed – a structural engineer’s letter is in a far stronger position than one who simply offers to pay for indemnity insurance. For buyers, our article on suing a builder for poor workmanship explains your remedies if unsigned-off work turns out to be defective.
Building control has been reshaped by the Building Safety Act 2022, and 2026 is a milestone year:
The direction of travel is clear: more documentation, named dutyholders, and a firmer expectation that completion evidence exists. Homeowners who commission work in 2026 should treat the completion certificate as a deliverable in the building contract, not an afterthought. Our building regulations guide and permitted development rights 2026 guide cover the wider framework.
Building control inspectors check compliance at fixed points; they do not act for you, and they will not tell a buyer whether an extension is well built. A suitably qualified, accredited surveyor – regulated or accredited by bodies such as RICS, CIOB or RPSA – fills that gap. Typical instructions include:
Choosing the right professional matters: anyone can call themselves a surveyor, so always confirm accreditation and professional indemnity insurance. Our guide to what a building surveyor does explains the qualifications to look for.
Whether you are a buyer who has just discovered an unsigned-off extension, a seller facing a solicitor’s enquiry, or a homeowner planning work in 2026, Survey Merchant makes it straightforward to get the right expert on the case:
Ready to resolve a missing certificate or plan a compliant project? Explore our building surveying services or contact our team for a fast, no-obligation quote from an accredited surveyor.
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