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Tell us your loft idea and we’ll confirm if it’s Permitted Development or needs planning permission — no jargon.
🎥 Watch: Planning Permission Loft Conversion (UK)
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Quick answer
Most loft conversions to a house are Permitted Development (PD) if you keep within the national limits: typical volume increase up to 40m³ (terraced) or 50m³ (semi/detached), no extension above the roof ridge, dormers set back from the eaves, and materials similar in appearance. Planning permission is needed if you exceed PD, face the highway with a front dormer, live in a conservation area/Article 4 zone, or in a flat/maisonette. For the bigger picture, see our pillar: Planning Permission — The Complete Guide.
When this applies (and when it doesn’t)
- Applies when: You’re converting the roof space of a house (not a flat) and the dormers/rooflights sit at the rear or side within PD volumes.
- Your dormer is set back from the eaves (commonly ~20cm), does not project beyond the plane of the existing roof slope that fronts the highway, and doesn’t exceed the roof’s highest point.
- Materials are similar in appearance; side windows are obscure-glazed and opening parts are high-level as required.
- Doesn’t apply when: You’re in a conservation area, a National Park, a World Heritage Site, or an area with an Article 4 Direction removing PD rights.
- You’re in a flat/maisonette (loft PD rights don’t apply), or your scheme exceeds PD volume/height rules or adds balconies/verandas.
Steps / Rules / Checklist
- Confirm PD status: Check conservation/Article 4 constraints and whether your home is a house (not a flat). Use our guide above and council map layers.
- Measure the roof volume: Ensure the additional volume is within ~40m³ (terrace) or ~50m³ (semi/detached), counting any previous roof enlargements.
- Design to PD rules: Rear/side dormers only, set back from eaves, no roof height increase, no front projection beyond roof slope facing the highway, side windows obscure-glazed.
- Decide on paperwork: If PD, submit an LDC (recommended). If not PD, prepare a Householder Planning Application with drawings and a short design statement.
- Sort Building Regulations: Loft conversions nearly always need Full Plans drawings/structural calcs and inspections (fire doors/escape route, floor joists, insulation/ventilation). Start here: Building Regulations — Complete Guide.
- Neighbour relations: If cutting into a party wall or raising steel on party structure, consider Party Wall procedures and agree access for scaffolding.
Costs & timeline (quick guide)
| Item | Typical range | Notes |
|---|---|---|
| Lawful Development Certificate (proposed) | ~half of a householder fee | Good proof for buyers/solicitors; target 8 weeks |
| Householder planning application | ~£250–£300 (England, guide) | If exceeding PD or front dormer; target 8 weeks |
| Drawings & structural calcs | Project-specific | Needed for Building Regs (joists, steels, fire, insulation) |
| Building Control | £400–£1,000+ (guide) | Full Plans (plan check + inspections) or Building Notice (simple jobs) |
Timescales vary by council workload and submission quality. We front-load details to cut queries and keep your build moving.
Local council quirks (Bucks · Milton Keynes · Guildford)
- Buckinghamshire: LDCs often run smoother with a scaled roof-volume diagram and an explicit eaves setback note on dormers. Some parishes are strict on front roof alterations.
- Milton Keynes: Expect emphasis on matching materials and side-window privacy (obscure glazing + high cill). Some officers ask for a simple overlooking note on the plan.
- Guildford: Central areas and conservation streets are more sensitive; Article 4 Directions remove PD in places — front dormers generally unacceptable without planning.
Not sure if your loft is PD?
We’ll check constraints, sketch a compliant dormer, and tell you whether to seek an LDC or full planning.
Mini-FAQs
Do I need planning permission for a loft conversion?
Most loft conversions to a house are PD within the 40/50m³ limits and other rules (no front dormer beyond the roof slope, ridge height unchanged). If not PD or in a protected area, you’ll need planning. See the overview: Planning Permission — The Complete Guide.What are the 40m³ / 50m³ rules?
They cap the additional roof space you can create: up to 40m³ for a terraced house and up to 50m³ for semi/detached, including any previous roof enlargements.Do I still need Building Regulations?
Yes. PD only affects planning. Loft conversions must meet Building Regulations (structure, fire safety, insulation, ventilation). Start here: Building Regulations — Complete Guide.Next steps
Check PD limits, sketch volume and eaves setbacks, then choose LDC or planning application as needed. We’ll package drawings, structural calcs and manage approvals so your loft passes first time. See the full guide: Planning Permission — The Complete Guide.
Ready to move your project forward?
Plans Made Easy can prepare compliant plans, manage submissions, and guide you from idea to approval.
Last updated: September 2025
