Glossary
Completion certificate
A completion certificate (or final certificate) is issued by Building Control when it is satisfied that completed work meets the Building Regulations, as far as it has been able to ascertain. Lenders, buyers and insurers often ask for it after extensions and loft conversions.
Keep the certificate with your property records. If work was never signed off, a regularisation application may be possible.
Scotland issues a completion certificate under the building warrant system. Wales and NI have parallel final-certificate processes.
Official source: Building Regulations completion certificates (GOV.UK). Checked 27 October 2026.