Planning Permission vs Permitted Development — What's the Difference?

Permitted Development (PD) Rights are a set of rules that allow certain types of building work to proceed without a full planning application. These rights are granted by the government through the Town and Country Planning (General Permitted Development) (England) Order 2015 (GPDO). They are designed to reduce the administrative burden on local councils and allow homeowners to make reasonable improvements to their homes.

PD rights exist for extensions, loft conversions, outbuildings, porches, solar panels, satellite dishes, and several other categories. Each type of work has specific conditions — on size, height, materials, and proximity to boundaries — that must be met for the work to qualify.

Planning Permission is the formal consent granted by the Local Planning Authority (LPA) — your local council — that allows you to carry out development work. A full planning application must be submitted with drawings, a site plan, a design statement, and supporting documentation. The council has eight weeks (or thirteen weeks for major applications) to decide.

Not all applications are approved. The planning authority will consider the impact on neighbours, the character of the area, highways, overshadowing, and a range of other factors. Conditions may be attached to any approval.

Most residential loft conversions in England fall within Permitted Development, subject to volume and design limits. The key limits are:

• •Terraced houses: up to 40 cubic metres of additional roof space
• •Detached and semi-detached houses: up to 50 cubic metres of additional roof space
• •The materials used must be similar in appearance to the existing house
• •No extension beyond the plane of the existing roof slope at the front (facing a highway)
• •The highest part of the extension must not be higher than the highest part of the existing roof
• •No verandas, balconies or raised platforms
• •Side-facing windows must be obscure-glazed and non-opening below 1.7m from floor level

Hip-to-gable conversions on semi-detached properties typically fall within PD. Rear dormers on terraced houses are the most common PD loft conversion. Mansard conversions on terraced houses usually require full planning permission.

Single-storey rear extensions fall within Permitted Development up to specific depths:

• •Terraced and semi-detached houses: up to 4 metres depth (or 6 metres under the Prior Approval neighbour consultation scheme)
• •Detached houses: up to 8 metres depth (or 8 metres under Prior Approval)
• •Maximum height: 4 metres (or 3 metres within 2 metres of a boundary)

For extensions beyond these limits under the Prior Approval scheme (4–6m for terraced/semi, 4–8m for detached), you must notify the council and allow a 42-day neighbour consultation period. This is not planning permission — it is a different process.

Side extensions require planning permission if they are more than half the width of the original house, or if they are on a corner plot.

Planning permission is always required in the following cases:

• •The property is in a Conservation Area, National Park, Area of Outstanding Natural Beauty, or World Heritage Site (PD rights are restricted or removed)
• •The property is a listed building (all works require Listed Building Consent in addition to or instead of planning permission)
• •The property is a flat or maisonette (PD rights do not apply to flats)
• •The work has already used up the PD allowance
• •The scale or design exceeds PD limits
• •The local council has removed PD rights via an Article 4 Direction (common in Conservation Areas)
• •The extension is on the side elevation in a Conservation Area

Always check whether your property is in a Conservation Area or subject to an Article 4 Direction before assuming PD applies.

A Lawful Development Certificate (LDC) is a formal document issued by the council confirming that the proposed work is lawful — i.e., it falls within Permitted Development or is otherwise lawful without planning permission. It is not planning permission, but it is valuable:

• •It provides certainty that the work is legal
• •It is required by solicitors in property sales
• •It protects you if the council later challenges the work
• •Mortgage lenders sometimes require it

We strongly recommend obtaining an LDC before starting PD work. It takes 6–8 weeks and currently costs £206 per application in England. RCB works with planning consultants who manage this process.

If your property is in a Conservation Area, Permitted Development rights are significantly restricted:

• •Any side extension that fronts a highway requires planning permission
• •Any cladding of the exterior with stone, artificial stone, pebble dash, render, timber, plastic or tiles requires planning permission
• •Larger rear extensions (over 4m for detached, 3m for other) require planning permission
• •Roof alterations visible from a highway require planning permission

More than 10,000 Conservation Areas exist in England. You can check whether your property is within one on your local council's website or via Historic England's online map.