Quick answer
Most building work needs building regulations approval, even when planning permission isn’t needed. That includes extensions, loft and garage conversions, removing load-bearing walls, new drainage and most electrical work. In Oxford you can use the council’s building control team or a registered building control approver, and you get a completion certificate when the work passes.
Building regulations set the minimum standards for how building work is done: that it’s structurally sound, safe in a fire, warm, well ventilated and properly drained. They’re separate from planning permission, and most home improvements need them even when planning doesn’t apply. Here’s how they work in Oxford and across Oxfordshire.
What building regulations cover
The regulations are split into parts, each with an approved document that explains how to comply. These are the ones that matter most for home projects:
| Part | What it covers |
|---|---|
| A | Structure: foundations, walls, beams and roofs |
| B | Fire safety, including escape routes from new rooms and fire doors |
| C | Damp, and contaminated ground |
| E | Sound insulation between rooms and homes |
| F | Ventilation |
| G | Water supply, sanitation and hot water safety |
| H | Drainage and waste |
| J | Boilers, stoves and flues |
| K | Stairs, guarding and safety glazing |
| L | Energy efficiency: insulation, windows and heating |
| M | Access to and use of buildings |
| P | Electrical safety in homes |
| O, Q and S | Overheating, security and electric vehicle charging, mainly for new homes |
When you need building regulations approval
| Project | Building regulations approval needed? |
|---|---|
| Extension | Yes |
| Loft conversion | Yes, including the new stairs, fire safety and floor strength |
| Garage conversion | Yes, for the new wall, insulation, ventilation and fire safety |
| Removing a load-bearing wall | Yes, with structural calculations for the new beam |
| New bathroom or kitchen with new drainage | Yes for the drainage. New electrical work is covered by the electrician’s certificate. |
| Replacement windows and doors | Yes, unless the installer is registered with a scheme such as FENSA or Certass, who self-certify |
| New boiler or heating system | Yes, self-certified by a Gas Safe registered engineer |
| Rewiring or new circuits | Yes, self-certified by a registered electrician |
| Re-rendering or recladding a large part of a wall | Often, because it can trigger an insulation upgrade under Part L |
| Garden room under 15 m² with no sleeping accommodation | No |
| Porch or conservatory under 30 m², separated from the house by external doors | Usually no |
| Like-for-like repairs, or replacing kitchen units | No |
If a job is self-certified, the installer registers it and you receive a certificate. Keep it with your house papers.
Who checks the work
You can choose who checks the work:
- Your council’s building control team. In Oxford that is Oxford City Council. Cherwell, West Oxfordshire, South Oxfordshire and Vale of White Horse run their own services.
- A registered building control approver. These are private firms. Since 6 April 2024 they must be registered with the Building Safety Regulator, and they replaced what used to be called approved inspectors.
Both do the same job and issue the same kind of certificate. Each council and approver sets its own fees, so ask for a quote early. For a typical extension or loft conversion it is usually several hundred pounds.
Full plans, building notice or regularisation
| Route | How it works | Best for |
|---|---|---|
| Full plans | Drawings and calculations are checked before work starts. The decision is due within five weeks, or two months if you agree. | Extensions, loft conversions and structural work |
| Building notice | No plans approval. Work can start two working days after the notice. The notice lapses if work hasn’t started within three years. | Small, simple jobs where the builder knows the requirements |
| Regularisation | Retrospective approval for work done without it, carried out on or after 11 November 1985. Some work may need opening up for inspection. | Putting right work that was never approved |
For anything structural, full plans is the safer route. Problems are found on paper, not after the walls are built.
Inspections and the completion certificate
The inspector visits at key stages. For an extension these usually include the foundation excavations, the damp-proof course, the drains, the structure and any steel beams, the insulation before it’s covered, and a final inspection. Your builder books the visits.
When the work passes the final inspection, you receive a completion certificate. Keep it, along with any certificates for electrical, gas and window work. You’ll need them when you sell.
Building regulations and planning permission
| Planning permission | Building regulations | |
|---|---|---|
| What it controls | How the work looks, how it’s used and its effect on neighbours | How the work is built: structure, fire, insulation, ventilation and drainage |
| Who decides | The council’s planning team | Council building control or a registered approver |
| When it is needed | Some projects; many are permitted development | Almost all structural work, conversions and extensions |
| What you get | A decision notice | A completion certificate |
Many projects need both. Our guide to planning permission in Oxford covers the planning side, and our permitted development guide explains what you can build without applying.
What happens if work doesn’t have approval
Breaking the building regulations is a criminal offence. Since 1 October 2023 it can bring an unlimited fine and up to two years in prison, and the council can require non-compliant work to be altered or removed for up to 10 years after it was finished.
The more common problem comes when you sell. The buyer’s solicitor will ask for completion certificates. If you don’t have one, the options are a regularisation certificate, which may mean opening up the work, or an indemnity policy. An indemnity policy covers the legal risk, not the safety of the work, and most become void once the council has been contacted.
What’s changing: the Future Homes Standard
The Future Homes Standard was published on 24 March 2026 and comes into force for new homes in England on 24 March 2027. It requires solar panels on most new homes, low-carbon heating such as heat pumps, and tighter airtightness. Our guide to SIPs, timber frame and masonry explains what it means for how a new home is built.
How we help
We handle building control on every project we build. We make the application, book the inspections and hand you the completion certificate and installer certificates at the end. Find out more about our house extensions in Oxford, loft conversions, garage conversions and new build homes, or get in touch.
Frequently asked questions
Is it illegal to build without building regulations approval?
Yes. Breaking the building regulations is a criminal offence. Since the Building Safety Act changes in October 2023 it can bring an unlimited fine and up to two years in prison, and the council can make you alter or remove the work.
Does the 10-year rule apply to building regulations?
In a way. Since 1 October 2023 the council can serve a notice requiring non-compliant work to be altered or removed for up to 10 years after the work was finished. Before that the limit was 12 months.
Can I sell my house without a building regulations certificate?
You can, but the buyer’s solicitor will usually ask for completion certificates for any work that needed approval. Without one, you may need a regularisation certificate or an indemnity policy, and some buyers will walk away.
What is exempt from building regulations?
Small detached outbuildings under 15 m² with no sleeping accommodation, many porches and conservatories under 30 m² that are separated from the house by external doors, and like-for-like repairs and replacements. Electrical, gas and window work done by a registered installer is self-certified instead.
How long does building regulations approval take?
A full plans application should be decided within five weeks, or two months if you agree to an extension. With a building notice there is no approval stage: work can start two working days after the notice is given.
Who is responsible for building regulations, the builder or the homeowner?
Both. The person carrying out the work must comply, but the council can require the owner to put right work that doesn’t. Before work starts, check who is making the application and who will hand over the completion certificate.
How do I find out if work has building regulations approval?
Ask the council’s building control team. Oxford City Council and the district councils keep records of applications and completion certificates, and you can view many of them online. For self-certified work, ask for the installer’s certificate.
What are the key changes to building regulations in 2026?
The Future Homes Standard was published on 24 March 2026 and comes into force for new homes on 24 March 2027. It asks for solar panels, low-carbon heating and tighter airtightness.
Sources: Oxford City Council: building control; GOV.UK: Approved Document L 2026; Building Safety Act 2022, section 39. Checked October 2026.
