Building regulations and planning permission are two entirely separate systems — and confusing them is one of the most expensive mistakes a homeowner can make. Planning permission controls whether you can build something at all. Building regulations control how it must be built, to ensure it is structurally sound, fire-safe, energy-efficient, and healthy to live in. You can sometimes have one without the other, and you can easily need both.
This guide explains which works require building regulations approval, which are exempt, how to obtain approval, and what happens if you carry out notifiable works without it.
Building Regulations vs Planning Permission
Planning permission is granted (or refused) by your local planning authority. It focuses on land use, appearance, and impact on the surrounding area.
Building regulations approval is issued by your local authority's building control department, or by an approved inspector. It focuses entirely on how the work is constructed — the technical standards it must meet.
A loft conversion, for example, almost always requires both: planning permission (unless permitted development applies) and building regulations approval (because structural, fire safety, and insulation standards must be met). A new porch extension under 30m² may be exempt from planning permission but still require building regulations approval. Always check both systems independently.
For a detailed breakdown of what planning permission requires, see our guide to home extension permitted development vs planning.
Works Exempt from Building Regulations: Schedule 2
Schedule 2 of the Building Regulations 2010 lists classes of work that are exempt from the regulations. Key exemptions include:
Small detached buildings — A detached single-storey building not used as a dwelling, with a floor area under 15m², is exempt. Between 15–30m², it is also exempt provided it contains no sleeping accommodation and is located at least 1m from any boundary (or is constructed from non-combustible materials).
Conservatories under 30m² — Exempt if: at ground level, separated from the main dwelling by external-quality walls, doors, or windows, and the glazing complies with Part N (safety glazing). If you remove the thermal separation (opening up the conservatory fully into the house), it ceases to be exempt and the whole extended area becomes subject to energy efficiency requirements.
Porches — Exempt if: at ground level, under 30m² in floor area, with no new heating installation.
Some garden buildings and outbuildings — Exempt from building regulations if under 15m² with no sleeping accommodation (see detached buildings above).
Certain agricultural buildings — Exempt where not frequently visited.
Notifiable Works: What You Must Seek Approval For
The following categories of work are notifiable under building regulations. Carrying them out without approval is a criminal offence and creates significant problems when you come to sell.
| Work type | Why it is notifiable |
|---|---|
| Extensions (any size) | Structural elements, energy performance, fire safety |
| Loft conversions | Floor/roof structure, fire escape, insulation, stair gradient |
| Structural alterations (removing walls) | Load-bearing assessment, beam specification |
| New electrical installation (in England) | Part P — full or consumer unit rewires are notifiable |
| New bathrooms (drainage, certain locations) | Part H drainage, Part P electrics |
| Boiler replacement or new heating system | Part L energy efficiency, Part J combustion appliances |
| Underpinning | Major structural work |
| Reroofing over 25% of the total roof area | Structural loading, insulation |
| Change of use (e.g. garage to habitable room) | Energy, ventilation, structural floor, fire safety |
| New window installations (unless FENSA registered) | Part L energy performance |
This is not an exhaustive list. If you are uncertain whether a specific project requires approval, consult your local building control department — many offer free pre-application advice.
For loft conversions in detail, see our loft conversion costs and planning guide.
The Two Approval Routes
Full Plans Application
You submit detailed drawings and specifications to building control before work begins. An inspector checks the plans, approves them (with or without conditions), and then carries out site inspections at key stages during the build.
This route is recommended for larger or more complex projects because it identifies problems before they are built rather than after.
- Fee: Varies by local authority and project value; typically £200–£800 for a single-storey extension
- Plan check: Usually 5 weeks (can be extended to 2 months by agreement)
- Inspections: Foundation, damp proof course, structural elements, insulation, and final completion
Building Notice
You notify building control that you are about to begin work, without submitting full drawings in advance. An inspector visits during the build and advises on compliance.
This route is faster and simpler for straightforward projects, but carries more risk — if the inspector requires changes, they may have to be made to already-completed work.
- Building Notices cannot be used for commercial premises or where a fire safety certificate is required
- There is no approved plan document, which can create problems when selling — see completion certificates below
Competent Person Schemes: Self-Certification
Registered tradespeople under government-approved competent person schemes can self-certify their own work without you needing to notify building control separately. The scheme operator notifies the local authority on your behalf and you receive a certificate.
| Scheme | Covers |
|---|---|
| Gas Safe Register | Gas boiler installation and gas pipework |
| NICEIC / NAPIT | Electrical installation (Part P) — see our complete guide to rewiring a house in the UK for costs, process, and what a full rewire involves |
| FENSA / CERTASS | Window and door replacements |
| HETAS | Solid fuel and biomass heating appliances |
| OFTEC | Oil-fired boilers and appliances |
Always ask any tradesperson working under a competent person scheme to provide you with their scheme registration certificate and to confirm that the installation has been registered. You should receive a completion certificate from the scheme operator within a few weeks of the work being done.
Completion Certificates and Why They Matter
A completion certificate (or final certificate) is issued when building control confirms that the notifiable works have been inspected and comply with building regulations. It is not a certificate of quality — it does not mean no problems will ever arise. But it is your legal evidence that the works were signed off.
Completion certificates matter for three reasons:
- Conveyancing: Solicitors acting for a buyer or mortgage lender will ask to see the completion certificate for any notifiable works carried out since the property was built. If you cannot produce one, the transaction may stall.
- Mortgage lenders: Some lenders will not lend on properties where notifiable works have been carried out without building regulations approval.
- Insurance: Certain works — particularly structural — may not be covered by your buildings insurance if they were not subject to building regulations approval.
Always keep your completion certificates safe. If you lose them, you can request copies from your local authority's building control department (fees typically apply).
Retrospective Regularisation
If notifiable works have already been carried out without building regulations approval — by you or by a previous owner — you can apply for a regularisation certificate. This is only available for works carried out after 11 November 1985.
Building control will inspect the works (which may require opening up sections of wall, ceiling, or floor to expose structural and services elements), assess compliance, and require remedial works if necessary before issuing the certificate.
- Cost: Typically 1.5× the normal application fee, plus any remedial works
- Estimated range: £200–£600 for the application alone, more if works need remediation
If regularisation is not possible — for example, because works have been hidden and an inspection would cause disproportionate disruption — some solicitors arrange indemnity insurance as an alternative. This protects the buyer (and their lender) against the financial consequences of the local authority taking enforcement action. Indemnity policies typically cost £200–£500 for a single project.
Consequences of Carrying Out Work Without Approval
The local authority has the power to require you to pull down or alter any work carried out without building regulations approval. This power expires 12 months from the date of completion for most works (though not for building works erected in contravention of regulations). After 12 months, the authority may take action in the magistrates' court instead.
The practical consequences are:
- Enforcement notice from building control requiring alterations
- Criminal prosecution (rare but possible)
- Problems on sale — lenders and buyers' solicitors will spot the gap in documentation
- Difficulty obtaining buildings insurance for the altered areas
The permitted development rights picture — and how it intersects with building regulations — is covered in our guide to permitted development rights UK 2025.
10 Common DIY Projects: Needs Approval or Exempt?
| Project | Building regs required? | Notes |
|---|---|---|
| Garden shed under 15m² | Exempt | No sleeping accommodation, not a dwelling |
| Garden shed 15–30m², over 1m from boundary | Exempt | Non-combustible materials or 1m+ from boundary |
| New conservatory under 30m² with thermal separation | Exempt | Must retain thermal separation from main house |
| New porch under 30m² | Exempt | Ground floor, no heating |
| Single-storey rear extension | Required | Full Plans or Building Notice |
| Loft conversion | Required | Full Plans strongly recommended |
| Removing a load-bearing wall | Required | Structural engineer's calculation typically needed |
| Replacing all windows (non-FENSA contractor) | Required | FENSA contractor can self-certify |
| Installing a new gas boiler (Gas Safe engineer) | Self-certified | Gas Safe engineer notifies automatically |
| Re-roofing over 25% of roof area | Required | Under 25% may be exempt as repair |
What to Do Next
- Identify your project type. Is it on the exempt list or the notifiable list?
- Contact your local building control department for free pre-application guidance if unsure.
- Choose your route: Full Plans for complex projects, Building Notice for straightforward smaller works.
- Use competent person scheme contractors where available — they self-certify and save you a separate notification step.
- Keep all completion certificates. File them with your property deeds.
- If buying a property, ask your solicitor to check the building regulations history for any notifiable works carried out since 1985.
- If there is a gap, commission a regularisation application or discuss indemnity insurance with your solicitor before exchange.
For a worked example of Building Regs in a specific project context — covering Part P electrics, Gas Safe for gas work, and Part H drainage — see our kitchen renovation planning guide UK. When appointing a contractor for notifiable works, see our how to find a reliable builder UK guide for the vetting hierarchy and contract essentials.
For specific project guides with Building Regulations deep-dives: Garage Conversion Living Space UK (Parts A/B/C/F/L/P and Part O overheating), Knocking Down Internal Walls UK (Part A structural), Planning a Loft Bedroom UK (Parts A/B/K/L), and Heat Pump Installation UK (Parts J/L and MCS).
- Barn Conversion: Planning Permission and Building Regulations UK — how Building Regulations apply to agricultural to residential change of use, Parts A–Q requirements, and Part L U-value targets
- Listed Building Consent: What Needs It, How to Apply, and Enforcement — Building Regulations requirements that apply alongside listed building consent for any alteration work
- Building Regs Completion Certificate Missing UK: Your Three Options — when a project was completed without a final inspection, this guide explains regularisation, indemnity insurance, and how to resolve it before a sale
- HMO Fire Safety: Landlord Obligations in England — how Part B of Building Regulations interacts with the Regulatory Reform (Fire Safety) Order 2005 for HMO conversions and fit-outs
- Planning Enforcement: What Happens If You Build Without Permission in the UK — if works went ahead without the necessary consents, this guide covers enforcement notices, immunity periods, retrospective applications, and Lawful Development Certificates
- Garden Room vs Extension: Planning Permission and Building Regs Compared — how the building regulations exemption for garden rooms under 30m² works in practice, and why extensions always need approval regardless of size
- Solar Panels and Planning Permission: What UK Homeowners Need to Know — which solar installations are permitted development under Class A Part 14 GPDO, and the building regulations notification requirements for solar PV systems