A building regulations completion certificate is the formal written confirmation from your local authority building control (or an approved inspector) that the completed building work has been inspected and meets the requirements of the Building Regulations 2010. For any significant building work — including extensions, loft conversions, structural alterations, and new dwellings — a completion certificate is one of the most important documents a homeowner can hold.

This guide explains what a completion certificate is, when you need one, what happens if you have built without one, and how to obtain a regularisation certificate retrospectively.

What Is a Building Regulations Completion Certificate?

When you notify a local authority building control (LABC) or an approved inspector of building work and submit a building notice or full plans application, inspectors visit the site at key stages to check compliance with the Building Regulations. Once the work is complete, a final inspection is carried out and — if satisfactory — a completion certificate is issued.

The completion certificate confirms:

• The building work was carried out under the relevant approval reference
• The work has been inspected at key stages
• The work substantially complies with the Building Regulations

Under the Building Act 1984 (as amended), local authorities are legally required to issue a completion certificate within 8 weeks of the final inspection for most types of building work, provided the work complies.

When Do You Need a Completion Certificate?

A completion certificate is required for any building work that is subject to building regulations approval. This includes:

• House extensions (any size — there is no size threshold for building regulations compliance)
• Loft conversions
• Garage conversions to habitable use
• New dwellings
• Structural alterations (e.g., removing load-bearing walls)
• New or altered drainage
• Electrical installation work (Part P — certain notifiable works)
• Replacing a heating system
• Installing new windows and doors (where energy efficiency compliance is required)

Why Does a Completion Certificate Matter When Selling?

When you sell a property, your solicitor will raise enquiries about any building work carried out during your ownership (and sometimes before). The buyer’s solicitor will ask for:

• Planning permission documentation (decision notice and approved plans)
• Building regulations completion certificates

If a completion certificate cannot be provided for notifiable building work, the sale may be delayed or fall through. The buyer’s mortgage lender may also refuse to lend against a property with unresolved building works compliance.

In practice, missing completion certificates are one of the most common issues discovered in conveyancing searches and can cost significant time and money to resolve at the point of sale — when you have the least negotiating leverage.

What If I Don’t Have a Completion Certificate?

Regularisation Certificate

If building work was carried out without building regulations approval, or if approval was obtained but the final inspection was never carried out and a completion certificate was never issued, you can apply for a regularisation certificate from the local authority building control.

The regularisation process involves:

• Making a regularisation application to the LABC with a description of the work carried out
• The inspector assessing what can be verified from visible elements
• Opening up work (lifting floors, removing plaster) to expose and inspect structural elements, insulation, and drainage that cannot be seen
• Carrying out any remedial work required to bring the construction up to the standard required
• Issuing a regularisation certificate once the work is satisfactory

Regularisation is more expensive and disruptive than obtaining approval at the time of construction because opening-up works are required. The regularisation certificate does not retrospectively certify that the work was compliant at the time it was built — it certifies that it has been inspected and is now acceptable.

Indemnity Insurance

Where regularisation is not possible or practical (for example, for minor work carried out many years ago), indemnity insurance can be used to satisfy a buyer and their mortgage lender. The policy indemnifies against the risk that the local authority takes enforcement action. Premiums are typically £100–£400 for a single-payment policy on a standard domestic extension.

Indemnity insurance is a workaround rather than a solution — it does not confirm the work was done correctly, merely that enforcement action is unlikely. Buyers should be made aware that insured work has not been confirmed compliant.

How Long Does It Take to Get a Completion Certificate?

Once the final inspection is satisfactorily completed, a completion certificate should be issued within 8 weeks by the local authority. In practice, most are issued within 2–4 weeks of the final inspection. Approved inspectors typically issue completion certificates faster than LABC.

Frequently Asked Questions

Is a building regulations completion certificate the same as planning permission?

No — these are entirely separate documents from separate regulatory systems. Planning permission (from the planning department) governs what can be built and its external appearance. Building regulations approval (from building control) governs how it must be built to meet safety, structural, and thermal standards. Both may be required for an extension project, and both sets of documentation should be retained.

Can I request a copy of a completion certificate if I’ve lost mine?

Yes — contact the local authority building control department with the property address and approximate date of the works. They should hold records and can usually issue a copy for a small administrative fee (typically £25–£75). Records for work carried out before electronic systems were common may be harder to trace.

What is an initial notice (approved inspector)?

Instead of using LABC, homeowners can appoint an approved inspector to carry out building control. The approved inspector registers an “initial notice” with the local authority, carries out inspections, and issues a “final certificate” (equivalent to a completion certificate) when the work is complete. Both initial notice and final certificate should be retained and provided when selling.

Does a completion certificate guarantee the work is defect-free?

No — a completion certificate confirms that the building control officer was satisfied the work complied with building regulations at the time of inspection. It does not constitute a guarantee of quality or workmanship, and it does not mean the building is free from defects. For workmanship guarantees, you need your contractor’s warranty and, for structural work, professional indemnity insurance from the design team.

What happens if my contractor did not notify building control?

The legal obligation to notify building control rests with the “person carrying out the work” — in practice, the builder, although the homeowner is ultimately responsible. If your contractor failed to notify building control, you should apply for regularisation before selling. Do not assume the problem will go away — it will surface in conveyancing.

Keep Your Building Regulations Records Safe

Crown Architecture & Structural Engineering manages building regulations submissions and liaises with building control throughout the construction process, ensuring completion certificates are obtained and provided to clients. We can also advise on regularisation and retrospective approval for works carried out without proper certification.

Call 07443804841 or complete the enquiry form above to discuss your situation.