Building Regulations vs Planning Permission — What's the Difference? (UK 2026)

Building Regulations and planning permission are two separate UK regulatory systems. They're easy to confuse — both involve council approval for construction work. But they cover different things, apply in different circumstances, and you might need one, both, or neither for any given project. Here's the clear breakdown.

Planning permission — what it covers

Planning permission is concerned with land use and visual impact on the surrounding area. It's a system administered by your local council's planning department under the Town and Country Planning Act 1990. The questions planning asks:

• Should this kind of building/use exist in this location?
• Will the appearance of the new build harm the area?
• Will it affect neighbours' amenity (light, overlooking, noise)?
• Is it appropriate for the conservation area / listed building status?
• Does it comply with the local development plan?

Building Regulations — what they cover

Building Regulations are concerned with technical standards of construction. They're administered by Building Control (either your council's Building Control team OR a private Approved Inspector). The questions Building Regs ask:

• Is the structural design adequate?
• Is the fire safety adequate?
• Are the energy efficiency standards met?
• Is the building accessible to all users?
• Is the ventilation adequate?
• Is the drainage adequate?
• Are the materials and workmanship to a safe standard?

The key difference — visual/locational vs technical/safety

Planning asks 'should this exist here, in this form?'. Building Regs asks 'is it built safely and to standard?'.

An extension can have planning permission but fail Building Regs (e.g., approved design but built with inadequate foundations). Or it can comply with Building Regs but lack planning permission (e.g., structurally sound but built without permission). Both situations are problems requiring different fixes.

When you need planning permission

• Most extensions to a dwelling (unless within permitted development limits)
• Most loft conversions involving roof changes (Velux only is usually OK)
• Building outbuildings beyond permitted development limits (typically over 30sqm or close to boundaries)
• Change of use (e.g., shop to residence, residence to HMO)
• Demolition of any building in a conservation area
• Most external alterations in conservation areas (windows, doors, paint colour, render)
• Any work to a listed building (separate Listed Building Consent also required)
• Erecting substantial external signage
• Subdividing a house into flats
• Most commercial change of use

When you DON'T need planning permission

• Most internal alterations (no impact on external appearance)
• Interior decoration and refurbishment
• Replacing kitchens, bathrooms, internal doors
• Most extensions within Permitted Development rights
• Like-for-like maintenance and repair
• Most repointing, re-roofing in matching materials
• Solar panels on rear roofs (front roof in conservation areas usually does need planning)

When you need Building Regulations approval

• Any structural work (removing load-bearing walls, installing RSJs, underpinning)
• Any extension (any size, regardless of permitted development status)
• Any loft conversion
• New bathrooms (if drainage changes)
• New kitchens (if drainage or electrical changes are significant)
• Heating system replacement
• Replacing windows or doors (FENSA / CERTASS / ASSURE typically handle compliance automatically when fitted by registered installers)
• Installing a new bathroom in a previously non-bathroom space (loft, basement)
• Replacing the roof covering on more than 50% of the roof
• Electrical work on certain notifiable circuits (Part P)
• Most loft insulation upgrades over a certain depth
• Solar panel installation
• Underpinning

When you DON'T need Building Regulations

• Pure decoration (paint, wallpaper)
• Replacing internal doors that don't affect fire safety
• Replacing flooring
• Replacing kitchen cabinets and worktops (without changing drainage or electrical)
• Garden landscaping that doesn't involve excavation near foundations
• Garden sheds and outbuildings under 30sqm with no plumbing/electrics or specific exemption conditions

How Building Regs approval works

Routes to approval

• Local Authority Building Control — your council's department. Straightforward, well-established, typically £600-1,500 for a residential extension.
• Private Approved Inspector — independent BR specialists. Often more responsive than council, slightly higher fees (£800-2,000 for a residential extension). Examples: BBS, MD Insurance, Premier Guarantee.

Application types

• Building Notice — simpler, used for small straightforward projects (small extension, kitchen renovation). Submit description; work can start in 48 hours.
• Full Plans — detailed drawings submitted in advance; approval (or conditions) issued in 5-15 working days. Required for larger or complex projects. Provides certainty before starting.

Inspection stages

Building Control inspects at key stages — typical for an extension:

• Foundations excavated (before pouring concrete)
• Foundations poured (before backfilling)
• Damp-proof course installed
• Drains laid (before backfilling)
• Roof structure complete
• Insulation in place
• First-fix complete
• Final completion

Builder books inspections at the right times. Building Control issues a Completion Certificate at the end — essential document. Required when selling the property.

When both planning and Building Regs apply (most extensions)

A typical London single-storey rear extension under permitted development:

• Permitted development — no planning permission required (assuming size limits met)
• Building Regulations — required, must be submitted and complied with

A typical loft conversion needing planning permission:

• Planning permission — required (conservation area or beyond PD limits)
• Building Regulations — also required
• These are submitted separately and processed independently

What happens if you ignore each

Building without planning permission

Council can issue an Enforcement Notice requiring you to remove the unauthorised work (typically within 4-12 weeks). After 4 years for development that doesn't change use (extensions, alterations), or 10 years for change of use, the work can become 'immune' from enforcement under planning law — but this doesn't help if you're trying to sell during those years.

Building without Building Regulations approval

Council can issue a Building Regs Enforcement Notice requiring you to expose the work for inspection (e.g., remove plaster, lift floors) and bring it up to standard. Costs typically £5-25k of remedial work. Council can prosecute — fines up to unlimited (typically £5-15k). Affects future property sales — buyers' solicitors will require Regularisation Certificate or Building Regs Compliance Certificate.

What the certificates mean for selling

When you sell a property, the buyer's solicitor will ask for documentation:

• Planning permission decision notice — for any work requiring it
• Building Regulations Completion Certificate — for any work requiring BR approval
• Lawful Development Certificate — formal confirmation that PD work was lawful (recommended even though not required)
• FENSA / CERTASS certificates — for replacement windows and doors
• Electrical Installation Certificate — for electrical work
• Gas Safe certificate — for boiler installations

Missing certificates can derail a sale or force you to take out indemnity insurance (typically £150-400 per missing certificate).

Frequently asked questions

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