What is the difference between a Completion Certificate and a Final Certificate for building control in London?

Final Certificate is the term used by Local Authority Building Control (LABC) for the completion sign-off document. Completion Certificate is the term used by Approved Inspectors (private building control bodies) under the Building (Approved Inspectors etc.) Regulations 2010. Both serve the same legal function — confirming the works have been inspected and comply with Building Regulations — and are equally accepted by conveyancing solicitors and mortgage lenders.

How long does a final building control inspection take in London?

The final inspection visit itself typically takes 1–2 hours for a loft conversion or extension. Scheduling time varies by borough and Approved Inspector workload — LABC inspectors in busy London boroughs may have a 2–5 day lead time for a final inspection appointment. The certificate is typically issued within 2–4 weeks of the satisfactory final inspection, once the inspector has processed the paperwork and confirmed all certificates have been received.

Can I sell my house without a Building Regulations Completion Certificate in London?

You can proceed with a sale without a Completion Certificate, but the buyer's solicitor will raise an enquiry and may require indemnity insurance or a retrospective regularisation. Indemnity insurance is available for extensions where the LPA and building control body are not aware of the works — once either has been notified, indemnity insurance is no longer available. For completed works where building control was involved but no final inspection was obtained, contact LABC directly about a retrospective final inspection.

What is a Building Regulations Indemnity Insurance policy for an extension in London?

Building Regulations indemnity insurance is a one-off premium insurance policy that indemnifies the buyer (and their lender) against loss arising from the LPA or LABC taking enforcement action due to works carried out without Building Regulations approval or without a final completion certificate. For a single-storey extension, premiums range from £100–£300 for £500,000 indemnity. For a loft conversion or double-storey extension, premiums range from £200–£600. The policy cannot be obtained if LABC or the Approved Inspector has already been notified and is aware of the works.

Building Control Completion Certificate London 2025 | Final Sign-Off Process

How Do I Get a Building Control Completion Certificate in London?

To get a Building Control Completion Certificate in London, notify your building control body (LABC or Approved Inspector) when the work is complete, pay any outstanding inspection fees, and arrange a final inspection visit. If the inspector is satisfied that the work complies with Building Regulations, they issue a Completion Certificate (Approved Inspector) or a Final Certificate (LABC). This certificate is required for conveyancing on property sale and by most mortgage lenders.

Building control final inspection: what is inspected and how to prepare

The building control completion process in London involves a series of statutory inspections throughout the construction programme (foundations, oversite, damp proof course, structural frame, first fix, insulation, drainage) culminating in a final completion inspection when all works are finished. The final inspection covers: structural completion (all specified structural elements built as approved — steel beams, joist hangers, padstones, lintel sizes); thermal insulation (all insulation installed to specified U-values, air test completed if required under Part L); fire safety (mains-wired smoke alarms installed and tested, fire doors installed to correct specification, escape windows at correct size, any fire-rated partitions or downstand beams to specification); drainage (foul and surface water drainage tested — CCTV survey may be requested for new drainage runs); electrical installation (Part P electrical certificate from a registered electrician, or a building control electrical inspection); mechanical ventilation (if an MVHR or mechanical extract ventilation is part of the approved scheme); and accessible design (where the works are required to meet Part M accessibility requirements). To prepare for the final inspection: compile all certificates and test reports (EPC assessment if required, electrical completion certificate, air permeability test results, CCTV drainage survey reports, window energy ratings, any third-party specialist certificates); ensure the inspector can access all areas of the completed works (loft, roof void, undercroft, drainage inspection chambers); confirm all structural tie-ins are complete (joist hangers fully nailed, straps installed, padstones bedded); and check that all fire doors are correctly labelled with the FD30/FD60 designation and the CE mark. The inspector will compare completed works against the approved drawings — any deviations must be retrospectively documented or remedied before the certificate is issued.

What happens without a Completion Certificate and how to get a retrospective one in London

Failing to obtain a Building Control Completion Certificate is a common issue on London properties, particularly on extensions and loft conversions built in the 1990s–2010s before conveyancers routinely required building control sign-off. The consequences of missing building control completion include: problems on sale — the buyer's solicitor will raise an enquiry about any extensions or structural alterations. Without a Completion Certificate, the solicitor will require either an indemnity insurance policy or a building control regularisation application. Property sale delays — obtaining retrospective building control approval can add 4–12 weeks to a transaction; indemnity insurance for a structural extension is available but typically requires the works to be fully completed (not partially completed or clearly non-compliant). Mortgage complications — some lenders require a Completion Certificate for extensions above a threshold floor area (typically 20m² GIA or above) and will decline to lend on a property where significant extensions lack sign-off. Regularisation: if an extension or loft conversion was built without building control approval or without obtaining a final inspection, a Regularisation Application can be submitted to LABC (not to an Approved Inspector — Approved Inspectors cannot regularise works carried out without their supervision). LABC will undertake an initial assessment and specify what opening-up works are needed to verify concealed structural, thermal, and drainage elements. The regularisation fee is 150% of the standard plan check and inspection fee — typically £900–£2,400 for a loft conversion or extension in London. After opening-up and inspection, if the works are found to comply (or non-compliances are remedied), LABC issues a Regularisation Certificate. If the works were carried out under an Approved Inspector who was never informed of completion, the Approved Inspector can be re-engaged for a late completion inspection — provided the work is accessible and their approved drawings are still current. Builderr's project management service includes close-out management: we track the inspection schedule, request and obtain the final inspection, compile the sign-off pack, and deliver the Completion Certificate to the homeowner.