Building Regulations Completion Certificate Guide for London Homeowners

A Building Regulations completion certificate (also called a completion notice) is issued by a Building Control body — either the local authority or an approved inspector — confirming that building work has been inspected and meets Building Regulations requirements.

It is not the same as planning permission. Planning permission controls whether something can be built. Building Regulations control how it is built — structural safety, fire safety, thermal performance, drainage, and more.

A completion certificate is required for any building work that falls within the scope of Building Regulations. This includes:

• Extensions (single-storey, double-storey, loft conversions)
• Conversions (garage to habitable space, basement, house to flats)
• Structural alterations (removing walls, installing steel beams)
• New electrical installations or significant alterations
• New or replacement heating installations (gas, heat pump)
• Replacement windows and doors in certain circumstances
• New bathrooms and kitchens where drainage or structural work is involved
• Roofing work affecting the thermal performance of the building

It is NOT required for minor repairs and maintenance, like-for-like replacement of roofing tiles, or cosmetic work.

Building control inspections happen at key stages during construction:

1. Commencement notice: Notifying Building Control before work starts
2. Foundation stage: Inspection before concrete is poured
3. Damp-proof course stage: Before the DPC is covered
4. Structural frame stage: Before any structural elements are concealed
5. First-fix stage: Electrics and plumbing before plastering
6. Drainage stage: Before drainage systems are backfilled
7. Final inspection: On completion of all works

The inspector may visit all or some of these stages depending on the nature of the work. At final inspection, they confirm all works meet the relevant regulations and issue the completion certificate.

Building control work can be overseen by either:

Local authority Building Control (LABC): The council's building control service. Applications are submitted to the council, and inspectors employed by the council carry out the inspections. The council issues the completion certificate.

Approved inspectors (now Registered Building Control Approvers after 2024 reforms): Private companies approved to carry out building control. They compete with local authority building control. Well-known approved inspectors include NHBC, Premier Guarantee, and many regional firms.

Both routes produce a legally valid completion certificate. The choice is usually made by the contractor or the homeowner at the start of the project.

When selling: Solicitors on both sides will ask for completion certificates for any structural or notifiable work carried out since 1985. Missing certificates can delay or derail a sale. Buyers' solicitors will raise a requisition and the sale will not progress until it is resolved.

For mortgage purposes: Many mortgage lenders require evidence of Building Regulations compliance for material alterations. A missing certificate can affect remortgaging as well as sale.

For insurance: Building insurers expect works to have been carried out in accordance with Building Regulations. Work without a completion certificate may affect a claim.

For safety: The practical purpose of Building Regulations is to ensure building work is safe. A completion certificate is evidence that an independent inspector has checked the work. Work without a certificate has not been independently verified.

Missing completion certificates are common, particularly for older works on London properties. Options include:

Option 1: Apply to the local authority for a regularisation certificate If the work was done after 11 November 1985 and was notifiable under the regulations at the time, you can apply to the local authority for a regularisation certificate. An inspector will assess the existing work. If it complies, a certificate is issued retrospectively. If it doesn't comply, remedial works may be required.

This is not available through approved inspectors — only through the local authority.

Option 2: Indemnity insurance For property sales, it is common practice to purchase an indemnity insurance policy covering the absence of a Building Regulations completion certificate. The seller typically pays.

The policy does not confirm the work is compliant — it protects against any financial loss arising from enforcement action. Lenders and solicitors generally accept this for older works or minor alterations. It is less acceptable for recent structural work.

Important: Do not contact the local authority if you intend to use indemnity insurance — contact invalidates the insurance.

Option 3: Structural/technical report A structural engineer or building surveyor can assess the existing work and produce a report confirming it appears to meet the relevant standards. This can accompany an indemnity policy to strengthen the position in a sale.

Option 4: Regularisation for work not yet covered If work is ongoing or recently completed and inspections were not arranged, contact Building Control immediately. Inspectors can often carry out retrospective inspections if the work is accessible. It is much easier to get a certificate for recent work than for work done 20 years ago.

If you are selling a London property and your solicitor has identified a missing completion certificate:

1. Identify what work was done and when
2. Determine whether it is notifiable under the regulations that applied at the time
3. If yes: consider regularisation (for recent or accessible work) or indemnity insurance (for older work)
4. Get quotes for indemnity insurance — costs typically range from £200 to £800 for residential properties depending on the value and nature of the work
5. If significant structural work is involved, a structural engineer's report will help support the indemnity insurance

rcbGroup registers all notifiable works with Building Control before they start and manages the inspection process throughout the project. At handover, we provide the homeowner with the completion certificate as part of the project documentation pack.

This matters commercially as well as practically — a building work project managed by a principal contractor with full Building Regulations sign-off is significantly easier to sell than one assembled through informal routes without proper inspection records.

If you are considering works on your London home, we can advise on what requires Building Regulations approval and ensure the full process is managed correctly from the start.