Permitted Development Rights UK: Extensions, Outbuildings and Porches Explained

Permitted Development (PD) rights allow homeowners to carry out certain building works without applying for full planning permission. They are granted by the Town and Country Planning (General Permitted Development) Order 2015 (GPDO), as amended, and apply to dwelling houses in England. Wales, Scotland, and Northern Ireland have their own equivalents with different limits.

Understanding PD rights can save you £200–£500 in planning fees, months of waiting, and considerable uncertainty. Understanding their limits can save you from building something unlawfully.

What Permitted Development Is — and Isn't

PD rights are not permission to build anything without consequence. They are a form of pre-granted planning consent for works that Parliament has decided are unlikely to cause planning harm if carried out within defined limits. You still need to comply with:

Building Regulations — almost all structural work, electrical work, drainage, and insulation still requires Building Regs approval regardless of PD status. See our Building Regulations approval UK guide for what's notifiable.
Party Wall Act 1996 — if the work affects a shared wall or is within 3–6 metres of a neighbour's foundations. See our Party Wall Agreement UK guide.
Restrictive covenants — private legal restrictions on your title may prohibit extensions even where PD applies.
Article 4 Directions — local planning authority directions that remove some or all PD rights in designated areas (conservation areas, certain streets and wards).

Rear Single-Storey Extensions

This is the most commonly used PD right. Under Class A of the GPDO:

Detached houses: Up to 8 metres beyond the rear wall of the original house.
Semi-detached and terraced houses: Up to 6 metres beyond the rear wall.
Maximum height: 4 metres (or 3 metres if within 2 metres of a boundary).
Eaves height: Must not exceed 3 metres within 2 metres of a boundary.

Prior Approval is required for extensions beyond 4 metres (detached) or 3 metres (semi/terrace) up to the maximum 8m/6m limits. This is the Neighbour Consultation Scheme — the council notifies adjoining owners, who have 21 days to object. The council's powers are then limited to considering only highways safety, flood risk, and site contamination. If no decision is issued within 42 days, the extension may proceed.

Extensions within the lower limits (up to 4m/3m) do not require Prior Approval — but a Lawful Development Certificate (LDC) is still advisable.

House Type	No Prior Approval Needed	Prior Approval Required
Detached	Up to 4m	4–8m
Semi-detached / terraced	Up to 3m	3–6m

For a full breakdown of extension costs once you know what you can build, see our house extension costs UK guide.

Two-Storey Rear Extensions

Two-storey rear extensions under PD must:

Be no closer than 3 metres to the rear boundary.
Not exceed the eaves height of the existing house.
Comply with the 45-degree rule — the extension must not project beyond a 45-degree line drawn from the nearest point of the nearest neighbour's window.
The upper floor must not create a balcony or raised platform overlooking neighbours.

Two-storey PD extensions are significantly more constrained than single-storey. Many fall outside PD limits and require a full planning application.

Side Extensions

Side extensions under PD:

Single-storey only — two-storey side extensions require planning permission.
Must not exceed half the width of the original house.
Must not be closer to the highway than the existing house (or within 20 metres of a highway if the building sits closer to the highway than 20m).

Side extensions are frequently outside PD if the property is on a corner plot, near a designated highway, or in an Article 4 area.

Outbuildings

Outbuildings (sheds, summerhouses, home offices, garden rooms, garages) fall under Class E of the GPDO.

Rule	Limit
Maximum coverage	50% of the total original garden area
Eaves height (within 2m of boundary)	2.5 metres
Ridge height (dual-pitch roof)	4 metres
Ridge height (flat/mono-pitch)	3 metres
Location	Must not be forward of the principal elevation
Designated land	Closer than 20m to the house on designated land — only if total floor area ≤10m²

Outbuildings used as ancillary accommodation (a separate living space with sleeping, cooking, and bathroom facilities) do not fall within Class E and require full planning permission.

Porches

A front porch can be added under PD provided:

The total ground floor area does not exceed 3 square metres.
The height does not exceed 3 metres.
It is at least 2 metres from any boundary with a highway.

No Prior Approval is needed for porches within these limits, but check for conservation area status first.

Loft Extensions

PD rights for loft conversions are granted under Class B — but the rules and roof volume limits make this a complex area. See our detailed guide: Loft Conversion UK: Planning Permission, Building Regs and Costs.

Garage Conversions

Converting a garage to habitable use is generally permitted development (no planning permission needed) provided you are not in a designated area and the building retains its existing footprint. Building Regulations approval is still required. For the full process, costs, and structural requirements, see our garage conversion UK guide.

Article 4 Directions and Conservation Areas

An Article 4 Direction removes specified PD rights in a defined area. They are most commonly used:

In conservation areas — to protect the character of streetscapes by requiring planning permission for changes to windows, doors, cladding, and roof materials.
In certain residential streets where the local authority has determined that PD rights would harm the area's amenity.

If your property is in a conservation area, assume you do not have full PD rights until you have verified the position with the local planning authority. Victorian and Edwardian properties are particularly likely to be in Article 4 areas — see our Victorian and Edwardian house renovation guide.

The Lawful Development Certificate

Even where work is clearly within PD limits, a Lawful Development Certificate (LDC) is strongly recommended. An LDC is a formal decision from the council confirming that your proposed (or completed) works are lawful.

Why bother?

At sale — solicitors routinely ask for evidence of planning status. Without an LDC, a buyer's solicitor may require indemnity insurance (£150–£500) or ask for a reduction.
If PD rights change — an LDC locks in the lawfulness of the development at the date of issue.
Dispute resolution — if a neighbour challenges the development, an LDC is definitive evidence.

Application fee: £206 for a proposed development LDC in England (as of 2025). Determination period: 8 weeks.

Submit via the Planning Portal (planningportal.gov.uk). Include a site plan, elevation drawings, and a statement explaining how the proposed works fall within PD limits. For the full step-by-step process, see our how to apply for a Lawful Development Certificate UK guide.

Prior Approval: What the Council Can (and Can't) Consider

For extensions requiring Prior Approval under the Neighbour Consultation Scheme, the council's powers are specifically limited to:

Transport and highway impacts
Contamination risks on the site
Flood risk

The council cannot refuse Prior Approval on grounds of design, impact on neighbour amenity (beyond transport), or any other material planning consideration. This is a narrow power — which is why the Prior Approval route is generally lower risk than a full planning application for borderline extensions.

If no determination is made within 42 days of a valid application, the development may proceed without Prior Approval.