Planning & Regulations
Planning
permission
explained.
A plain-English guide to Permitted Development, planning applications, and Building Regulations for home extensions and loft conversions in the South West.
Single Storey Extensions
Most single storey extensions
don’t need planning.
Permitted Development
Most single storey rear extensions can be built under Permitted Development rights. For detached houses you can extend up to 8 metres from the rear wall; for semi-detached or terraced properties, 6 metres.
Prior Approval
Extensions between 4–8m (detached) or 3–6m (semi/terrace) require Prior Approval under the Neighbour Consultation Scheme. Simpler than full planning and usually granted within 8 weeks.
The Key Rules
When Full Planning Is Needed
Conservation areas, AONBs, listed buildings, and some Article 4 areas require a full planning application. Your matched Kura builder will confirm your position from the outset.
Two Storey Extensions
Two storey extensions
almost always need planning.
Two storey extensions extend beyond the plane of the existing roof and create new habitable space above ground floor. They almost always fall outside Permitted Development and require a full planning application.
Planning authorities assess two storey extensions on design quality, materials, relationship to the existing house, and impact on neighbouring properties – particularly overlooking and overshadowing. A good builder and, if needed, a planning consultant will guide you through this.
Typical timeline
Loft Conversions
Most loft conversions
don’t need full planning.
Permitted Development
Most loft conversions fall under Permitted Development – no planning application required. The total volume added must not exceed 50 cubic metres for detached and semi-detached houses, or 40 cubic metres for terraced properties.
When Planning Is Required
Conservation areas, listed buildings, and AONBs face tighter controls. Mansard conversions almost always require full planning. Hip-to-gable conversions on semi-detached properties sometimes do. Your builder will advise.
Building Regulations & Fire Safety
All loft conversions require Building Regulations approval, covering structural adequacy, fire safety, the new staircase, and insulation performance.
Fire safety is particularly important in loft conversions – Building Regulations require that the new loft room can be safely evacuated. This typically means fire doors on all habitable rooms leading off the staircase, mains-wired smoke alarms on every floor, and an escape window in the new room.
Your Kura builder manages all Building Regulations applications and the final Completion Certificate as part of the build. Nothing falls through the cracks.
Building Regulations
Always required.
Always managed.
Building Regulations approval is required for all extensions and loft conversions regardless of whether planning permission is needed. Where Permitted Development means no planning application is required, Building Regs still apply.
Your matched Kura builder submits all Building Regulations applications, manages the inspection process, and obtains the Completion Certificate at the end of the build. All of this is included in the Kura build process.
All structural work must meet the requirements of Approved Document A – foundations, beams, walls, and roof must be correctly designed and specified.
Approved Document L sets minimum thermal performance standards – your new extension or loft must meet or exceed these values.
Approved Document B covers means of escape, fire doors, smoke alarms, and structural fire resistance.
All new drainage, plumbing, and electrical work must meet Approved Documents H, G, and P respectively.
Start Your Project
Design your space.
We’ll handle the rest.
Use our configurator to design your extension or loft conversion. Your matched builder will manage all planning and Building Regulations as part of the build.
Start the Configurator