For small builders and main contractors (England)
Last reviewed: March 2026
Your clients mix these up all the time. Some builders do too on the edges. Here's the clean split so you can stop arguing and start pointing at something sensible.
What each one actually is
Building Regulations = how you build it so it's safe and performs properly - structure, fire, damp, drains, insulation, access, electrics, etc. Checked by Building Control.
Planning Permission = whether you're allowed to build it there and in that shape - size, look, impact on neighbours/street/land use. Checked by the Planning department / Planning Inspectorate.
Two separate systems, with separate applications, fees, officers and decisions. You often need both.
At a glance - which jobs need what?
(England, typical domestic scenarios. Local policies can tighten things.)
| Job | Building Regs? | Planning Permission? | Notes |
|---|---|---|---|
| Rear extension within Permitted Development (PD) | Yes | Usually no (if it meets PD rules) | BC still care about structure, fire, drains, insulation, access etc.; PD only covers planning. |
| Rear extension beyond PD limits | Yes | Yes | Needs full planning AND Building Regs. |
| Loft conversion - rooflights only (no big dormer, within PD) | Yes | Usually no | Floor, structure, fire, insulation, stairs all need Regs; planning only if you break PD (e.g. front roof, big volume, conservation). |
| Loft conversion - rear dormer (within PD envelope) | Yes | Usually no | Same as above; once it breaks PD (size, height, side dormer, conservation) you're into planning too. |
| New build house | Yes | Yes | Full planning + full Building Regs; nothing grey here. |
| New-build block of flats | Yes | Yes | Same, but more complex on both sides. |
| HMO conversion (house → HMO) | Yes | Usually yes or at least prior approval / Article 4 | Change of use (planning) plus full fire/sound/amenity Regs; licensing on top. |
| Other change of use (office/barn → resi) | Yes (or change-of-use Regs) | Yes or prior approval | Planning handles land-use; Regs handle turning it into safe dwellings. |
| Window replacement like-for-like | Yes (via FENSA/CERTASS or BC) | Usually no | Planning can bite in conservation/Article 4; Regs ALWAYS bite on performance, safety, ventilation. |
| New log burner / multi-fuel stove | Yes (Part J) | Usually no | Planning only if you're in a special area / altering external appearance; Regs via HETAS or BC regardless. |
| Garden office / outbuilding (small, no sleeping, within PD) | Often yes (if insulated/heated) | Usually no (if within PD limits) | PD handles planning; once it's a proper room with services/insulation, Regs kick in even if planning doesn't. |
| Garden office used as bedroom/annexe | Yes | Very likely yes | Sleeping use pretty much guarantees both systems will be interested. |
| Solar panels on roof (standard domestic) | Yes (structure/fire/electrics) | Usually no (PD) | PD covers planning for most roofs; Regs still apply for loading, fixing, electrics, sometimes fire. |
| Satellite dish on house | No Regs (normally) | Sometimes planning | Commonly PD, but front/roofline/conservation can trigger planning; Building Regs rarely involved beyond basic fixing. |
| New driveway / hardstanding | Regs: usually no (except over sewers) | Planning/SUDS sometimes | Surfacing over X m² in front garden needs SUDS-compliant surface or planning; build-over near sewers needs water company & Part H. |
| Internal non-loadbearing alterations (stud only) | Sometimes (if you hit fire/sound) | Usually no | If you don't affect structure, escape routes or separating walls, BC may not need to see it. |
| Internal load-bearing wall removal | Yes | Usually no | Structure, fire, sound, access still matter; planning generally doesn't care what you do inside. |
| Chimney breast removal | Yes | Usually no | Building Regs for structure/fire; planning only if you alter external stack in a sensitive area. |
| Boundary wall/fence (typical heights) | No Regs (normally) | Planning sometimes | Over certain heights or along highways needs planning; Regs only if it's effectively a retaining/structural wall with risk. |
Classic mistakes you can head off early
"We've got planning so we're fine"
No you're not. Planning only says "we're happy with the size and look". You still need Building Regs and BC sign-off for the build itself.
"It's Permitted Development so I don't need anything"
PD only means you don't need a planning application. It says nothing about Building Regs - most PD-type works (lofts, extensions, outbuildings with services) do still need Regs.
"It's only internal"
Internal structural changes, fire escape changes, new bathrooms/kitchens, rewires, boilers - all can be pure Building Regs jobs with no planning at all.
"We'll sort Regs later if anyone asks"
That's called regularisation; it's always more expensive and more disruptive than doing it properly from day one.
What happens if you have one but not the other
You have planning but no Building Regs
- The job might look lovely and be totally unsafe or non-compliant.
- No completion cert; pain at sale/mortgage; possible enforcement/regularisation later.
You have Building Regs but no planning (and you needed planning)
- BC can't legalise a breach of planning.
- Planning enforcement can demand alteration or demolition, regardless of how well built it is.
You have neither
- Works risk action from both sides and are a hand grenade waiting to go off when the owner sells or someone complains.
Lawful Development Certificates (LDCs) - when they're worth it
A Lawful Development Certificate is planning's way of saying:
"This use or development is lawful, either because it's PD or because it's been there long enough without action."
Useful when:
- You're doing a job under Permitted Development but the client wants belt-and-braces proof.
- You've got an old extension/loft/use and want to nail down that planning can't come after it now.
It doesn't replace Building Regs or conjure up compliance. It just locks in the planning side so future planners and surveyors can't argue about whether it should have had planning.
If you remember nothing else, remember this
Planning = "Can we build this here, like this?"
Building Regs = "If we build it, will it be safe and up to standard?"
You usually need both boxes ticked. One without the other is where the grief starts.
This page is a general guide for small builders and main contractors working on dwellings in England. It doesn't cover every local policy or special site. Always check the latest Planning Portal guidance, local planning rules, Approved Documents, your drawings/spec and Building Control before you start cutting or pouring. SiteKiln does not provide legal, financial or tax advice. All content is for general information purposes only. Always seek professional advice for your specific situation.
Common questions
What is permitted development?
Permitted Development Rights (PDR) are pre-approved planning rules that let you build certain works without permission. They cover certain extensions, outbuildings, and alterations under the Town and Country Planning Order 2015. Limits vary by property type and location. Get a Lawful Development Certificate to confirm in writing.
Planning Permission Checker tool.
What is a Lawful Development Certificate?
A formal document from your council confirming a building or use is lawful and doesn't need planning permission. It costs around £120 for proposed work, takes 8 weeks, and protects you from future enforcement. Buyers' solicitors regularly demand one when the property is sold.
Planning Permission Checker tool.
Know someone who needs this?
Working in Wales? The building rules are different. See our Working in Wales guides.
Working in Scotland? Building standards work differently. See our Working in Scotland guides.
Working in Northern Ireland? The system uses Technical Booklets. See our Working in Northern Ireland guides.
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