Building control inspections are the practical mechanism by which England’s Building Regulations are enforced on site. They are not optional and not merely bureaucratic box-ticking — they exist because failures in structural, drainage, fire, and thermal standards are expensive or catastrophic to correct after walls are plastered and floors are laid. Understanding when inspections happen, who carries them out, and what they cover helps you manage your build without delays or enforcement notices.
Who Carries Out Inspections?
There are two routes to building control in England and Wales:
Local Authority Building Control (LABC): Provided by your local council. Fees vary by authority and project type. Applications are made directly to the council, and their surveyors carry out site inspections. They are a public body with statutory powers.
Registered Building Control Approver (RBCA, formerly Approved Inspector): A private body registered with the Building Safety Regulator. They provide the same statutory approval function but operate commercially. Notable examples include NHBC (for new homes), Assent, and Local Authority Building Control’s partner scheme. Since the Building Safety Act 2022, the terminology has changed from “Approved Inspector” to “Registered Building Control Approver,” but the function is the same.
For most domestic work, either route is valid. Cost and turnaround time for decisions vary — a private RBCA is sometimes faster on complex projects, but LABC is the default for most householders.
Notifiable vs. Exempt Work
Not all work needs Building Regs approval. Exempt work (Schedule 2 of the Building Regs 2010) includes:
- Most repairs and like-for-like replacements (subject to exceptions)
- Small detached outbuildings under 30 m² (with some conditions)
- Small porches under 30 m² at ground level with no sanitary facilities
Notifiable work includes: extensions, loft conversions, garage conversions, structural alterations, new drainage, rewiring (unless done under a Part P competent person scheme), new boiler or central heating system, and replacement windows (unless installed by a FENSA/CERTASS registered installer).
If in doubt, contact your LABC before starting work — checking is free, and proceeding without approval when required is a criminal offence.
Application Types
Building Notice (BN): A simpler, faster application. You submit basic information and start work after 48 hours. No plans are formally approved in advance — the inspector visits as work progresses and checks compliance on site. Works well for smaller projects where the builder knows the regs. Risk: if the inspector identifies a non-compliant detail, you may have to alter or demolish work already completed.
Full Plans (FP): You submit detailed drawings and specifications before starting. The council or approver checks the plans and issues an approval notice (target 5–8 weeks for LABC; faster with a private approver). Work can then proceed with confidence that the design is regs-compliant — inspections verify it is being built as designed. Better for complex projects, loft conversions, extensions, or where mortgage lenders require evidence of approved plans.
Regularisation: Applied for retrospectively when work has already been completed without Building Regs approval. The inspector may require invasive opening-up to verify hidden work (e.g., foundations, drainage). Fees are higher and a regularisation certificate (rather than a completion certificate) is issued.
The Inspection Stages
The number and type of inspections varies with project type. For a typical domestic extension or loft conversion, expect the following staged inspections. The builder must notify Building Control before covering up work at each stage.
| Stage | What the inspector checks | Notice required |
|---|---|---|
| Commencement | Site set-out, welfare provisions, notice of start | 2 days before starting |
| Excavation / foundations | Depth and width of strip/raft; soil conditions; any contamination | Before concrete is poured |
| Concrete pour | Concrete specification; foundation thickness; DPC level | During pour or immediately after |
| Damp-proof course (DPC) | DPC height above external ground level (min 150 mm); cavity tray details | Before brickwork above DPC is laid |
| Structural frame (oversite) | Steel beams, padstones, bearing details as designed | Before encasing in masonry or boarding |
| Drainage | Fall, gradient, pipe joints, inspection chamber positions, surcharge test | Before backfilling trenches |
| Floor construction | Insulation, vapour control layer; screed depth | Before screed is poured |
| Roof structure | Trussed rafters or cut roof; bracing; water-tightness | Before tiling or felting |
| Insulation / airtightness | Wall, roof, and floor insulation values; continuity; airtightness measures | Before covering with boards or plaster |
| Completion | Full walkthrough; fire doors; ventilation; electrics (EICR); structural completion | Within 5 days of completion |
For a loft conversion, additional inspections cover the new floor structure, fire-rated ceiling, escape window, and staircase rise-and-going compliance. For a new extension with a flat roof, a drainage test (typically a 30-minute hydraulic surcharge test) will be required.
What Happens If You Miss a Stage?
If you cover up work without notifying Building Control and they have not inspected it, the inspector has the right to require you to open up the work at your own cost so it can be inspected. On a simple foundation, this might mean breaking up concrete; on finished drainage, it means digging up a trench. The cost can run to thousands of pounds.
In practice, experienced surveyors will often accept photographic evidence (time-stamped, showing the work clearly) for stages where opening up is not possible — but this is at their discretion, not your right. Always notify in advance.
Completion Certificate
At the end of the project, once the inspector is satisfied that all work complies, Building Control issues a Completion Certificate. This is an important legal document — retain it with your property’s records.
Without a completion certificate:
- You cannot sell the property without a retrospective regularisation certificate (expensive and disruptive)
- Mortgage lenders and conveyancers will flag the gap in records
- Your home insurer may have grounds to contest claims arising from the works
- If the works were unsafe, your liability is unmitigated
Obtaining the completion certificate is a stage many self-managers neglect. Budget for a final inspection visit and, if required, submit any completion documents (Gas Safe certificate, EICR, window FENSA certs) that the inspector needs before issuing it.
Competent Person Schemes
For certain work — specifically electrical, gas, glazing, and some heating work — registered tradespeople can self-certify compliance without a Building Regs application. Schemes include:
| Scheme | Covers |
|---|---|
| FENSA / CERTASS | Window and door replacement |
| Gas Safe Register | Gas appliances and pipework |
| NAPIT / NICEIC / ECA | Electrical work (Part P) |
| HETAS | Solid fuel heating appliances |
| MCS | Microgeneration (heat pumps, solar PV) |
Work done under these schemes is exempt from a formal Building Regs application, and the installer issues a certificate directly to you and notifies the council’s register. Keep all certificates — they form part of your property’s compliance record.
