Summary

Permitted development (PD) rights allow homeowners to carry out certain building works without making a planning application. These rights are defined in the Town and Country Planning (General Permitted Development) (England) Order 2015 (GPDO) and its amendments. Understanding them correctly is essential both for builders (advising clients) and homeowners (avoiding enforcement action).

The most common permitted development question is about rear extensions. The government expanded PD rights for single-storey rear extensions in 2013, increasing the limits from 3m (attached houses) and 4m (detached houses) to 6m and 8m respectively under a Prior Approval notification system. These expanded limits were made permanent in 2019.

Permitted development rights can be removed or restricted by planning conditions, article 4 directions (covering conservation areas, national parks, and AONB), or by covenants. A Certificate of Lawful Development (CLD) from the local planning authority provides formal confirmation that works are permitted development — this is recommended before starting significant works and is required by some mortgage lenders.

Key Facts

  • Permitted development legislation — Town and Country Planning (General Permitted Development) (England) Order 2015 (GPDO) and amendments
  • Single-storey rear extension (standard PD) — 4m deep (detached); 3m deep (semi/terrace); no higher than eaves; no more than 4m overall height at any point
  • Single-storey rear extension (Prior Approval) — up to 8m deep (detached); up to 6m deep (semi/terrace); notification required; neighbours consulted
  • Two-storey rear extension — 3m deep maximum; must not be closer than 7m to the rear boundary; no balconies
  • Side extension maximum width — half the width of the original house (the "original" house = as built or as of 1948)
  • Height limits — single-storey extension: no higher than the eaves of the main dwelling; two-storey: no higher than the main ridge
  • Roof extensions (dormer windows) — permitted development on rear slopes only; maximum roof extension volume 40m³ (50m³ for detached); not on designated land
  • Conservation areas — PD rights for rear extensions are restricted; some works require planning permission; cladding the exterior of a house also requires permission
  • Listed buildings — NO permitted development rights; ALL extensions and alterations require Listed Building Consent
  • Flats and maisonettes — NO permitted development rights for extensions; planning permission always required
  • Volume limit — any extension must not increase the volume of the original house by more than 50% cumulatively (applies to the original building)
  • Certificate of Lawful Development (CLD) — optional but strongly recommended formal confirmation from LPA; costs £100–£250; valid indefinitely
  • Wales and Scotland — different PD regulations apply; this article covers England only

Quick Reference Table

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Extension Type Standard PD Limit Prior Approval Limit Notes
Single-storey rear (detached) Up to 4m depth 4–8m depth (notification required) Height: max 4m; no eaves higher than existing
Single-storey rear (semi/terrace) Up to 3m depth 3–6m depth (notification required) Same height rules
Two-storey rear extension Up to 3m depth N/A — planning required beyond 3m Min. 7m from rear boundary
Single-storey side extension Half house width N/A Not on designated land
Wrap-around extension Complex — get CLD — L-shaped; side + rear; each element assessed
Porch Up to 3m² floor area, under 3m high N/A Cannot exceed 2m in height if within 2m of highway
Outbuilding/garden building Max 50% curtilage; max 2.5m at eaves if within 2m of boundary N/A Not used as main accommodation
Loft conversion (rear dormer) 40m³ volume addition (50m³ detached) N/A Not on front elevation; not in conservation area
Garage conversion Generally PD N/A Internal conversion; no external change
Designation Effect on PD Rights
Conservation Area Roof extensions on front restricted; cladding restrictions; rear extensions still permitted (but check specific area)
Area of Outstanding Natural Beauty (AONB) Rear extensions limited to 3m (semi/terrace) or 4m (detached) — standard limits only; no Prior Approval route
National Park Same as AONB
Article 4 Direction Local authority removes some or all PD rights; check with LPA
Listed Building ALL works require Listed Building Consent; no PD rights

Detailed Guidance

The Prior Approval Process for Larger Extensions

Extensions between the standard PD limit and the extended PD limit (e.g., 4–8m deep for detached houses) require Prior Approval notification — a simplified process, not a full planning application.

Process:

  1. Submit an application to the LPA with plans, description of the works, and the addresses of immediately adjoining properties
  2. The LPA notifies the immediate neighbours (not a general public consultation — just the adjoining properties)
  3. Neighbours have 21 days to respond
  4. If no valid objection, the LPA issues Prior Approval Not Required notification (or Prior Approval Granted)
  5. If objections are received on impact to amenity/light, the LPA assesses and may impose conditions or refuse
  6. Works must commence within 3 years of the Prior Approval

Fee: £120 (as of 2026) [verify current fee].

Key point: Prior Approval is NOT planning permission. The LPA can only consider the impact on neighbouring amenity — not design, appearance, or character of the area. This is why Prior Approval is generally more straightforward than a full planning application.

What Counts as the "Original" House

PD rights are measured against the "original" dwelling — the building as it stood when first built, or as at 1 July 1948 (whichever is later). This means:

  • If the house was extended by a previous owner, those extensions count toward the cumulative PD limits
  • If you buy a house that already has a rear extension, the depth of that existing extension counts against your PD allowance
  • Check Land Registry title deeds and original planning consents to understand what was built and when

Example: A semi-detached house built with a 1m outrigger at the rear. The previous owner added a 2m extension. The original house depth was 8m; with the 1m outrigger it was 9m. The previous owner extended to 11m (2m addition). You want to extend further. Your PD allowance is 3m from the original rear wall of 9m (not counting the outrigger as original, as it was added later) — so you can extend to 12m. But 11m already exists, so only 1m additional PD is available.

This calculation often requires reviewing the planning history of the property on the LPA's planning portal.

Certificate of Lawful Development

A CLD is a formal confirmation from the LPA that a specific work is lawful (either because it doesn't need permission, or because it has planning permission). Two types:

  • Prospective CLD (s192): for proposed works; confirms that the proposed development is PD
  • Existing use CLD (s191): for completed works; confirms that completed development was lawful

Why get a CLD:

  • Mortgage lenders and buyers require it when selling a property where work has been done
  • It provides long-term legal certainty — if the rules change, the CLD remains valid
  • It protects against enforcement action
  • Some lenders won't lend on properties where extensions have been made without formal confirmation

Cost: £100–£250 in England (LPA fee; professional fees additional if using a planning consultant or architect).

When You Cannot Use Permitted Development

Several situations remove PD rights entirely or significantly:

Designated land (conservation areas, AONB, national parks, World Heritage Sites):

  • Cladding the exterior: requires planning permission in conservation areas
  • Front extensions and porches: restricted or prohibited in conservation areas
  • Side extensions: restricted in conservation areas
  • Rear extensions in standard PD limits still generally apply (with some variations by designation)

Article 4 Directions: Local planning authorities can remove PD rights for specific areas using an Article 4 Direction. These are common in historic town centres and conservation areas. Check the LPA's website or contact the planning department before committing to any significant work.

Previous conditions: Planning conditions on the original permission for the house, or on a previous extension, can remove PD rights. For example, "No further extensions shall be erected without planning permission" is a common condition that removes all PD rights for extensions. Review any planning permissions on the property.

New build properties: Many new build estates have Article 4 Directions or planning conditions that restrict extensions and alterations to preserve the character of the development. Buyers are often unaware of this.

Planning Applications: When They're Needed

Full planning applications are required for works that exceed PD rights. Key points for building over the PD thresholds:

  • Application fee — £206 for householder applications (extensions, loft conversions) in England as of 2026 [verify]
  • Decision timescale — 8 weeks for most householder applications; 13 weeks for major applications
  • Supporting information — site location plan (1:1250), block plan (1:500), existing and proposed floor plans and elevations; sometimes design and access statement
  • Approval rate — approximately 80–85% of householder applications are approved nationally; local rates vary
  • Pre-application advice — many LPAs offer pre-application advice (fee-charging); valuable for complex or borderline proposals

Frequently Asked Questions

Does a garage conversion need planning permission?

A straightforward internal garage conversion (no external changes, no change to the roof or external walls beyond filling the garage door opening with a window or door) is generally permitted development. However, if the property is in an area where off-street parking is in short supply, the LPA may resist the loss of the garage as parking provision through a planning condition. Check before proceeding. A CLD is strongly recommended.

My neighbour wants to extend right to our boundary — can they?

A single-storey rear extension can be built right up to the boundary with the adjoining land as long as it complies with the PD limits. They don't need your permission under planning law. However, the Party Wall Act 1996 applies if the extension involves work within 3m of your land or if it involves excavation near your foundations — see party wall for the Party Wall Act process. You can register an objection to Prior Approval for larger extensions (4–8m range) on grounds of impact on your amenity or light.

What if I've already built something without checking?

If work was completed more than 4 years ago (for operational development like extensions), the LPA generally cannot take enforcement action — this is the 4-year rule under Section 171B of the Town and Country Planning Act 1990. For a change of use, the period is 10 years. In both cases, a CLD for existing use (s191) can be obtained to formalise this.

If the work was recent and you're not sure it complies: get a CLD immediately. If the LPA decides it doesn't comply, enforcement action can include requiring demolition. Many issues can be regularised retroactively with a retrospective planning application.

Is a planning consultant needed for a straightforward householder application?

For a simple rear extension application: usually not, if you can draw basic plans. Many homeowners submit their own householder applications through the Planning Portal (the national online application system). For anything borderline (conservation area, large extension, unusual design), a planning consultant or architect adds value by improving the quality of the application and managing the LPA relationship.

Regulations & Standards

  • Town and Country Planning (General Permitted Development) (England) Order 2015 (SI 2015/596) — primary legislation defining permitted development rights; Schedule 2 Part 1 covers dwellinghouses

  • The Town and Country Planning (Development Management Procedure) (England) Order 2015 — procedural requirements for planning applications

  • Planning Policy Guidance (PPG): Prior Approval — government guidance on the Prior Approval process

  • The Planning Portal — national online planning application system (planningportal.co.uk)

  • Planning Portal: Permitted Development — interactive PD guide for householders

  • MHCLG: Permitted Development Rights for Householders — technical guidance document; essential reference

  • Planning Portal: Apply for Planning Permission — online application system

  • party wall — Party Wall Act obligations for work near boundaries

  • foundations — foundation requirements for extensions

  • structural steel — structural elements in extensions

  • building control — building control requirements alongside planning