Building Control Completion Certificates: What They Are and Why They Matter

Quick Answer: A Building Control completion certificate is the document issued at the end of a building project confirming that the work complies, as far as can be ascertained, with the Building Regulations 2010. It is issued by the body that supervised the work — either the local authority Building Control or a private Building Control Approver (formerly an Approved Inspector) registered with the Building Safety Regulator. It is not the same as approval at the start of a job: approval (a building notice or full plans application) authorises work to begin, while the completion certificate confirms the finished work passed inspection.

Summary

Almost every conveyancing solicitor in England and Wales will ask for Building Control completion certificates when a property is sold. For a tradesperson, the completion certificate is the paperwork that proves your work was signed off — and its absence can stall a sale, trigger a price reduction, or land your former client with a demand for retrospective regularisation years later. Understanding how and when these certificates are issued protects both you and your customer.

The process matters because notifiable building work that is carried out without Building Control involvement is, in plain terms, unauthorised. There is no time limit after which unauthorised work becomes "legal" simply by age — the enforcement window for prosecution is limited, but the work remains non-compliant and the lack of a certificate follows the property forever. The fix for already-completed unauthorised work is a regularisation certificate, applied for retrospectively, which usually involves opening up finished work for inspection.

A common misconception is that planning permission and Building Regulations are the same thing — they are entirely separate regimes. Planning controls what you may build and how it looks; Building Regulations control how it is built (structure, fire safety, energy, drainage, ventilation, access). You can have full planning permission and still be in breach of Building Regulations, and vice versa. Another frequent error is assuming that a Competent Person Scheme self-certification (FENSA, NICEIC, Gas Safe) is a Building Control completion certificate — it is a separate but equivalent route that produces its own compliance certificate without involving the local authority directly.

Key Facts

• Legal basis — The Building Regulations 2010 (SI 2010/2214) and the Building Act 1984 govern the regime in England. Wales has its own Building Regulations 2010 (Wales) following devolution in 2012.
• Two supervising bodies — Work is overseen either by your local authority Building Control department, or by a private Building Control Approver (the term that replaced "Approved Inspector" under the Building Safety Act 2022 from 1 October 2023).
• Approval ≠ completion — A building notice or full plans approval lets work start; the completion certificate is issued only after the final inspection passes.
• Building notice vs full plans — A building notice is a simpler, faster route for straightforward domestic work; a full plans application submits detailed drawings for approval before work starts and is required for more complex projects.
• Regularisation certificate — The retrospective route for work already completed without Building Control approval. Applied for under Regulation 18 of the Building Regulations 2010.
• No statute of limitations on non-compliance — Local authorities historically could not bring enforcement (prosecution) more than a limited period after completion, but the work stays unauthorised and uncertified indefinitely.
• Conveyancing trigger — Solicitors routinely demand completion certificates for any notifiable work (extensions, structural alterations, new windows, electrical work, replacement boilers) carried out in roughly the last 10-15 years.
• Competent Person Schemes — FENSA/CERTASS (windows), Gas Safe (gas), Part P schemes such as NICEIC/NAPIT/ELECSA (electrical) self-certify work and issue their own compliance certificate, bypassing direct LA notification.
• Inspection stages — Typical inspections include: commencement, foundation excavation, foundation concrete, oversite/DPC, drains, before covering structural elements, and final/completion.
• Indemnity insurance — Where a certificate is missing and the work is old, conveyancers sometimes accept a one-off indemnity policy instead of regularisation — but this does not make the work compliant; it only covers the buyer against enforcement loss.
• Energy efficiency — Completion of certain works also triggers a requirement for an updated EPC or a Building Regulations compliance notice on energy performance.
• Higher-risk buildings — Under the Building Safety Act 2022, higher-risk buildings (generally 18m+ or 7+ storeys with residential use) follow a separate gateway regime overseen by the Building Safety Regulator, not standard Building Control.

Quick Reference Table

Detailed Guidance

When a completion certificate is required

Notifiable building work needs Building Control involvement and therefore produces a completion certificate (or, via a Competent Person Scheme, an equivalent compliance certificate). Common notifiable work includes: extensions and loft conversions, structural alterations such as removing a load-bearing wall or installing a steel beam, underpinning, new or altered drainage, replacement windows and doors, new boilers and heating systems, most fixed electrical work, new bathrooms involving new drainage, and changes of use. Non-notifiable work — like decorating, replacing like-for-like sanitaryware on existing pipework, or minor repairs — does not require a certificate. See [building control](/knowledge/compliance/building-control) for a job-by-job breakdown.

The inspection sequence

On a typical domestic extension, the inspector attends at defined stages and cannot sign off a stage that has already been covered up. This is why timing site visits around the inspector's availability matters to your programme. If you backfill a foundation or board over a steel before it is inspected, you may be asked to open it up again at your cost. Keep a record (photos, dated notes) of each inspection booked and passed — it protects you if a dispute arises later.

Regularisation for unauthorised work

If work was done without notification — by a previous owner, a previous trade, or in error — the lawful way to put it right is a regularisation application to the local authority. The LA will want to inspect, which frequently means exposing structure (lifting floors, opening up around beams). They may require remedial work to bring it up to standard before issuing the certificate. Regularisation is only available from the local authority, not a private Building Control Approver, and only applies to work carried out after a cut-off date set in the regulations (work from November 1985 onwards is generally eligible).

Building Control Approvers and the Building Safety Act 2022

Since 1 October 2023, the role formerly called "Approved Inspector" is now the "Building Control Approver" and individuals working in Building Control must be registered as "Registered Building Inspectors" with the Building Safety Regulator. For most domestic and standard commercial work the practical process is unchanged — you still get a completion certificate at the end — but the terminology on the paperwork has changed, and clients may see references to the new bodies.

Competent Person Schemes — the self-certification route

For specific trades, registered installers can self-certify their own work against the relevant Approved Document and notify Building Control on the customer's behalf, without a Building Control inspector attending. The scheme then issues a compliance certificate that serves the same conveyancing purpose as a completion certificate. Examples: FENSA or CERTASS for replacement windows and external doors (Part L and Part B), Gas Safe registration for gas appliances (Part J/L), and Part P-authorised schemes such as NICEIC, NAPIT or ELECSA for notifiable electrical work. See [part p notifications](/knowledge/compliance/part-p-notifications) for what counts as notifiable electrical work.

Frequently Asked Questions

Is a completion certificate the same as planning permission?

No. They are separate consents under separate law. Planning permission controls whether you can build and what it looks like; the Building Regulations completion certificate confirms how it was built meets technical standards. A project can need both, one, or neither.

What happens if there's no completion certificate when a house is sold?

The buyer's solicitor will flag it. The seller can apply for a regularisation certificate (which may mean opening up the work for inspection), take out an indemnity insurance policy, or renegotiate the price. Indemnity insurance covers financial loss from enforcement but does not make the work compliant.

Can old unauthorised work ever become "legal" just by being old?

The work does not become compliant with age. There is a limited window in which the local authority can prosecute for the breach, but the absence of a certificate and the non-compliance persist and will surface at every future sale.

Who issues the certificate — the council or a private inspector?

Either. You can use your local authority Building Control, or appoint a private Building Control Approver (formerly Approved Inspector). Both issue completion certificates. Only the local authority can issue a regularisation certificate for already-completed work.

Does a FENSA certificate count instead?

For replacement windows and external doors, yes — a FENSA or CERTASS certificate is the recognised compliance document and conveyancers accept it in place of a Building Control completion certificate for that work.

Regulations & Standards

• Building Regulations 2010 (SI 2010/2214) — the core technical and procedural regime in England; sets out notification, inspection and certification requirements.

• Building Act 1984 — primary legislation underpinning the Building Regulations and Building Control enforcement powers.

• Building Safety Act 2022 — introduced the Building Safety Regulator, renamed Approved Inspectors to Building Control Approvers, and created the higher-risk building gateway regime.

• Regulation 18, Building Regulations 2010 — provides for regularisation certificates for unauthorised work.

• Approved Documents A–S — the technical guidance (structure, fire, drainage, energy, ventilation, access, etc.) against which compliance is assessed.

• Part P (Approved Document P) — electrical safety in dwellings; basis for Competent Person electrical self-certification.

• The Building (Approved Inspectors etc.) Regulations — historic framework for private inspectors, now updated under the Building Safety Act regime.

• Building Regulations 2010 (legislation.gov.uk) — full text of the regulations

• Building Act 1984 (legislation.gov.uk) — primary legislation

• GOV.UK: Building regulations approval — official guidance on notices, approval and completion

• Building Safety Act 2022 (legislation.gov.uk) — the Act creating the Building Safety Regulator

• HSE: The Building Safety Regulator — role of the regulator and registered building inspectors

• building control — when Building Control sign-off is needed, job by job

• part p notifications — which electrical work is notifiable and self-certifiable

• quoting tips — how to scope notifiable work correctly in a quote

• insurance — indemnity and liability cover for tradespeople