What Happens If You Don't Comply with Building Regs?

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

Last reviewed: March 2026

This isn't about scaring you. It's what actually happens when jobs are done off-regs or half-certified - on site, at sale, and with insurers and solicitors in the mix.

Enforcement notices - who gets hit first

Councils enforce under the Building Act. If they think the work doesn't comply, they can serve:

• A notice to remove or alter non-compliant work.
• It goes to the owner, because they own the building. Then the owner comes looking for you.

What it looks like in practice:

• Letter saying "this work doesn't comply with X, do Y by Z date".
• If the owner ignores it, the council can do the work themselves and bill the owner. The owner then chases you for the cost.
• There's no magic time-out on dangerous work - if something is clearly unsafe, they can still go after it years later.

Prosecution - rare, but ugly when it happens

Councils can prosecute for:

• Carrying out building work that doesn't comply.
• Ignoring enforcement notices.

Reality:

• Full prosecutions are rare on domestic jobs - councils don't want the hassle unless you're being wilfully stupid or dangerous.
• But when they do go for it, fines can stack, and you get a criminal record on top of the cost of fixing the work.
• If you're the builder who keeps ignoring notices, expect to move up their priority list.

What happens at sale

This is where most non-compliance gets found.

Typical pattern

Buyer's surveyor spots:

• Loft conversion with no paperwork.
• Knock-through with no calcs/completion cert.
• Window/boiler/stove with no proper certs.

Solicitors ask for: completion certificate, Part P/Gas Safe/FENSA/HETAS paperwork.

If it's missing, you get:

• Price chips ("we'll knock off £20k to cover the risk").
• Buyers walking away.
• Mortgage lenders refusing the loan or requiring regularisation/indemnity.

You might never hear about it - but the owner remembers who did the work when they're sitting in a solicitor's office being told their house is "non-compliant".

Regularisation - late, messy and not cheap

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

Reality for the owner (and you)

• Fees are higher than a normal application - think hundreds, often £400-£800+ depending on the job and council.
• BC will want to:
  • Inspect as much as they can.
  • See calcs, specs, test certificates (structure, electrics, gas, etc.).
  • Often ask for opening up (more below).
• They can refuse to regularise if they can't verify the work or if it's too far off current standards.
• Everyone then looks at the builder and asks why it wasn't notified and built right first time.

The "opening up" problem

If BC didn't see the work at the time, they can't just take your word for it later.

So they say:

• "We need to see the beam bearings." → open ceilings/walls.
• "We need to see the drains." → lift floors, dig trial holes.
• "We need to see insulation/fire-stopping." → cut into plasterboard.

At that point:

• Owner pays to open up and make good.
• If they're pointing at your contract, it's your time and money.
• Opening up is always more painful and more expensive than just letting BC see it at the right time.

Insurance - where it bites

Non-compliant or undocumented work can cause headaches like:

• Buildings insurance - if a claim is linked to dodgy work (e.g. collapse, fire, water damage), insurers will dig into whether it was built and certified properly. They may reduce or refuse payouts if things are clearly off-regs.
• Professional indemnity / public liability - if you're sued for defective work, your PI/PL insurer will want to see that you acted competently and followed the regs. Systematic corner-cutting is not a good look when they're deciding whether to back you.

Again, no drama if you've generally done things by the book. Big drama if your default is "we don't bother with Building Control on small jobs".

Reputation damage - the bit no one writes down

You live off referrals.

If your jobs routinely leave owners with:

• No completion cert.
• No electrical/gas/windows certs.
• Work that surveyors and BC keep flagging as non-compliant.

Then over a few years you become "the builder the agents tell buyers to avoid".

You won't see an official letter about that - you'll just feel it in how many decent jobs you get offered.

Time limits - 12 months vs "no time limit"

Two different clocks to know:

• 12-month limit for prosecution - councils generally have 12 months from when the work finished to bring a criminal prosecution under the Building Act.
• No hard limit for unsafe work - they (and owners) can still require dangerous work to be fixed years later via enforcement routes and civil claims.

So "it's been a few years, they can't do anything now" is half-true at best. Prosecution might be off the table; costly remedial work very much isn't.

Common car-crash scenarios

A few you've probably seen already:

Undocumented loft conversion found at sale

• No BC record, no completion cert, no structural calcs.
• Surveyor flags; lender gets twitchy.
• Owner pays for: engineer, regularisation, opening up, remedial work - and possibly lives with a reduced valuation.

Knock-through with no calcs or BC

• Beam taken off "builder's eye".
• Cracks appear or surveyor spots it.
• Owner ends up paying for engineer, steel check, possible strengthening, and regularisation.

Electrical work with no certs

• Full rewire "done by a mate", no Part P notification.
• Buyer's solicitor demands Part P cert or regularisation; BC may require testing, some opening up, and remedial work to current standards.

Removed chimney breast with no visible support

• Ground floor breast gone, stack still up there, no steel or gallows brackets.
• Surveyor calls it out as a structural risk; BC and an engineer get involved.
• Owner pays to put in retrospective support, and decorate all over again.

In every one of these, the owner starts by ringing the builder and asking "why wasn't this done properly?".

Bottom line: doing it right once is cheaper than doing it twice with a solicitor watching.

When in doubt, notify the job and get Building Control in early. A clean set of certs and a completion certificate are worth more to your reputation than whatever you saved by skipping them.

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.

How this site is funded →

Spotted something wrong or out of date? Email us at hello@kilnguides.co.uk.

In crisis? Samaritans 116 123 · Mental health support

How this site is funded →