TL;DR: Building regulations explained simply: they are the legal standards your finished work has to meet for safety, energy efficiency, and health, and they are separate from planning permission. Most extensions, loft conversions, and structural changes need building regs approval and sign-off from a building control body. The single most useful takeaway is to never start work without confirming which approvals apply, because unregistered work and a missing completion certificate cause the biggest problems at resale.
Almost every homeowner who plans a build hits the same wall of confusion early on. Two sets of rules sound similar, use overlapping jargon, and seem to apply at the same time: planning permission and building regulations. People assume the words are interchangeable, get one and forget the other, or treat the whole thing as a single tickbox a builder will handle invisibly. That misunderstanding is where avoidable cost and delay tend to start. This guide sets out, in plain terms, what building regulations are, how they differ from planning permission, what they cover, what needs approval, and who signs the work off, so you walk into your project knowing what is actually required of it. The rules described here are those for England.
Building regulations vs planning permission
These are two different systems run for two different reasons, and the building regulations vs planning permission distinction is the one worth getting straight before anything else.
Planning permission is about whether you are allowed to do the work at all. It deals with the external impact of what you are proposing: how a building looks, its size and height, its position on the plot, its effect on neighbours, on the street scene, and on the wider area. The decision sits with your local planning authority and is, in essence, a question of acceptability.
Building regulations are about how the work is built. They set minimum technical standards for the construction itself so the finished result is safe, healthy, and reasonably efficient to run. The decision is about compliance, not aesthetics, and it is assessed by a building control body rather than the planning department.
A useful way to hold the two apart: planning asks 'should this be built here, and may you build it?', while building regulations ask 'is it built properly and safely?'. The two are independent. A project can need both, just one, or, in limited cases, neither. Securing planning permission does not exempt you from building regulations, and many works that fall under permitted development, so needing no planning application, still have to comply with the regulations in full. Treating one as a substitute for the other is one of the most common and costly assumptions homeowners make.
What building regulations actually cover
The Building Regulations 2010 are the legal framework in England, and the detailed standards are set out across a series of Approved Documents, each labelled with a letter and dealing with a particular area of construction. You do not need to learn them, but it helps to know the spread of what is being assessed:
- Structure. That foundations, walls, beams, and load paths can safely carry the loads placed on them. Removing a load-bearing wall or forming a large opening falls squarely here.
- Fire safety. Escape routes, fire-resisting construction, alarms, and safe access. This becomes especially significant for loft conversions and any work that changes how people would get out in a fire.
- Insulation and energy efficiency. Thermal performance of walls, roofs, floors, glazing, and heating, so the building is reasonably efficient to run and meets current energy standards.
- Ventilation. Adequate fresh air and the control of condensation and moisture, particularly in kitchens, bathrooms, and newly insulated, airtight spaces.
- Drainage and waste. Foul and surface water are carried away correctly and connected appropriately.
- Moisture and weather resistance. Protection against damp rising, penetrating, or being trapped in the structure.
- Safety in use and accessibility. Stairs, guarding, glazing in critical locations, protection from falling, and reasonable access.
- Electrical and gas safety. Certain works must be carried out and certified to the relevant standards, often by a registered competent person.
The exact requirements that apply depend entirely on the nature of the project, and standards are updated over time, so the version in force when your work is carried out is what matters. Your building control body confirms which provisions apply to your specific job.
What work needs approval and what is exempt
As a general rule, building regulations approval is needed whenever you create a new building, extend or materially alter an existing one, or change how part of it is used in a way that affects the regulated standards. Common works that typically need approval include extensions, loft conversions, internal structural alterations such as removing load-bearing walls, converting a garage into a habitable room, underpinning, and new or altered drainage. Replacing certain controlled fittings, for example windows or a boiler, also falls under the regulations, though this is frequently handled through a registered installer's competent person scheme rather than a separate application.
Some minor works are exempt, and certain detached outbuildings or small structures may fall outside the requirements depending on their size, use, and proximity to boundaries. Exemptions are narrower and more conditional than people expect, and an apparently small job can still trigger requirements, for instance where it affects fire safety, structure, or energy performance. Because exemption depends on the precise details of your project, you should always confirm the position with your building control body before assuming any work is exempt rather than relying on a general rule of thumb.
Who signs it off: building control
Compliance is assessed and certified through building control. In England you have a choice of who carries out that role:
- Your local authority building control, the building control department run by your local council.
- A registered building control approver, an approved private-sector inspector authorised to carry out building control work.
Either route delivers the same outcome: an independent body checks that the work meets the regulations, inspects key stages on site, and issues a completion certificate once it is satisfied. That certificate is the document proving the work was signed off, and it is the piece of paper a future buyer's solicitor will ask to see. The building control body is not the same as the planning authority, even when both happen to sit within the same council, so applying to one does not register you with the other.
The two routes: full plans and building notice
When you do need approval through a local authority, there are broadly two procedural routes, and the right one depends on the size and complexity of the work.
- Full plans. You submit detailed drawings and specifications before work starts. The building control body reviews them against the regulations and can confirm compliance, or flag issues, on paper before anyone lifts a tool. This route gives the most certainty up front, which is why it suits larger, structural, or more complex projects, and it is often what lenders, warranty providers, and cautious homeowners prefer.
- Building notice. A lighter route for simpler work, where you notify the body that work is starting without submitting full plans for prior approval. Compliance is then judged largely through site inspection as the job proceeds. It can be quicker to begin, but it carries more risk, because a problem may only surface on site, after money has been spent, rather than being caught on the drawing board.
For most substantial residential work, the full plans route, or its equivalent through a private approver, gives you the strongest position, because compliance is agreed in principle before construction rather than discovered during it.
Do I need building regs for an extension?
If you are asking 'do I need building regs for an extension', the short answer is almost always yes. A typical single or double-storey extension involves new foundations, new structure, fresh insulation, often new drainage, and changes to fire safety and ventilation, every one of which is regulated. Extensions are among the clearest cases where building regulations apply in full, regardless of whether the extension also needs planning permission or falls under permitted development. The small handful of genuinely exempt additions, such as certain conservatories and porches below defined sizes and meeting specific conditions, are the exception rather than the rule, and even those conditions need checking against your particular situation. If your project is an extension, plan from the outset on the basis that building regulations apply.
Common pitfalls that cost money later
The expensive mistakes with building regulations rarely show up during the build. They surface years later, usually when you try to sell or remortgage.
- Unregistered work. Work done without the approval it needed has no record that it complies. Putting that right after the fact, sometimes through a regularisation application, is slower, more uncertain, and more expensive than doing it correctly the first time.
- No completion certificate. The job may have been built well, but without the certificate there is no proof it was signed off. Buyers' solicitors routinely ask for it, and its absence can stall or collapse a sale, or force the seller to buy indemnity insurance to paper over the gap.
- Problems at resale. Conveyancing searches and surveys frequently uncover historic work that was never registered. At that point the homeowner is negotiating from a weak position, often dropping the price or scrambling to retrofit paperwork under time pressure.
- Skipping inspections. Where required stages are not inspected, later trades can conceal the very work the building control body needed to see, leading to opening up finished surfaces to prove compliance.
- Assuming the trade handled it. 'The builder sorted it' is not evidence. If no one took clear ownership of the application, the inspections, and the final certificate, it is worth assuming it was missed until the paperwork proves otherwise.
The common thread is that none of these are construction faults. They are administrative gaps, and they are entirely avoidable when someone owns the compliance process from the start.
How a main contractor manages compliance end to end
This is the part homeowners most underestimate, and it is where a competent main contractor earns its place. Managing building control well is not a single submission, it is a thread that runs through the whole project: getting the right approvals in place before work starts, coordinating the technical detail with the design, booking and meeting the inspections at the correct stages, keeping the records straight, and securing the completion certificate at the end so the paperwork matches the building.
CJE Build manages building control and compliance so the homeowner does not have to. As Hertfordshire's trusted residential main contractor, working to one team, one standard, and no compromises, we run a single line of accountability from foundation to handover, which means one contact who is responsible for the regulations alongside the build itself. We have worked since 2010 across Hertfordshire and the Home Counties, including in conservation areas and within the curtilage of listed buildings, where the compliance picture is more demanding and the margin for error is smaller. We work closely with architects so that the design as drawn is the design that can actually be approved and built, rather than two documents that drift apart on site.
None of this removes your own responsibility as the homeowner to confirm what your project needs, and requirements vary from job to job, so your building control body remains the authority on your specific case. What it does mean is that the approvals, the inspections, and the certificate are owned, tracked, and closed out by people who do this every week, rather than left to chance. If you would rather not become an expert in the Building Regulations 2010 to extend your own home, that is the point of hiring a main contractor who handles it properly. You can get in touch to talk it through.
Frequently asked questions
What is the difference between planning permission and building regulations?
Planning permission decides whether you are allowed to carry out the work, based on its appearance, size, position, and impact on the surroundings, and it is decided by your local planning authority. Building regulations set the technical standards the construction itself must meet for safety, health, and energy efficiency, and they are checked by a building control body. They are separate systems, and a project can need one, both, or in limited cases neither, so meeting one does not satisfy the other.
Do I need building regulations approval for a loft conversion?
In almost all cases, yes. A loft conversion typically involves new structural support, changes to the staircase and floor, fire safety provisions, and insulation, all of which are regulated. It needs to be checked and signed off by a building control body, and you should plan from the outset on the basis that building regulations apply.
Do I need building regs for an extension?
For a typical extension, yes. Extensions usually involve new foundations, structure, insulation, drainage, and changes to fire safety and ventilation, all of which fall under the regulations. A small number of conservatories and porches below certain sizes can be exempt if they meet specific conditions, but those conditions need confirming for your particular project rather than assumed.
Who signs off building regulations work?
A building control body does. In England you can use your local authority's building control department or a registered private-sector building control approver. They inspect the relevant stages of the work and, once satisfied it meets the regulations, issue a completion certificate, which is your proof the work was signed off.
What happens if work was done without building regs?
Work carried out without the approval it required has no record of compliance, which tends to surface during a future sale or remortgage when a solicitor asks for the paperwork. You may be able to apply for retrospective approval, sometimes called regularisation, or arrange indemnity insurance, but both are more expensive and uncertain than getting it right at the time. It can also delay or reduce the value of a sale, so it is worth resolving rather than ignoring.
Is building regulations approval the same as a building warranty?
No. Building regulations approval is the legal sign-off that your work meets the required technical standards, evidenced by a completion certificate from your building control body. A structural warranty is a separate insurance-backed product that covers defects for a number of years and is provided by a warranty company, not the building control body. A project may have both, and they serve different purposes.
How long is a completion certificate valid for?
A completion certificate confirms the work was assessed as compliant at the time it was issued, and it does not expire, so it remains the document that evidences sign-off for that work. Keep it safe with your property records, because a future buyer's solicitor is likely to ask for it.