Building Control: How It Actually Works (Step by Step)

‍‌‌​‌​‌‌‌‌​‌​​‌​‌‌​‌​​​​​​​​​‌​‌​‍For small builders and main contractors (England)

Last reviewed: March 2026

This isn't "what is Building Control?" - you already know that. This is how the system actually runs so you can work with it, not fight it and then get stitched up when the client tries to sell.

Building Notice vs Full Plans

You've basically got two routes in for most domestic jobs.

Full Plans application

Use this when:

• Job is complex (loft, big extension, HMO/flat conversion, structural gymnastics).
• Client is picky.
• You want fewer arguments on site.

Pros:

• You submit drawings, calcs and specs. BC check them and issue a plans approval/conditional approval.
• Once approved, you've got a paper trail: "build this and you're good".
• Fewer nasty surprises on site - most issues get picked up at design stage.

Cons:

• Slower up front.
• More design work needed before you start.

Building Notice

Use this when:

• Straightforward domestic work (simple single-storey extension, basic knock-through, small jobs).
• You know what you're doing and are happy to sort details on site.

Pros:

• Faster to start - you give notice, pay the fee, and crack on.
• Less paperwork up front.

Cons:

• No approved plans to fall back on.
• BC will sort compliance on site - if they don't like something, you're changing it at your cost.
• Risky if architect's drawings are vague or client keeps changing their mind.

Blunt version:

If it's anything beyond "bread and butter", Full Plans makes your life easier.

If you're using Building Notice, assume BC can (and will) ask you to prove compliance as you go.

What inspections to expect (and when)

Typical domestic job (extension/loft/new build):

1. Start / first visit - you call them when you begin. They'll want to meet, understand the job, and maybe look at existing structure.
2. Foundations - before you pour. They'll check depth, width, ground conditions, and anything near trees/sewers.
3. Damp-proof course / oversite - DPC height, cavity trays, hardcore, insulation and DPM before you cover.
4. Drainage - pipes laid, falls, manholes, connections, before backfilling. Sometimes tested in their presence.
5. Pre-plaster / first fix - structure, insulation, fire-stopping, stairs, services routing, ventilation provisions, before boarding and skimming.
6. Pre-completion - second fix done, alarms fitted, stairs/guarding in place, ventilation/Part L bits close to finished.
7. Final inspection - everything done, paperwork ready (air test, SAP, certificates, test sheets).

You don't have to drag them out for every tiny thing, but if you cover something that matters (foundations, drains, structure, fire-stopping, insulation) without them seeing it, you're asking for trouble.

What BC actually care about

Stuff they'll dig into:

• Structure - beams, bearing, foundations, roof structure.
• Fire - escape routes, doors, compartmentation, alarms, fire-stopping.
• Damp and drainage - DPC/DPM, cavities, drains, drainage fields.
• Energy - insulation thickness, airtightness, Part L evidence.
• Ventilation - fans, trickle vents, free areas.
• Access and safety - stairs, guarding, thresholds, safety glazing.

Stuff they often gloss over (but you're still liable for):

• Cosmetic finishes (unless they hide defects).
• Minor layout tweaks that don't affect structure/fire/services.
• Perfect alignment with the architect's pretty visuals - they're there for regs, not interior design.

Important: a BC officer not commenting on something doesn't make it compliant. If you cut the corner, it's still on you.

Completion certificate - why it matters

What it is

A short letter from BC saying "we've inspected, and as far as we can see, this work meets the Building Regulations".

Why it matters

Solicitors, surveyors and lenders expect it when the client sells or remortgages.

Without it, you're into:

• Price chips.
• Indemnity policies.
• Regularisation (open-up works, extra fees).

If you walk away without a completion certificate, that loose end will come back with your name on it when the client needs paperwork and can't find it.

Your move

• Don't let the job "fade out".
• Book the final inspection.
• Chase the certificate and keep a copy with your records.

Local Authority BC vs Approved Inspectors

You've got two main flavours:

Local Authority Building Control (LABC)

• Statutory, can't refuse to deal with you.
• Good on enforcement, HMO/licensing crossover, tricky existing conditions.
• Sometimes slower, sometimes more conservative - varies by council.

Approved Inspectors / Registered Building Control Approvers

• Private outfits, can be more flexible and responsive.
• You/your client appoint them; they notify the council with an initial notice.
• Can decline work or fire you if you're a nightmare.

For most small domestic jobs either is fine.

• Go LA if there's lots of enforcement/licensing/history involved.
• Go AI if you want quicker responses and you've built a relationship with a good one.

Failing an inspection - what actually happens

It's not instant court and handcuffs.

Typical pattern

1. Inspector flags a problem (e.g. shallow foundations, missing insulation, no fire-stopping).
2. They'll tell you what's wrong and what they expect - sometimes they'll follow up in writing.
3. You fix it, they come back, sign it off.

Where it gets ugly

• You ignore them and keep building.
• You cover defects hoping they won't notice later.
• You argue instead of asking "what do you want to see to sign this off?"

If something's a genuine judgement call, you can:

• Ask them to show you the relevant part of the Approved Document.
• Get your engineer/architect to write a short justification.

But if it's obviously wrong (no bearing, no insulation, no fire-stopping) - just fix it.

Competent Person Schemes and BC

A lot of jobs don't go through BC directly because they're signed off by schemes instead.

Common ones

• Gas Safe - gas appliances, flues, some heating work.
• NICEIC / NAPIT / similar - electrical work under Part P.
• FENSA / CERTASS / similar - replacement windows/doors.
• HETAS - solid fuel appliances.
• OFTEC - oil-fired heating.
• MCS + CPS - renewables (PV, heat pumps etc.).

If a registered installer does the work, they notify Building Control via their scheme and issue the certificate.

Key points for you

• The work is still Building Regs work - it's just being signed off through a different route.
• If your mate "who isn't registered any more" does the boiler/rewire/windows, it's back on you and Building Control.
• Keep copies of all CPS certificates - they'll be asked for at sale.

Common builder mistakes with Building Control

Stuff that keeps coming back to bite:

Not notifying at all

"We'll sort it later" turns into no completion cert and a horrible regularisation process.

Assuming the architect has sorted everything

Designers submit plans; you still need to notify start, book inspections and build what's drawn.

Covering up before inspection

Pouring foundations, backfilling drains, boarding ceilings, closing cavities without BC seeing them.

This is how you end up opening finished work to prove what you did.

Changing structure/services on the fly

Moving beams, stairs, walls, boilers, drains "to suit on site" without telling the designer/BC - you've just invalidated their approval.

Thinking a passed inspection = a clean bill of health forever

BC don't see every detail. If you've cut corners, a surveyor can still flag it years later.

Regularisation - the expensive back door

When work was done without Building Regs, and the client now needs paperwork, the usual route is a regularisation application to the local authority.

What that looks like

• Higher fee than a normal application.
• BC will inspect as much as they can after the fact - and often ask for opening up:
  • Lift floors.
  • Open ceilings.
  • Expose foundations/drains.
• If they're happy after inspection and any remedial works, they issue a regularisation certificate (not quite the same as a timely completion cert, but better than nothing).

Why it's always worse than doing it right first time

• More disruptive - finished work gets ripped apart.
• More expensive - you pay the fee and the remedial work.
• You turn up as "the builder who didn't bother with regs" when everyone reads the file.

When in doubt, pick up the phone: call your local Building Control or your usual Approved Inspector before you start. A quick chat and a clean paper trail beats arguing with a surveyor and a solicitor five years later.

This page is a general guide for small builders and main contractors working on dwellings in England. It doesn't cover every edge case or non-domestic job. Always check the latest Approved Documents, your drawings/spec, planning conditions and Building Control before you start cutting or pouring. SiteKiln does not provide legal, financial or tax advice. All content is for general information purposes only. Always seek professional advice for your specific situation.

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