Quick Answer
Building Regulations approval is required for most significant building work — including extensions, loft conversions, garage conversions, structural alterations and major plumbing or electrical work. You apply either via Full Plans (submitted before work starts) or a Building Notice (submitted just before work starts). Fees typically range from £200 to £1,000 for residential projects.
Planning permission often gets all the attention, but Building Regulations approval is equally important — and unlike planning permission, it applies to most significant building work regardless of whether the project is Permitted Development. In 2026, failing to obtain Building Regs approval can cause serious problems when you come to sell your home. This guide explains exactly what Building Regs cover, how to apply, and what you need to do to get a Completion Certificate.
In this guide
What Building Regulations Cover
Building Regulations set minimum standards for the design and construction of buildings in England. They are separate from planning permission and cover:
- Structure (Part A): Ensuring buildings are structurally stable
- Fire safety (Part B): Means of escape, fire resistance, alarm systems
- Site preparation and resistance to contaminants and moisture (Part C)
- Toxic substances (Part D)
- Sound insulation (Part E)
- Ventilation (Part F): Adequate fresh air, extraction in kitchens and bathrooms
- Hygiene (Part G): Sanitary facilities, hot water safety, water efficiency
- Drainage and waste disposal (Part H)
- Combustion appliances and fuel storage (Part J)
- Protection from falling (Part K)
- Conservation of fuel and power (Part L): Insulation and energy efficiency — one of the most demanding areas in 2026
- Access and facilities for disabled people (Part M)
- Glazing (Part N): Safety glazing in critical locations
- Electrical safety in dwellings (Part P): Notifiable electrical work
- Security (Part Q): Doors and windows in new dwellings
The regulations don't tell you how to build — they tell you the standards you must achieve. Your builder and designer must specify construction methods that meet these standards.
What Work Needs Building Regulations Approval
The following work almost always requires Building Regulations approval:
- Any extension to a house (single-storey or multi-storey)
- Loft conversions
- Garage conversions to habitable space
- Basement conversions
- Structural alterations (removing load-bearing walls, inserting beams)
- New bathrooms or WCs (drainage work)
- Re-roofing (if more than 25% of the roof area)
- Installing new windows and doors (in certain circumstances)
- Certain electrical work (Part P notifiable work)
- Installation of a new boiler or heating system
- Solar PV panels (some installations)
- Underpinning foundations
Work that generally does NOT need Building Regs approval includes: small porches (under certain thresholds), conservatories (subject to conditions), most repairs and maintenance, and simple like-for-like replacements.
For context on what requires planning permission separately, see our guide on planning permission for extensions and our Permitted Development guide.
Full Plans vs Building Notice — Which Should You Choose?
| Feature | Full Plans | Building Notice |
|---|---|---|
| Drawings required upfront? | Yes — detailed drawings required | No |
| When approved? | Before work starts (5–8 weeks) | Approval confirmed during build |
| When can work start? | After plan approval | 2 days after notice |
| Certainty before building? | High — problems found before work | Lower — issues found on site |
| Cost if problems found? | Lower — can redesign plans | Higher — may need to undo work |
| Completion Certificate issued? | Yes | Yes (if all inspections pass) |
| Best for? | New extensions, loft conversions, complex work | Simple or time-sensitive works |
| Can be used for? | All works | Not for new commercial buildings or flats |
For most homeowners undertaking extensions or loft conversions, the Full Plans route is recommended. Although it takes longer upfront, you get certainty before any money is spent on construction that your design is compliant. A Building Notice is better suited to simpler works where the compliance is less in doubt.
How to Apply for Building Regulations Approval
You have two options for who assesses your application:
- Local Authority Building Control (LABC): Apply to your local council's Building Control department. This is the traditional route. Fees are set by each local authority but are regulated. The service is publicly accountable.
- Approved Inspector (now called Registered Building Control Approver): A private firm registered with the RICS or CICAIR. You'll need to agree fees (often competitive with LABC) and they typically offer a more responsive service. Following the Building Safety Act 2022, Approved Inspectors have been rebadged as Registered Building Control Approvers (RBCAs).
The application typically requires:
- A completed application form
- Drawings (for Full Plans route): plans, elevations, sections and construction details
- Structural calculations (from a structural engineer) where relevant
- Energy calculations (SAP assessment for new buildings; condensed calc for extensions)
- The application fee
Building Regulations Application Fees
Fees vary by local authority and by the scale of the work. Here are typical 2026 fee ranges for residential projects in England:
| Project Type | Full Plans Fee | Building Notice Fee |
|---|---|---|
| Single-storey extension (under 10m²) | £200–£400 | £250–£450 |
| Single-storey extension (10–40m²) | £300–£600 | £400–£700 |
| Two-storey extension | £400–£800 | £500–£900 |
| Loft conversion | £350–£700 | £450–£800 |
| Garage conversion | £200–£500 | £250–£550 |
| Basement conversion | £500–£1,000 | N/A (Full Plans recommended) |
| New dwelling | £750–£2,000+ | N/A |
Site Inspections During the Build
Building Control inspectors will visit the site at key stages to check the work is compliant. You or your builder must notify the inspector at each stage. Typical inspection points include:
- Commencement: Before any work starts (or within 2 days of starting for a Building Notice)
- Excavations: Before concrete is poured for foundations
- Foundations: Before oversite concrete is laid
- Damp proof course: Before floor screed is laid
- Structural steelwork: Before it's hidden behind walls or plasterboard
- Roof structure: Before the roof covering is applied
- Insulation: Before it's hidden by plasterboard
- Drains: Before backfilling
- Completion: Final inspection before issuing the Completion Certificate
Make sure your builder knows to call for inspections at each stage — do not let them cover up work before the inspector has seen it. This is a very common source of problems on residential projects.
The Completion Certificate
Once all inspection stages are passed and the final inspection is complete, Building Control issues a Completion Certificate (or a Final Certificate for LABC, or a Final Notice for an Approved Inspector). This document is the proof that the work was completed in accordance with Building Regulations.
A Completion Certificate is essential:
- When selling your home — solicitors will ask for it
- When re-mortgaging
- For insurance purposes
- To demonstrate compliance if the council ever investigates the works
If work was carried out without Building Regs approval, it is possible to retrospectively regularise it through a Regularisation Certificate — but this is more expensive, more stressful and the inspector may require opening up of walls or floors to check hidden work.
For help hiring the right builder for your project, see our guide on how to hire a builder in the UK. And if your project is near a shared boundary, don't forget the Party Wall Act obligations.
Frequently Asked Questions
Do I need Building Regulations approval for a conservatory?+
Not usually, if the conservatory is: at ground level; under 30m²; separated from the house by an external-quality door and wall; has an independent heating system; has more than half its roof and walls in translucent material; and is not used as a bedroom. If any of these conditions are not met, Building Regs will apply.
What is the difference between planning permission and Building Regulations?+
Planning permission is about whether you're allowed to build at all — it controls the use of land and the visual impact of development. Building Regulations are about how you build — they ensure the work is safe, structurally sound, and energy efficient. You may need one, both, or neither, depending on the project.
Can I start work before getting Full Plans approval?+
No — if you use the Full Plans route, you must wait for plan approval before starting. If you use the Building Notice route, you can start after 2 days. However, using a Building Notice means less certainty about compliance upfront, which can be costly if problems are found on site.
What happens if I don't get Building Regulations approval?+
The local authority can issue an enforcement notice requiring you to pull down or remove unauthorised work within a specified time. There's no time limit for enforcement of Building Regs non-compliance (unlike planning enforcement, which has a 4-year limit for dwellings). It will also cause problems when selling, as solicitors will identify missing approvals.
Who is responsible for making sure Building Regulations are complied with — me or my builder?+
Legally, you as the building owner are responsible for ensuring Building Regulations approval is obtained and that the work complies. In practice, builders usually notify Building Control and arrange inspections as part of their service — but you should check this is happening. Don't assume your builder is handling it without confirming.
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