Permitted Development for House Extensions: The Complete Checklist

Before relying on Permitted Development, confirm that your PD rights have not been removed or limited:

**Check 1 — Is the property a house (not a flat)?** PD Class A (extensions) applies only to 'dwellinghouses' — houses and bungalows. Flats (self-contained units in purpose-built or converted buildings) have very limited PD rights — extensions are not permitted.

• **Check 2 — Is the property in a Conservation Area?**
• In a Conservation Area, certain PD rights are restricted:
• •Side extensions of any size require planning permission
• •Cladding the exterior of the house with a different material requires planning permission
• •Roof extensions and outbuildings visible from the highway require planning permission
• Note: rear extensions in a Conservation Area still benefit from Class A PD rights, subject to all normal size limits.

**Check 3 — Is the property a Listed Building?** Listed buildings have no PD rights for extensions — any extension or alteration requires Listed Building Consent (and usually planning permission).

**Check 4 — Has the property been previously extended?** Permitted Development limits apply to the total extensions built since 1 July 1948 (the date of the first GDPO). If a previous extension was built under PD, the volume used by that extension counts toward the current PD limits. You must check what was built originally and what was built since 1948.

**Check 5 — Is there an Article 4 Direction?** An Article 4 Direction removes specific PD rights in a defined area. London boroughs use Article 4 Directions widely — not just in conservation areas, but in some Article 4 areas covering the whole borough (for specific classes). Check with your LPA before proceeding.

**Check 6 — Has a Condition been attached to a previous planning permission removing PD rights?** Planning conditions can remove PD rights — for example, a permission for a previous extension may have included a condition 'Notwithstanding the provisions of the GPDO, no further extensions shall be built...' Check the planning history for the property at the LPA's online planning portal.

**Check 7 — Is the property in the curtilage of a Listed Building?** If the property is within the curtilage (grounds) of a listed building — even if the property itself is not listed — permitted development may be removed.

The main PD class for house extensions is Class A (Part 1, Schedule 2 of the GPDO). The key limits are:

• **Single-storey rear extensions**:
• •Maximum depth: 8 metres from the original rear wall (for a detached house); 6 metres from the original rear wall (for a semi-detached or terrace)
• •Maximum height: 4 metres at the highest point; 3 metres if within 2 metres of a boundary
• •Maximum eaves height: 3 metres if within 2 metres of a boundary
• •Must not extend beyond the side elevation of the original dwelling (i.e., must not widen the house at the rear elevation if it projects beyond the line of the side wall)

**Neighbour consultation for larger single-storey extensions (LHE scheme)**: For extensions between 4–8m (detached) or 3–6m (attached), a neighbour consultation scheme applies — formally the 'Prior Approval' or 'Householder Prior Approval' route. You submit a form to the LPA; they notify neighbours; if no objection, Prior Approval is confirmed. This is not the same as planning permission — it is a lighter-touch process. The extension must meet all the other Class A conditions.

• **Two-storey rear extensions**:
• •Maximum depth: 3 metres from the original rear wall (both detached and attached)
• •Must not be within 7 metres of any boundary opposite the rear wall
• •Maximum height: must not exceed the height of the original dwelling

• **Side extensions (single-storey)**:
• •Maximum width: 50% of the width of the original dwelling
• •Maximum height: same as single-storey rear (4m at highest point; 3m within 2m of boundary)
• •Must not be in a Conservation Area or World Heritage Site (side extensions in these areas require full planning permission)
• •Not permitted at the principal elevation side (e.g., if the side elevation is visible from the highway in a corner plot)

• **Two-storey side extensions**:
• •Generally NOT permitted under PD in any circumstances — two-storey side extensions always require full planning permission

• **Wraparound extensions** (rear + side):
• •The rear portion follows rear extension rules; the side portion follows side extension rules. The combined must satisfy both sets of limits simultaneously. A common issue: the side element of a wraparound must not exceed 50% of the original house width, even if the rear element is within the PD limits.

Outbuildings in the curtilage of a dwellinghouse are covered by Class E (Part 1, Schedule 2, GPDO):

• **What Class E covers**:
• •Sheds, garages, summerhouses, garden rooms, greenhouses, and any outbuilding in the garden
• •Swimming pools within the curtilage
• •Hard surfaces (drives, patios) — also under Class F

• **Class E key limits**:
• •Must not be forward of the principal elevation (i.e., must be behind the front of the house, not in the front garden)
• •Maximum height: 2.5 metres if within 2 metres of a boundary; 4 metres for a dual-pitch roof; 3 metres for any other roof form
• •Total footprint of all outbuildings (combined) must not exceed 50% of the total area of the curtilage (excluding the footprint of the original house)
• •Must not be used as a separate dwelling (must remain ancillary to the main dwelling)
• •For a listed building curtilage: Class E does not apply — full planning permission and Listed Building Consent required

• **Outbuildings in Conservation Areas**:
• •Outbuildings visible from a highway or public open space in a Conservation Area require planning permission — even if they would otherwise be PD under Class E

**The 'no separate dwelling' rule**: This is the most important planning law consideration for garden annexes and outbuildings. If a garden outbuilding or garden room is used as a self-contained independent dwelling (i.e., the occupant lives there independently, not merely as an ancillary space supporting the main dwelling), this constitutes a material change of use and requires planning permission regardless of the building's size. Ancillary use (a home office, a granny annex where the occupant uses the main house for day-to-day living, a guest bedroom) is generally acceptable under Class E. Independent use (the occupant has no connection to the main house and lives there as a separate household) is not.

**Prior Approval (Class Q, R, S, T and others)**: For certain changes of use (agricultural buildings to dwellings, commercial to residential), a Prior Approval application rather than full planning permission may be available. These are complex and property-specific — specialist planning advice is required.

**Lawful Development Certificate (LDC)**: If you are proceeding under PD but want formal confirmation that your development is lawful, apply for a Lawful Development Certificate. This is a formal decision from the LPA confirming that the development described is lawful. It is not required — but it provides legal certainty and removes ambiguity at the point of sale or mortgage. Cost: LPA fee is 50% of the equivalent planning fee; typical LPA fee £103–£462 depending on the LPA.