Building control and the completion certificate that protects your sale

Planning permission decides whether you can build something. Building regulations decide whether what you build is safe, warm, ventilated and structurally sound — and building control is the process that checks it. The two are entirely separate (we cover the distinction in the planning permission vs building regulations guide); this page goes deeper into the building-control half: how to get sign-off, what gets inspected, and why the completion certificate at the end is the single document most likely to hold up your eventual sale.

Almost every extension, loft conversion, structural alteration, new bathroom, re-wire or replacement boiler is "notifiable" — it needs building control, even when it needs no planning permission at all. Here's how the system runs, in England.

Two routes in: building notice vs full plans

Who carries it out — and a name change to know

Building control can be provided by your local authority's building control team, or by a private-sector approver. Since 6 April 2024, under the Building Safety Act, those private providers are called Registered Building Control Approvers (RBCAs) — the role previously known as the "approved inspector" — and the people who carry out inspections are Registered Building Inspectors. Both routes can sign off a domestic project. One practical difference matters later: only the local authority can issue a regularisation certificate for work that was done without approval.

The inspection stages

Whichever route you choose, the work is inspected at set stages. For a typical extension that means roughly:

• Excavation and foundations — before concrete is poured.
• Damp-proof course and oversite — before the floor goes down.
• Drainage — before backfilling, and again on a water/air test.
• Structure — steel beams, padstones, floor and roof structure, before they're hidden.
• Insulation and weatherproofing — before plastering.
• Completion — the final inspection of the finished work.

The completion certificate — the document that protects your sale

When the finished work complies, building control issues a completion certificate (a final certificate on the private route). It is the proof that the work met the regulations — and it is the document a buyer's solicitor will ask for when you sell. Its absence is one of the most common reasons a sale stalls: no certificate, and you're into a price retention, indemnity insurance, or a scramble to regularise under time pressure. Keep every completion certificate with the property's deeds, alongside your planning permissions.

Competent-person schemes: self-certification for some work

Not everything goes through a building control application. Certain work can be self-certified by a registered "competent person" — replacement windows and doors through FENSA or CERTASS, most domestic electrical work through a registered electrician's scheme, a boiler through Gas Safe. The installer notifies the scheme, and you receive a certificate that does the same job as building control sign-off for that element. When you sell, these certificates are asked for just like a completion certificate — so collect them at the time, because chasing a long-gone contractor years later is painful.

Regularising work done without approval

If notifiable work was carried out without building control — by you or a previous owner — a regularisation certificate is the route to put it right. You apply to the local authority (only they can regularise), pay a regularisation charge, and they assess the work as far as it can be inspected, which can mean opening parts up or carrying out remedial work. It's not automatic, but it's the clean fix, and far cheaper than discovering the gap when a buyer's survey finds it.

How this connects to your Planning Permission Checker report

Building control turns on the construction detail of your specific project, not on the public designations at an address — so it's the half of the system the Planning Permission Checker report deliberately doesn't assess. The report answers the planning question (conservation area, Article 4, listed status); for the building-control and structural side, and for feasibility on anything load-bearing or unusual, enquiries route to Hampstead Chartered Surveyors, an RICS-regulated practice (Firm Reg. 923064).