Phase 8 · Completion · Task 01 of 05
Building Control Final Inspection
How to prepare for the BCO final inspection on your extension. The certificates you need, why sign-off takes months (not weeks), and what to do when trades won't certify.
Prerequisites
Complete these first
Your builder packs up. The last tradesperson leaves site. You assume building control sign-off is a week or two away. It isn't. On real projects, the gap between the builder leaving and the BCO signing off your extension stretches to months. Sometimes over a year. And the delay has nothing to do with the quality of the building work.
It's paperwork. Specifically, certificates from your regulated trades. Until every certificate is sitting in your hand and submitted to building control, the BCO will not visit. The inspection itself takes an hour or two. The certificate chase that precedes it can consume your life.
25 working days
The statutory deadline a Gas Safe registered engineer has to notify your installation after completion (see 25 working days). On one documented UK extension, the engineer breached this and the certificate took 14 months to arrive (kitchen in use late 2022, certificate finally received January 2024). The BCO signed off one day after the certificates were finally submitted. The rule is a hard legal limit, not a soft norm; enforcement is rare but available.
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