Permitted Development Rights 2026: What You Can Build Without Planning Permission

What are permitted development rights?

Permitted development rights (PD rights) are a set of national planning rules that grant automatic permission for certain types of building work on houses in England. They exist so that homeowners can carry out reasonable improvements without the cost, delay and uncertainty of a full planning application. In 2026, PD rights remain the most common route for UK home extensions, loft conversions, outbuildings and garage conversions.

PD rights are not a blanket free-for-all. They come with strict conditions on size, height, materials, position relative to boundaries and the original house footprint. Breach any of those conditions and the work is technically unlawful - which creates enforcement risk, insurance issues and serious problems when you sell. Understanding the limits is just as important as knowing the freedoms.

At RCB Design & Build, the first check we run on every project is whether the proposed work falls within permitted development. As FMB and TrustMark accredited contractors working across London and the South-East, we have delivered hundreds of PD projects and know exactly where the boundaries lie. This guide sets out the 2026 rules in plain English so you can plan with confidence.

Single-storey rear extensions under PD

Single-storey rear extensions are the most common use of permitted development rights and the rules are straightforward once you know the numbers. For detached houses the maximum depth is 4 metres from the original rear wall. For semi-detached and terraced houses the limit is 3 metres. These are the standard PD limits that have been in place for years.

The Larger Home Extension scheme (also called the neighbour consultation scheme or prior approval route) allows deeper extensions: up to 8 metres for detached houses and 6 metres for semi-detached and terraced properties. This is not automatic PD - you must submit a prior approval application to the council, and adjoining neighbours are formally notified. If no objections are received within 21 days, prior approval is granted. If neighbours object, the council makes a judgement based on the impact on their amenity. The application fee is currently GBP 120 and the determination period is 42 days.

In all cases, the eaves height of the extension must not exceed 3 metres. Where the extension is within 2 metres of a boundary, the maximum eaves height is also 3 metres and the overall height must not exceed 4 metres for a flat roof or the height of the existing eaves for a pitched roof. Materials should be similar in appearance to the existing house. These conditions trip up more homeowners than the depth limits themselves.

At RCB Design & Build, we handle prior approval applications as part of our standard pre-construction service. Our Checkatrade reviews consistently mention the smooth planning process as a key benefit of working with us.

Side extensions, two-storey extensions and outbuildings

Side extensions under PD must not exceed 50% of the width of the original house (measured from the side wall facing the highway). They are limited to single storey, must not extend beyond the front elevation of the original house, and the same height limits apply as for rear extensions. Materials must match the existing house.

Two-storey extensions have tighter PD limits. They are allowed at the rear only (not the side), must not extend more than 3 metres from the original rear wall, must not be within 7 metres of the rear boundary, and the eaves and ridge must not exceed the height of the existing house. All upper-floor windows in a side elevation must be obscure-glazed and non-opening (unless the opening part is more than 1.7 metres above the floor). The roof pitch must match the existing house.

Outbuildings - garden offices, studios, gyms and workshops - are permitted under PD provided they are single storey, do not cover more than 50% of the garden area, are not forward of the principal elevation, and do not exceed 2.5 metres in height if within 2 metres of a boundary (or 4 metres with a dual-pitched roof / 3 metres with any other roof type elsewhere in the garden). They must be used incidentally to the enjoyment of the dwelling - not as a separate dwelling or for commercial purposes.

These limits create genuine opportunities. A well-designed garden office under PD can cost GBP 15,000-GBP 40,000 and adds both functional space and property value. We design outbuildings that maximise the PD allowances while complementing the main house.

Loft conversions under permitted development

Loft conversions are one of the most valuable uses of PD rights in London and the South-East. The key limits in 2026 are: an additional roof volume of 40 cubic metres for terraced houses or 50 cubic metres for semi-detached and detached houses. The volume calculation covers the total enlargement to the original roof, including any previous additions.

Dormers are permitted at the rear under PD but not on the front or side elevations facing a highway. Dormer materials must be similar to the existing house. The dormer must not extend beyond the plane of the existing roof slope facing any highway, must be set back at least 200 mm from the original eaves, and the highest point of the dormer must not exceed the highest point of the existing roof.

Roof windows (Velux-style) on the front elevation are permitted provided they do not project more than 150 mm beyond the existing roof plane. Hip-to-gable alterations on detached and semi-detached houses fall within PD in most cases, though some boroughs interpret the rules differently - always check.

Mansard conversions rarely fall within PD because they alter the roof shape so substantially. If you want a mansard, plan for a full planning application. At RCB Design & Build, we have extensive experience with both PD loft conversions and full planning applications across every London borough and the Kent commuter belt.

When permitted development rights are removed or restricted

Not every property benefits from the full set of PD rights. Several situations restrict or remove them entirely. Conservation areas restrict PD rights for side extensions, rear extensions beyond the principal elevation, cladding, satellite dishes and dormer additions to the roof slope facing a highway. Article 4 directions go further - local authorities can withdraw specific PD rights on a street-by-street or area-wide basis. Many London boroughs operate Article 4 directions covering front gardens, dormers, basement excavation and even paint colours.

Listed buildings have no PD rights for any work that affects the character of the building - which in practice means almost any alteration, internal or external, requires listed building consent in addition to any planning permission. Flats and maisonettes have no PD rights for external alterations. Properties where a condition on the original planning permission removed PD rights (common on new-build estates) are also restricted.

If your property has previously been extended, the earlier extensions count against the PD allowances. A house that already has a 2-metre rear extension under PD can only extend a further 1 metre (on a semi-detached) before hitting the 3-metre limit. Previous loft volume additions count against the cubic metre allowance. The calculation is always measured against the original house as it stood on 1 July 1948 or when it was first built if later.

Before designing anything, we check the council planning constraints map, search for Article 4 directions, and verify the property has not already consumed its PD allowances. This 30-minute check at the start prevents weeks of wasted design time.

Lawful Development Certificates: essential protection

Even when your project genuinely falls within permitted development, we strongly recommend applying for a Lawful Development Certificate (LDC) from your local council. An LDC is the council's formal written confirmation that your specific project does not require planning permission. It costs GBP 129 (half the cost of a full planning application) and the council has eight weeks to determine it.

Why bother? Two reasons. First, it protects you against future enforcement action. Councils can and do investigate building work, sometimes years after completion. An LDC provides definitive proof that the work was lawful at the time it was carried out. Second, it provides a clean answer when you sell. Without an LDC, conveyancing solicitors routinely raise queries about extensions and loft conversions that were built without planning permission. These queries delay sales by weeks and sometimes require expensive indemnity insurance policies.

The LDC application requires the same drawings you would need for Building Regulations anyway - existing and proposed floor plans and elevations - so the additional cost and effort is minimal. We submit LDC applications as standard on every PD project we deliver. It is one of those small investments that pays for itself many times over when the time comes to sell.

If you are planning any building work and want to understand whether it falls within permitted development, contact RCB Design & Build for a free project review. We will check your property's PD status, advise on the best route for your project, and handle all applications as part of our pre-construction service.

Change of use and commercial permitted development

PD rights extend beyond physical extensions to changes of use. In 2026, the most relevant change-of-use PD rights for residential properties include converting agricultural buildings to dwellings (Class Q), converting commercial premises to residential (Class MA, which replaced the old Class O for office-to-residential conversions), and using part of a dwelling for a home business provided it remains primarily a home.

Class MA allows conversion of shops, offices, light industrial units, restaurants and other commercial uses to residential dwellings via prior approval. The building must have been in its current use for at least two continuous years, the unit must not exceed 1,500 m², and the local authority assesses the proposal against specific criteria including flooding, contamination, transport impact and the impact on the sustainability of local services.

For homeowners, the most common change-of-use question is whether working from home requires planning permission. In general, using part of your home as a home office does not require permission provided the primary use of the property remains residential. If the business generates significant vehicle movements, customer visits, noise or deliveries that change the character of the property, planning permission may be needed. A garden office under PD rules (see outbuildings above) must be incidental to the residential use of the dwelling - it cannot be a standalone commercial premises.