The Ultimate Guide to Permitted Development in London: Rules, Extensions & Legal Process

Last updated: 2026-06-02

Permitted development rights let you extend, convert, or alter your London home without applying for planning permission, provided the work falls inside specific size and design limits set in the Town and Country Planning (General Permitted Development) Order 2015 and its 2024 amendments. The right project under PDR can save you 8 weeks of council waiting and £258 in planning fees. The wrong project — built without realising it didn't qualify — costs five-figure enforcement remediation and blocks the sale of your house.

I run All Well Property Services across South East London and have managed planning, PDR, and Lawful Development Certificate work on over 100 projects since 2020. This guide covers what you can build under PDR in London in 2026, what's changed since the May 2024 reforms, and where London's borough-level rules quietly remove rights you'd otherwise expect to have.

What changed in 2024 (and what it means in 2026)

The biggest practical change for London homeowners: the "larger home extension" scheme — single-storey rear extensions up to 6 metres on terraced and semi-detached houses, 8 metres on detached — became permanent in May 2024. This ran as a temporary scheme from 2013 and was extended several times. It now sits alongside the standard 3m/4m PDR limits as a permanent feature, accessed via the Prior Approval process at your council.

This matters because half the search interest in "permitted development rights" is from homeowners trying to confirm whether the bigger limits still apply. They do.

The smaller standard limits (3m terrace/semi single-storey, 4m detached) don't need Prior Approval — they're pure PDR. The bigger limits (6m and 8m) need Prior Approval, which is a 42-day neighbour consultation. Either way, no full planning application.

The three things people confuse

Most readers conflate three separate processes:

	What it is	When you need it
Permitted Development (PDR)	Pre-approved right to build without planning permission, within set limits	Single-storey rear extensions up to 6/8m, loft conversions up to 40-50 m³, outbuildings, side extensions
Planning Permission	Council case-by-case approval of a specific design	Anything outside PDR — most front extensions, all mansards, conservation areas, change of use
Building Regulations	Technical sign-off that the build meets safety, structural, and energy standards	Every build, whether under PDR or full planning. Separate process.

Building Regulations is the most-missed step. You can build a fully PDR-compliant extension and still face a five-figure problem at sale time because there's no Building Control completion certificate. PDR removes the planning step. It never removes the Building Regs step.

What you can build under PDR in London (2026)

Class A: Extensions

Type	Standard PDR (no prior approval)	Larger Home (Prior Approval required)
Single-storey rear, terraced/semi	Up to 3m from original rear wall	Up to 6m from original rear wall
Single-storey rear, detached	Up to 4m from original rear wall	Up to 8m from original rear wall
Two-storey rear	Up to 3m (terraced), 3m (semi/detached) — max 7m eaves height	Not available — Two-storey limits don't extend under larger home scheme
Side extension	Single-storey, max 4m height, max half width of original house	Not available
Wraparound (side + rear)	Treated as separate single-storey rear + side under PDR	Available for the rear portion only

Other Class A limits that catch people out:

• Maximum 4 metres ridge height for single-storey extensions
• Eaves height not exceeding the eaves of the existing house
• Materials must be similar in appearance to the existing house
• Not more than 50% of the curtilage (garden + house area) can be covered by extensions and outbuildings combined — this is the limit that blocks a lot of larger second extensions
• If you've already extended under PDR, the new work counts towards your total allowance. You don't get a fresh 6m every five years.

Class B and Class C: Loft conversions

Loft conversions are PDR if:

• Total roof space added doesn't exceed 40 cubic metres for terraced, 50 cubic metres for semi-detached and detached
• No extension beyond the plane of the existing roof slope on the principal elevation (front of house)
• No higher than the highest part of the existing roof
• Side-facing windows must be obscure-glazed and non-opening below 1.7m from the floor
• Materials similar to the existing house

What's excluded:

• Mansard conversions are not PDR. They alter the roof shape and almost always need planning permission. Most South London mansards trigger Article 4 considerations too.
• Front-facing dormers are not PDR.
• L-shaped dormers on properties with rear additions can exceed 40 m³ quickly — measure carefully.

Class E: Outbuildings

Garden rooms, home offices, garden gyms, summer houses — all PDR if:

• Single storey, eaves height ≤ 2.5m, overall height ≤ 4m (dual-pitched roof) or ≤ 3m (any other roof)
• ≤ 2.5m height if within 2m of any boundary
• Not in front of the principal elevation
• Not more than 50% of garden area (combined with all other extensions/outbuildings)
• Not for sleeping accommodation (this is the rule most often broken — a "garden office" with a bed in it is no longer PDR)

Class G and H: Chimneys, satellite dishes, antennae

Minor changes — usually PDR within size limits set in the order.

What removes your PDR in London

This is where London diverges from the rest of England. Several layers can quietly strip PDR even when the project would otherwise qualify:

Article 4 directions

A council can withdraw PDR for a specific area or property type via an Article 4 direction. In London, the common ones include:

• Wandsworth: Article 4 on HMO conversions (Class C3 → C4) across most of the borough
• Lambeth: Article 4 on residential basement extensions in parts of Streatham and Brixton
• Bromley: Article 4 on changes of use in town centre conservation areas
• GLA-wide: Article 4 on office-to-residential conversion (Class O), removing the national PDR right across most of inner London
• Westminster, K&C: Article 4 on roof extensions, front extensions, basement work — varies street by street

Check the planning portal for your specific address and the council's Article 4 register before assuming PDR applies.

Conservation areas

In a conservation area, several Class A and B rights are restricted:

• Side extensions are no longer PDR
• Rear extensions are reduced to single-storey only
• Cladding is no longer PDR
• Roof extensions and dormers are no longer PDR

Around 30% of South East London sits inside a conservation area — Dulwich Village, Crystal Palace Triangle, parts of Camberwell, Blackheath, Greenwich Park. The council's online map shows boundaries.

Listed buildings

Listed building consent is required for any work that affects character, inside or out. PDR doesn't apply. This catches owners of Georgian and early Victorian properties most often.

Flats and maisonettes

PDR for extensions and roof alterations does not apply to flats, maisonettes, or any "dwellinghouse" that isn't a standalone house. Leasehold properties almost always need landlord consent on top of any planning requirement. This rules out PDR for the majority of inner-London properties.

Previous extensions counted

If the property has been extended previously — even by a previous owner, even decades ago — those extensions count against your total PDR allowance. The 50% curtilage rule and the 6m/8m rear-extension limits are cumulative.

Lawful Development Certificate: do you need one?

A Lawful Development Certificate (LDC) is the council's written confirmation that a specific project is lawful under PDR. You don't legally need one to build under PDR. You do practically need one because:

• Sale of the house. Your buyer's solicitor will ask for one for any extension or loft conversion that wasn't built with planning permission. Without it, the sale stalls.
• Enforcement protection. A council can issue an enforcement notice up to 4 years after a build is "substantially complete". An LDC issued before or during the build defeats that.
• Building Regs evidence. Some councils' Building Control teams want to see the LDC before signing off completion.

The cost and process:

• Application fee: £129 (householder LDC, 2026)
• Prep cost: £400 to £1,500 for the drawings and planning statement. A self-prepared application is possible but the council rejects ~30% of self-prepared LDCs on first submission.
• Council turnaround: 6 to 8 weeks at most London boroughs
• What's submitted: existing and proposed drawings (site plan, floor plans, elevations), supporting statement explaining how the proposal meets each PDR criterion, evidence (photos, deeds, previous decisions) where helpful

We include LDC submission as standard on every PDR project we run. The £400-£1,500 cost is rolled into the contract — clients don't pay separately for it. The certificate sits with the house when it sells.

Prior Approval: the bigger extension process

For single-storey rear extensions over 3m on terraced/semi or over 4m on detached (up to the 6m/8m PDR maximum), you need Prior Approval — not full planning, not pure PDR.

Process:

• Submit notification with drawings to the council
• Council writes to adjoining neighbours (42-day consultation)
• If no objections, the council confirms Prior Approval and the build is PDR
• If a neighbour objects, the council assesses whether the impact is acceptable — they can still approve

Fee: £108 (2026). Turnaround: typically 6 weeks. The 42-day clock is statutory.

This is a different process from a full planning application and it's much harder for a council to refuse. If you're within the 6m/8m envelope and the build is otherwise PDR-compliant, Prior Approval is usually a formality. The exception is properties where a neighbour mounts a credible "loss of light" or "loss of amenity" objection — councils take those seriously even under Prior Approval.

Building Regulations: not optional under PDR

Repeating this because it's the most-missed point in the entire process.

Building Regulations approval is separate from planning. You need it for:

• Every extension, regardless of PDR or planning
• Every loft conversion
• Every structural change (RSJs, wall removal, foundations)
• Most electrical and plumbing work
• Window replacement (FENSA or council Building Control sign-off)

You don't apply for Building Regs with the council planning department. You either:

• Use the council's Building Control service (Local Authority Building Control, LABC), or
• Use a private Approved Inspector

Either route ends with a completion certificate. That certificate is what your buyer's solicitor will ask for at sale time.

On every project we run, Building Control is set up at the start of the contract, inspected at each stage (foundations, weatherproof, first-fix, completion), and signed off before final payment. The certificate is handed over with the final paperwork.

Common reasons PDR projects fail

From projects I've assessed across South East London:

1. The cumulative limit catches the second extension. Owner extended 4m in 2010, comes back in 2026 wanting another 4m. The combined 8m exceeds the 6m PDR cap on a terraced house. Result: full planning application.
2. The "garden office" with a bed. Class E specifically excludes sleeping accommodation. The moment a garden room sleeps anyone, it's no longer PDR and needs planning.
3. The conservation area surprise. Owner is on the edge of a conservation area boundary and doesn't realise. The address postcode isn't a reliable check — use the council's online conservation area map.
4. The Article 4 strip-out. Wandsworth and Lambeth in particular have removed Class C3→C4 PDR (single dwelling to small HMO) on most of the borough. Buy-to-let conversions are caught.
5. The 50% curtilage limit. Big rear extension + garden room + side return adds up. The Class A rules cap *combined* coverage at 50% of the original garden+house area.
6. Materials don't match. A modern aluminium-clad extension on a Victorian terrace fails the "similar appearance" test. The council can issue an enforcement notice retrospectively.

What this means for your project

If your project is within PDR limits, you save 8 weeks of council waiting and £258 in planning fees. If it's outside, you face an 8-12 week planning application with a 65-75% London approval rate. Knowing which side of the line you sit on before you commit to a design is the difference between a clean build and a stalled one.

The honest assessment most homeowners need:

• A single-storey rear extension up to 6m on a non-conservation-area terraced or semi-detached London house is almost certainly PDR (via Prior Approval).
• A standard rear dormer loft conversion under 40 m³ on a non-conservation-area terraced house is PDR.
• A side extension on a non-conservation-area house with garden space is usually PDR.
• A mansard, a basement, a two-storey rear, or anything in a conservation area needs planning permission. Don't try to make it fit PDR.
• Flats and listed buildings don't get PDR for extensions or roof work.

Frequently asked questions

Do I need to tell my neighbours about a PDR extension?

For pure PDR (within the standard 3m/4m limits) — no formal requirement. For Prior Approval (3-6m terrace/semi, 4-8m detached) — the council writes to your neighbours, you don't need to. As a matter of courtesy and to head off complaints during the build, every project I run starts with a printed letter through the immediate neighbours' doors a week before site setup.

Can I build under PDR if my house is leasehold?

Possibly, but you need landlord consent on top of any planning requirement. The freeholder's lease usually contains a clause requiring written consent for structural changes. Without consent, PDR compliance is irrelevant — the lease blocks you. Most South London leases on Victorian conversions require landlord consent for any external alteration.

How long does an LDC take in London?

6-8 weeks at most boroughs. Bromley, Lewisham, and Lambeth are typically 6-7 weeks. Wandsworth, Lambeth, and Southwark can stretch to 8-10 weeks. Westminster and K&C run longer. Submit early — you want the LDC issued before you start the build.

Does PDR work on a flat?

Most extension and roof PDR rights don't apply to flats. Internal alterations and some window changes may still fall under PDR, but anything that changes the external envelope of a flat needs planning.

Do I need a structural engineer for a PDR extension?

For Building Regulations, yes — any beam, foundation, or load-bearing change needs structural calcs. The structural engineer is separate from the architect or designer. On a typical 4m single-storey rear extension expect £600-£1,200 for the structural design package.

What's the difference between PDR and Prior Approval?

Pure PDR (3m/4m single-storey rear and smaller) is automatic — you can build without any council involvement (though an LDC is strongly recommended). Prior Approval (3-6m terrace/semi, 4-8m detached single-storey rear) requires submitting a notification and a 42-day neighbour consultation. Both result in a build without full planning permission.

Can I extend if I'm in a conservation area?

Yes, but with reduced PDR. No side extensions, no two-storey rear extensions, no roof extensions under PDR. A single-storey rear extension up to 3m is still PDR. Anything bigger requires full planning. Material choices are scrutinised — most conservation areas require like-for-like brick, sash windows, and slate roofing on visible elevations.

Will I get an enforcement notice if I build outside PDR by mistake?

You can — councils have 4 years from substantial completion to issue an enforcement notice for unauthorised development. The remedy is usually demolition or a retrospective planning application. An LDC issued at the time of build defeats this.

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Need a structural opinion before you commit?

We do free site visits across 25 South East London boroughs and the assessment includes a walkthrough of whether your project is PDR, Prior Approval, or full planning — *before* you commit to a designer or a build. Same director-led process: one project manager, fixed-price contract, LDC and Building Control sign-off included.

Call 020 3920 9617, use the contact form, or send a WhatsApp. Free site visit within 5 working days, itemised written quote within a further 5. NICEIC, FENSA, CHAS, Gas Safe — registered against Companies House No. 12721034.