Key Takeaway
Millions of UK homeowners extend and improve their homes every year without needing a planning application. Understanding what's covered by Permitted Development rights — and what isn't — can save you time and money before a single drawing is produced.
Permitted Development Rights: The Homeowner's Freedom to Build
Every residential property in England — unless specifically restricted — comes with a set of built-in planning rights known as Permitted Development (PD). These allow you to carry out a range of alterations and extensions without submitting a planning application to your local council.
For Hampshire homeowners, understanding PD rights is practically valuable: a significant proportion of the extension projects Hampshire Build designs and delivers each year are either entirely within PD or only require a straightforward Lawful Development Certificate rather than a full planning application.
Single-Storey Rear Extensions
The most common extension type — and one of the most frequently misunderstood:
- Standard PD limit: Up to 4 metres beyond the rear wall of a detached house, or 3 metres for a semi-detached or terraced house
- Extended PD via Prior Approval: Up to 8 metres (detached) or 6 metres (semi/terraced) — but this requires a 42-day neighbour consultation process managed by the council. This is still not a planning application, but it's not entirely paperwork-free either
- Maximum height: 4 metres (single-storey) or 3 metres within 2 metres of a boundary
- Materials: Must be similar in appearance to the existing house
These limits apply to the principal rear elevation — if your house has a rear projection or bay, the calculation starts from the original rear wall, not any later addition.
Side Extensions
- Single storey only under PD (two-storey side extensions always need planning permission)
- Maximum height: 4 metres
- Width: no more than half the width of the original house
- Cannot extend forward of the principal elevation or side elevation facing a highway
- In conservation areas: side extensions visible from a highway require planning permission
Loft Conversions
- Volume allowance: Up to 40m³ for terraced houses, 50m³ for detached and semi-detached
- Must not extend beyond the plane of the existing roof slope on the principal or side elevation fronting a highway
- Rear dormers are permitted, but must be set back at least 20cm from the eaves
- No balconies or raised platforms in the extension — these always need planning permission
- Materials must be similar in appearance to the existing house
Garage Conversions
Converting an existing attached or integral garage to a habitable room does not normally require planning permission. The change of use from garage to habitable space is generally covered by PD, provided:
- The property isn't in an area where a planning condition specifically requires the garage to remain as parking (some new-build estates have this)
- You're not adding a new structural opening — if you're converting the existing space without external alterations, planning permission is very rarely needed
- The property is a house, not a flat or maisonette
Outbuildings and Garden Rooms
- Outbuildings — including home offices, studios, log stores and garden rooms — are permitted in the curtilage of a house without planning permission, provided they're single storey with a maximum eaves height of 2.5 metres and overall height of 4 metres (dual-pitch roof) or 3 metres (flat or mono-pitch)
- Must not be in front of the principal elevation
- In conservation areas: no outbuildings to the side or front without planning permission
- Cannot be used as a separate dwelling or self-contained living space
- Combined footprint of outbuildings must not exceed 50% of the original garden area
When PD Rights Are Removed or Restricted in Hampshire
PD rights are not universal. Properties in the following situations may have restricted or removed rights:
- Conservation areas: Common across Winchester, Romsey, Alton, Petersfield, Alresford and many Hampshire villages. Side extensions visible from a highway need planning permission; roof alterations face restrictions
- Article 4 Directions: Some parts of Southampton, Eastleigh and other urban areas have Article 4 Directions that remove specific PD rights. Check with your local planning authority before assuming PD applies
- South Downs National Park and New Forest: These are separate planning authorities with more restrictive policies. Extensions in either park are subject to enhanced scrutiny and are more likely to require full planning permission
- Listed buildings: PD rights do not apply to listed buildings or any property within a listed building's curtilage
- New-build properties: Some developers secure planning permission with conditions that remove or restrict PD rights. Check your planning permission documents
- Flats and maisonettes: PD rights don't apply
The Lawful Development Certificate: Why You Should Get One
Even when your extension clearly falls within PD, we strongly recommend obtaining a Lawful Development Certificate (LDC) from the council. This costs £258 and takes approximately 8 weeks. It provides:
- Official written confirmation that your extension is lawful under PD
- Protection when you come to sell — your solicitor will ask about planning compliance, and an LDC resolves this cleanly
- Peace of mind that a future change to PD rules or your area's designation cannot retrospectively affect your position
Proceeding without an LDC is legal, but it's a risk we don't recommend taking.
Still Need Building Regulations
It's important to be clear: Permitted Development covers planning only. It does not exempt you from Building Regulations. Any extension — regardless of the planning route — must comply with Building Regulations and requires a full technical drawing package for Building Control. Hampshire Build prepares both planning drawings and Building Regulations packages as part of our fixed-fee service.
Book a complimentary consultation to discuss your extension — we'll confirm your planning position, advise on PD or LDC, and provide a fixed fee for the design work.
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