Planning Permission vs Building Control: What's the Difference?
One of the most common questions we hear from homeowners is: "Do I need planning permission for this?" — closely followed by "What about Building Control?"
They're two completely separate processes, and understanding the difference can save you time, money, and legal headaches. Here's a clear guide from a structural engineer's perspective.
Planning Permission — Do You Need It?
Planning permission is about what you can build and where. It's controlled by your local council's planning department.
You Usually Need Planning Permission For:
- Two-storey extensions
- Side extensions in some areas
- Loft conversions with large dormers (front dormers especially)
- Changes in a Conservation Area
- Building closer than 2 metres to a boundary (above certain heights)
- Converting a house into flats
You Usually Don't Need Planning Permission For:
- Single-storey rear extensions (under certain size limits)
- Most loft conversions (under Permitted Development)
- Internal alterations (removing walls, chimney breasts)
- Like-for-like replacements (new roof in same style)
These rules fall under Permitted Development rights. But there are conditions and limits — and some properties have had these rights removed. Always check with your local council before assuming.
Building Control — You Almost Always Need It
Building Control (also called Building Regulations) is about how the work is done. It ensures the building is structurally safe, energy efficient, and meets fire and accessibility standards.
You Need Building Control Approval For:
- Any structural work — loft conversions, extensions, wall removal, chimney breast removal
- New foundations or underpinning
- Electrical work (rewiring, new circuits)
- Plumbing changes (new bathrooms, moving drainage)
- Window and door replacements
- Changes to fire escape routes
This Is Where a Structural Engineer Comes In
Building Control requires structural calculations and often structural drawings to prove the work is safe. That's what we produce.
For example, if you're converting your loft:
- Your architect draws the layout (where the stairs go, room sizes)
- Your structural engineer designs the steel beams, floor joists, and staircase opening so the structure is safe
- Building Control checks our calculations and issues approval
Without structural engineer involvement, Building Control won't approve the work.
What Happens If You Don't Get Building Control?
This is serious. If you've had structural work done without Building Control sign-off:
- You can't prove the work is safe
- It will flag on a property search when you try to sell
- Your buyer's solicitor will likely demand a regularisation certificate
- Your home insurance may not cover structural issues
The fix? A retrospective Building Control application. At SBS, we produce the retrospective structural calculations and reports your council needs to issue a regularisation certificate. Learn more about our retrospective applications service.
The Process: Planning, Building Control, and Your Structural Engineer
Here's the typical sequence for a home project:
- Design your project — with an architect or designer (layout, appearance)
- Check planning — does it need planning permission, or is it Permitted Development?
- Structural engineering — we design the steelwork, foundations, and structural details
- Submit to Building Control — we prepare the structural calculations and drawings
- Building Control approval — they review and approve (usually 2–4 weeks)
- Construction begins — your builder works from our drawings
- Building Control inspections — they visit during and after construction
- Completion certificate — Building Control signs off the finished work
How Long Does It Take?
| Stage | Typical Timeline | |---|---| | Planning application (if needed) | 8–12 weeks | | Structural calculations & drawings | 5–7 working days (SBS standard) | | Building Control review | 2–4 weeks | | Express structural service | 48 hours (SBS express) |
At SBS, we prepare your structural calculations within one week as standard. Our express service delivers in 48 hours for urgent projects.
Common Scenarios
"I want to remove a load-bearing wall"
- Planning permission: No (internal alteration)
- Building Control: Yes — you need a structural engineer to design the supporting steel beam
- Steel beam calculations →
"I want a loft conversion"
- Planning permission: Usually no (Permitted Development) unless it's a front dormer or you're in a Conservation Area
- Building Control: Yes — structural engineer needed for beams, floor joists, staircase opening
- Loft conversion structural engineering →
"I want a rear extension"
- Planning permission: Usually no for single-storey under size limits
- Building Control: Yes — foundations, steelwork, and structural details required
- Extension structural engineering →
"I want to remove a chimney breast"
- Planning permission: No
- Building Control: Yes — gallows brackets or steel beam needed to support the stack above
- Chimney breast removal →
Get Expert Advice
Not sure whether your project needs planning permission, Building Control, or both? We're happy to advise.
At SBS Structural and Architectural Design, we provide free consultations for homeowners across London, Essex and Kent.
- Phone: +44 7401 650 600
- Email: sbs.structures@gmail.com
- Office: 61 Cranbrook Road, Ilford, IG1 4PG
We'll tell you exactly what you need — no jargon, no hard sell.
