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GPDO 2015 England Permitted Development rules · statutory fees effective 1 April 2026

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Extensions & Lofts Schedule 2, Part 1 · Class A · 3m/4m

Single-Storey Rear Extension Rules: How Far Can You Build Without Planning?

Under GPDO Part 1 Class A you can extend a semi-detached or terraced house by 3m and a detached house by 4m without any application. The Larger Home Extension scheme doubles that to 6m / 8m through a £249 Prior Approval with a 42-day neighbour consultation. Set your dimensions below to see which route applies.

If PD
£0
Application
£548
Decision
8 wks

Step 1 · Your project

Single-Storey Rear checker

House type
3.0m

Measured externally from the rear wall of the original house – include any earlier extension.

Is the extension within 2m of a boundary?
2.7m
3.6m
Conservation area, National Park, National Landscape, Broads or WHS?
Will buildings cover more than 50% of the garden?

Rules reflect the GPDO 2015 (England) for houses. Flats, maisonettes, listed buildings and Article 4 areas have restricted rights. Disclaimer.

Step 2 · Live statutory assessment

Permitted Development – Class A

Class A · 3m/4m

At 3.0m deep with 2.7m eaves, your extension is standard Class A Permitted Development. Building Regulations approval is still required.

  • Depth 3.0m is within the 3m standard Class A limit.
  • Eaves height 2.7m complies with the boundary rules.
  • Overall height 3.6m is within the 4.0m limit.
SIDE ELEVATION – REAR PROJECTION & EAVES
ORIGINAL HOUSE EAVES 2.7m PRIOR APPROVAL 6m STANDARD PD 3m PROJECTION 3.0m

England fees & timings (from 1 April 2026)

Council application fee

£0

Standard Class A right

Lawful Development Certificate

£274

Strongly advised before building

Decision time

0 weeks

LDC takes ~8 weeks if chosen

Applying online via the Planning Portal adds a £91 service charge (inc. VAT).

Builder & neighbour spec sheet

Export these exact limits and your answers to share with your contractor.

At a glance

Single-Storey Rear: the statutory limits in England

  • Standard PD: max 3m beyond the original rear wall for semi-detached and terraced houses, 4m for detached.
  • Larger Home Extension: up to 6m (semi/terrace) or 8m (detached) via Prior Approval – £249 fee, 42-day decision.
  • Max 4m overall height, and 3m eaves if within 2m of any boundary; eaves never higher than the existing house.
  • Extensions and outbuildings must not cover more than 50% of the garden around the original house.
  • Exterior materials must be of similar appearance to the existing house (conservatories excepted).
  • ‘Original’ means the house as at 1 July 1948, or as first built if later – previous owners’ extensions count.

Statutory reference

Legislation summary & 2026 fee table

England statutory planning fees effective 1 April 2026. Wales, Scotland and Northern Ireland operate different regimes.

GPDO legislation and fee summary for Single-Storey Rear Extensions
Primary legislation Town and Country Planning (General Permitted Development) (England) Order 2015 (SI 2015/596), as amended
GPDO Schedule / Part Schedule 2, Part 1
Class Class A – enlargement, improvement or other alteration of a dwellinghouse
Exact reference GPDO 2015 Sch.2 Pt.1 Class A, A.1(e)–(k), A.1(g) & A.4 (Larger Home Extension)
Standard application fee £548 – Householder planning application
Lawful Development Certificate (proposed) £274 – optional proof the works are lawful
Prior Approval (Larger Home Extension) £249 – 42-day neighbour consultation
Planning Portal service charge £91 (inc. VAT) if submitted online
Council determination period 8 weeks (Prior Approval: 42 days)
Key exclusions Larger Home Extension not available on Article 2(3) land or SSSIs. No Class A rights for flats or maisonettes.

Avoid enforcement

The 3 most common homeowner traps

Trap #1

Previous owners used up your allowance

Your 3m or 4m is measured from the original rear wall – the house as it stood on 1 July 1948 or when first built. If a previous owner added a 2m kitchen extension in the 1990s, a semi-detached house has only 1m of standard PD left. Check old planning records and building control completion certificates.

Trap #2

Measuring from inside, or from the wrong wall

Projection is measured externally, from the outside face of the original rear wall to the outside face of the new rear wall. Measuring internally, or from an existing conservatory, typically understates depth by 300–600mm – enough to push a ‘3m’ extension over the limit.

Trap #3

Starting before Prior Approval is granted

The Larger Home Extension route requires the council’s decision (or the 42-day deemed approval) before work starts, and you must build exactly what was notified and tell the council when it is complete. Starting early removes PD protection and exposes you to enforcement.

Separate legal regimes

Building Regulations vs planning permission

Every habitable extension needs Building Regulations approval – via Full Plans or a Building Notice – whether or not planning permission is required:

Structure (Part A)
Opening up the rear wall needs calculated steel beams and padstones; foundations must suit the soil, trees and nearby drains.
Insulation (Part L)
New elements must meet Approved Document L limiting U-values – typically 0.18 W/m²K walls and floors, 0.15 roofs, 1.4 windows.
Drainage (Part H)
Building over or within 3m of a public sewer needs a build-over agreement with the water company before work starts.
Fire & electrics (Parts B and P)
Smoke detection must be extended to new rooms, and new circuits are notifiable electrical work.

Rear extensions on semi-detached and terraced houses almost always trigger the Party Wall etc. Act 1996: Section 1 (new wall on the boundary line – one month’s notice), Section 2 (cutting into the party wall for flashings or beams – two months) and Section 6 (foundations within 3m of a neighbour’s building and deeper than theirs – one month).

FAQs

Single-Storey Rear: frequently asked questions

How far can I extend a semi-detached house without planning permission?

3m beyond the original rear wall as standard Permitted Development, or up to 6m using the Larger Home Extension Prior Approval scheme (£249 fee). Eaves within 2m of the boundary must not exceed 3m and overall height must stay under 4m.

How does the 42-day Prior Approval process work?

You submit a description, plan and dimensions with the £249 fee. The council notifies adjoining neighbours, who have 21 days to object. It then decides on amenity impact alone. If you have no decision within 42 days, the extension is deemed approved.

Do I need planning permission for a side return or wrap-around extension?

Single-storey side extensions are PD up to 4m high and no wider than half the original house. A wrap-around (side plus rear) is assessed as one extension and usually breaches the side-extension width rule, so it normally needs a householder application (£548).

Can I use the Larger Home Extension scheme in a conservation area?

No. Prior Approval for 6m/8m extensions is not available on Article 2(3) land (conservation areas, National Parks, National Landscapes, the Broads, World Heritage Sites) or on SSSIs. You can still use the standard 3m/4m rights unless an Article 4 Direction removes them.

Sources: The Town and Country Planning (General Permitted Development) (England) Order 2015 and amendments (legislation.gov.uk); MHCLG ‘Permitted development rights for householders: technical guidance’; the Town and Country Planning (Fees for Applications…) (England) Regulations 2012 as amended; Building Regulations 2010 Approved Documents; Party Wall etc. Act 1996. Last reviewed 15 October 2026. See our editorial standards and disclaimer.

Related planning checkers

Class A · 3m/7m

Two-Storey Rear Extensions

Max 3m deep, 7m to rear boundary, matching roof pitch

Open checker
Class A · <30m²

Conservatories & Orangeries

Same footprint limits as extensions, 30m² Building Regs exemption

Open checker
Class B · 40/50m³

Loft Conversions & Dormers

40m³ terraced / 50m³ semi & detached, rear dormers only

Open checker