Building Control Inspections: What Happens and When

Building Control inspections are the site visits your Building Control body (local authority or a private approved inspector) carries out at defined stages of notifiable work, to check it complies with the Building Regulations before it gets covered up or finished. The direct answer to "when do they happen": at specific structural milestones, not just once at the end — which is exactly the point, since many things (foundations, damp-proofing, structural steel) can't be checked once they're buried or plastered over.

Typical inspection stages

The exact stages depend on the project, but for a typical extension or structural alteration, common inspection points include:

• Commencement — notifying Building Control before work starts (this is what a building notice or full plans approval formally does).
• Foundations excavated — checked before concrete is poured, since foundation depth and ground conditions can't be verified afterwards.
• Damp-proof course — checked before it's built over.
• Drainage — often checked before pipework is backfilled.
• Structural elements — such as steel beams (see our guide to removing a load-bearing wall) checked before they're boxed in or plastered over.
• Pre-plaster — insulation, fire-stopping and first-fix work checked before plasterboard goes up.
• Final inspection — the completed work is checked as a whole before the completion certificate is issued.

Who books the inspections?

In practice, your builder or contractor typically books each inspection at the right stage, since they know when the work has reached that point — this is one of the practical reasons it's worth using a contractor experienced with Building Control processes rather than trying to coordinate it yourself as a homeowner.

What if an inspection fails?

If an inspector finds something that doesn't comply, they'll typically explain what needs to change and you (or your builder) address it before the next stage proceeds — it's a normal, fairly routine part of the process rather than a dramatic outcome, provided issues are fixed properly.

Full plans vs building notice — does it change the inspections?

Both routes lead to the same site inspections; the difference is mainly in when the design gets checked. A full plans application has drawings checked and approved before work starts, while a building notice allows work to start with less upfront paperwork but the same inspections happen as work progresses. See our Building Regulations explained guide for the fuller comparison, and what approval typically costs either way.

What if you use an approved inspector instead of the council?

The inspection stages themselves are broadly the same whether you use your local authority's Building Control service or a private approved inspector — both are carrying out the same statutory checks under the same regulations. The main practical difference tends to be responsiveness and scheduling flexibility, which is one reason some contractors prefer working with a specific approved inspector on larger projects.

Typical inspection outcomes

Most inspections on a well-managed project are straightforward pass-throughs — the inspector checks the relevant element, confirms it's correct, and the project moves to the next stage. Genuine problems are relatively uncommon on projects using experienced, Building-Control-familiar contractors, which is part of why choosing a contractor with a track record of compliant work is worth the extra scrutiny at the quoting stage.

Common mistakes

• Covering up work before the relevant inspection. This is one of the most common (and expensive) mistakes — if foundations or drainage get covered before being checked, the inspector may require it to be exposed again.
• Not booking inspections with enough notice. Most Building Control bodies need at least 24-48 hours' notice for a site visit — leave a buffer in your project schedule.
• Assuming "no news is good news." If you haven't heard from Building Control in a while, check in — don't assume silence means approval.

Related reading: fire safety building regulations.