Planning permission and building regulations are not the same thing
Many homeowners think planning approval is the finish line. It's actually the halfway point.
| Planning permission | Building regulations | |
|---|---|---|
| What it controls | What your project looks like and how it affects neighbours and the street | How it's built: structure, fire safety, insulation, ventilation, drainage |
| Who decides | Your local council's planning department | Council building control, or a private Registered Building Control Approver |
| Is it always needed? | No, many projects are permitted development | Almost always, for extensions, loft conversions and structural changes |
| What we produce | Planning drawings and supporting documents | Technical drawings, specification and coordinated structural information |
Permitted development means you may not need planning permission. You'll still need building regulations approval.
Do I need building regulations approval?
Almost certainly, if you're:
- Building an extension
- Converting a loft or garage into a room people live in
- Removing or altering a load-bearing wall
- Adding or moving a bathroom or kitchen drainage
- Replacing a roof covering or windows (often through a competent person scheme)
- Carrying out notifiable electrical work
Usually not, for:
- Like-for-like repairs and redecorating
- Most small detached outbuildings under 15m² with no sleeping accommodation
- Ground-level conservatories and porches under 30m², with safety glazing, separated from the house by external-quality doors, and with no extension of the home's heating system
If you're not sure, ask us. It's a two-minute question on a free project call.
Choosing your approval route
There are three ways to get building regulations approval. We'll recommend the right one for your project.
Full Plans application (what we usually recommend)
Your drawings are checked before work starts. Building control must decide within 5 weeks, or 2 months if you agree to extend. Approval lasts 3 years. You know your design complies before a builder prices it, so there are no surprises on site.
Building Notice
No plans are checked in advance, and work can start 2 days after the notice is submitted. It's faster on paper but riskier: problems are found during construction, when they cost most to fix. A Building Notice can't be used if you're building over or near a public sewer, which is common with rear extensions.
Registered Building Control Approver (private)
Instead of the council, you can appoint a private approver registered with the Building Safety Regulator. You and the approver jointly give an Initial Notice to the council, which has 5 working days to reject it. Once it's accepted, and the approver has had 2 working days' notice, work can begin. Private approvers are often more flexible on site-visit timing.
What's in our building regulations package
- Technical plans, sections and elevations, detailed for construction
- Specification notes covering materials, insulation and build-ups
- Fire safety strategy, including protected escape routes for loft conversions
- Thermal details to meet current insulation standards
- Ventilation and extract layouts
- Drainage layout, with sewer proximity checked
- Coordinated structural calculations: beams, padstones and foundations (see Structural Engineering)
- Door and window schedule
- Submission to building control and responses to their queries
- Early warnings on party wall notices and build-over agreements, flagged before they delay your start date
The regulations, in plain English
The Building Regulations are explained through a set of official guides called Approved Documents. These are the ones that matter most for home extensions and loft conversions.
| Part | Covers | What it means for your project |
|---|---|---|
| A | Structure | New beams, lintels, joists and foundations must be designed to carry the loads. |
| B | Fire safety | Loft conversions need a protected stair route with fire doors, and mains-wired, interlinked smoke alarms on every level. |
| C | Damp and site preparation | Damp-proofing, weathertightness and ground conditions. |
| E | Sound | Sound insulation between rooms, and where walls are shared with neighbours. |
| F | Ventilation | Background vents and extract fans, especially in kitchens and bathrooms. |
| H | Drainage | Foul and rainwater drainage, including building near public sewers. |
| K | Falls and collisions | Stair dimensions, balustrades and safety glazing. |
| L | Energy efficiency | Insulation levels for walls, floors and roofs, and window performance. |
| M | Access | Mainly new homes: level access and WC provision. |
| P | Electrical safety | Notifiable electrical work by a registered electrician, or checked by building control. |
How it works and how long it takes
- Brief and review: we check your approved planning drawings and confirm the approval route. Days 1–2
- Technical design: drawings, specification and structural coordination. Usually within 2 weeks
- Submission: Full Plans decision within 5 weeks (or 2 months with your agreement), or an Initial Notice with a private approver (5 working days)
- Inspections: building control visits at key stages, such as foundations, drainage, structure and insulation
- Completion certificate: issued once the work is signed off. Keep it safe.
What does it cost?
Our fixed prices for building regulations drawings:
| Project | Price |
|---|---|
| Loft conversion | £525 |
| Single-storey extension | £600 |
| Creating new flats | £600 |
| Wraparound extension | £675 |
| Double-storey extension | £1,050 |
| New build | Priced per project |
Save with a bundle: book building regulations drawings with a measured survey and the second item is half price, from £750 for both. Structural engineering is priced for each project.
Drawings are available across England. Prices are final: there's no VAT to add.
Building control fees are paid separately to the council or private approver. As a guide, one London borough's 2026/27 schedule (Havering, including VAT):
| Project | Fee |
|---|---|
| Garage conversion, up to 30m² | £673 |
| Extension or loft conversion, up to 30m² | £859 |
| Extension or loft conversion, 30–60m² | £1,183 |
| Extension or loft conversion, 60–100m² | £1,406 |
Fees vary by council and project size; figures were correct in September 2026. We'll confirm the exact fee for your council.
Your responsibilities as a homeowner
Since October 2023, everyone involved in building work, homeowners included, has legal duties under the Building Regulations. The good news: as a domestic client, your duties normally pass to your builder (or principal contractor). They can pass to your designer instead if agreed in writing.
What that means in practice:
- Appoint people with the right skills and experience
- Where more than one contractor is involved, a principal designer and principal contractor must be appointed in writing
- Capital can act as your principal designer for the design stages
Why the completion certificate matters
- Selling your home: buyers' solicitors ask for it. Missing certificates cause delays, price reductions or failed sales.
- Enforcement: councils can require non-compliant work to be altered or removed up to 10 years after completion, and fines are unlimited.
- Insurance and mortgages: lenders and insurers may ask for proof that the work was approved.