When Do You Need Planning Permission in the UK? Complete 2026 Guide

The short answer

You probably don’t need full planning permission if your project sits inside the limits of the General Permitted Development Order 2015 (GPDO) — the statutory instrument that grants you automatic permission for routine domestic alterations. You almost certainly do need it if you are extending upward, fronting a highway, working on a Listed Building, sitting in a Conservation Area, or operating under an Article 4 direction.

The rule of thumb is this: if you can imagine a neighbour having a reasonable objection — loss of light, loss of privacy, change of character of the street, increased traffic — you almost certainly need a planning application. If the work is invisible from the street and within ordinary domestic scale, you’re probably PD. When in doubt, file a Lawful Development Certificate (£129 in 2026) before you build; it’s the only way to bank legal certainty.

How UK planning actually works

The UK planning regime is set by the Town and Country Planning Act 1990 (TCPA), as amended by every Government since. Two concepts do most of the heavy lifting for homeowners:

Planning permission is the principle of consent. Every “operational development” (which means construction, demolition, mining, or other physical alteration to land) requires planning permission unless the GPDO grants it automatically. Planning permission is decided by your Local Planning Authority (LPA) — usually the District, Borough, City or Unitary Council. London has 32 Borough Councils + the City of London; outside London, it’s whichever council you pay Council Tax to (or, in two-tier areas, the District Council, not the County).

Permitted Development (PD) is the statutory shortcut. Article 3 of the GPDO 2015 grants automatic planning permission for a wide range of routine domestic alterations — subject to limits, conditions and exclusions. If your project stays inside the limits, you don’t need to ask. If any limit is breached, PD falls away entirely and you need a full householder application.

The PD regime is set out in Schedule 2 of the GPDO 2015, split into Parts. For domestic properties, Part 1 (Classes A through H) covers most homeowner work; Part 2 covers minor operations; Part 14 covers renewable energy installations.

Permitted Development by Class — the homeowner cheat sheet

The eight PD classes most homeowners encounter are summarised below. Every figure is from the GPDO 2015 as amended through 2026.

Class A — extensions and alterations

The most-used PD class. Covers rear extensions, side extensions, and most external alterations. The headline limits for a single-storey rear extension on a detached house:

• Maximum depth from the original rear wall: 8 metres (detached), 6 metres (terraced or semi) under the “larger home extension” prior approval route; 4 metres (detached) / 3 metres (other) under the default rule.
• Maximum height: 4 metres for any extension within 2 metres of a boundary; 4 metres overall otherwise.
• Eaves height (single-storey): not more than 3 metres if within 2m of a boundary.
• Materials: must be of similar appearance to those of the existing house.
• Original curtilage occupied: not more than 50% of the curtilage (everything that isn’t the original house) can be covered by extensions and outbuildings combined.
• Not in front of the principal elevation fronting a highway.

Two-storey extensions under Class A are limited to: maximum depth 3 metres from the original rear wall; not less than 7 metres from the rear boundary; maximum eaves and ridge heights matching the original house.

Side extensions are tightly limited under Class A: must be single-storey, maximum height 4 metres, maximum width half the width of the original house, materials similar to the original. Two-storey side extensions are not PD and always require a householder application.

Class AA — upward extensions (added 2020)

Added in 2020 to encourage densification, Class AA permits the addition of one or two extra storeys to a detached, semi-detached or terraced house, subject to prior approval (not full planning). Tight limits apply: maximum 18m total building height; the new floor cannot extend beyond the existing footprint; materials must be similar; and prior approval is needed for design, external appearance, amenity impact, and impact on neighbouring properties. Most LPAs scrutinise Class AA heavily — in practice it’s closer to a householder application than to standard PD.

Class B — roof alterations

Loft conversions. Class B permits roof extensions (e.g. rear dormers) up to 40 m³ for terraced houses and 50 m³ for detached / semi-detached, subject to:

• No part of the extension to project forward of the plane of the existing roof slope fronting a highway.
• No part to be higher than the highest part of the existing roof.
• Materials similar to the existing house.
• Cladding (where required): tile-hanging, vertical timber or render to match.
• Side-facing windows obscure-glazed and non-opening below 1.7m.

Loft conversions that don’t add volume (i.e. no dormer, no raised ridge, just internal conversion plus conservation-style rooflights) typically don’t even need Class B — they’re internal works that don’t engage planning at all. You still need Building Regulations approval.

Class C — minor roof alterations

Rooflights, solar PV, solar thermal — provided they don’t project more than 150mm beyond the roof plane, don’t exceed the highest part of the roof, and (for rooflights) don’t front a highway.

Class D — porches

A porch is PD if: floor area ≤3 m²; height ≤3 m above ground level; and no part within 2 metres of any boundary that fronts a highway. Most front porches fall comfortably inside Class D.

Class E — outbuildings and curtilage structures

Sheds, summer-houses, garden offices, swimming pool houses, kennels, greenhouses. Class E limits: single-storey; maximum eaves height 2.5m; maximum overall height 4m (dual-pitched roof) or 3m (other); not in front of the principal elevation; not more than 50% of total curtilage covered (combined with extensions). For a Class E outbuilding within 2 metres of a boundary, the overall height is capped at 2.5m.

Garden offices used as primary places of work technically fall under Class E if used “in connection with the dwellinghouse” (e.g. incidental home working), but become a planning issue if they’re used for a separate business with visiting clients or staff.

Class F — hard-surfacing of front gardens

Hard-surfacing more than 5 m² of front garden requires planning permission UNLESS the new surface is porous (gravel, permeable block paving) or directs water to a permeable area. The intent is flood management.

Class G — chimneys, flues and soil-and-vent pipes

Generally PD unless the property is in a Conservation Area, in which case Class G is excluded and you need permission.

When PD doesn’t apply — the exclusions

Even if your project sits inside the numerical limits, Permitted Development falls away in five categories of property. Check these before assuming Class A,B,C or E applies.

• Flats and maisonettes. Schedule 2 Part 1 only applies to a “dwellinghouse”. A flat is not a dwellinghouse for PD purposes. Flat owners need permission for almost every external alteration, and leasehold consent from the freeholder besides.
• Listed Buildings. Any work to the fabric of a Listed Building requires Listed Building Consent (LBC) under the Planning (Listed Buildings and Conservation Areas) Act 1990. LBC is free to apply for, but the case is decided on conservation merits and historic England may be consulted. Refusal rates are high.
• Conservation Areas. Classes A (rear extensions over 50% original) and Class E (outbuildings to front or side) are excluded in CAs. Article 4 directions often layer further restrictions.
• National Parks, AONBs, Norfolk Broads, World Heritage Sites. The “designated areas” carve-out under Article 1(5) of the GPDO removes most PD rights.
• Article 4 areas. The LPA can withdraw any specific PD class within a defined geographic boundary. Inner London boroughs use these heavily; check the council’s planning portal.

The Lawful Development Certificate — your safety net

A Lawful Development Certificate (LDC) is a binding determination by the LPA that your proposed development is, in their view, Permitted Development. It costs £129 in 2026 (half the householder application fee), is decided within 8 weeks, and once granted is good for life on that exact scheme.

Why bother if PD is automatic? Three reasons:

• Conveyancing. Selling the house in five years’ time, the buyer’s solicitor will ask for proof that the extension was lawful. Without an LDC, you’re stuck either trying to evidence PD compliance years later (hard) or buying expensive lack-of-consent indemnity insurance.
• Lender. Buy-to-let and remortgage lenders increasingly demand LDC evidence for any post-2015 extension before drawing down.
• LPA dispute. If the planning enforcement officer comes calling because a neighbour reported the work, an LDC is your binding defence. Without one, you’re arguing PD compliance from scratch.

An LDC takes the same 8-week determination period as a full application but is decided on objective criteria rather than planning judgement. The success rate is roughly 75%; refusal usually means a numeric limit was breached.

The householder planning application — when PD doesn’t fit

When you need full planning permission, the route is a Householder Planning Application lodged via the Planning Portal (planningportal.co.uk) or directly with your LPA. The 2026 fee is £258 (rising to £293 from 1 October 2026). The statutory determination period is 8 weeks from the date of validation.

What gets submitted:

• Application form (10HH form via Planning Portal).
• Location plan (1:1250 OS).
• Block plan (1:200 or 1:500).
• Existing and proposed elevations (1:50 or 1:100).
• Existing and proposed floor plans (1:50 or 1:100).
• Roof plans if relevant.
• Design and Access Statement (mandatory in Conservation Areas, optional elsewhere).
• Application fee.

You can DIY a simple householder application, but most people instruct an architect or planning consultant for the drawings (£1,800–£4,500 typical for a residential extension package). The drawings need to be to the right scale, in the right format, and the LPA validation team will reject anything sub-standard.

The decision. Most householder applications are decided under delegated powers by the planning case officer (i.e. no committee, no public hearing). Roughly 5–10% get called to committee if there are substantial objections or sensitive issues. The 2026 national approval rate for householder applications is roughly 89% — you are very likely to be approved unless your proposal is manifestly contrary to local policy.

Article 4, Conservation Areas, Listed Buildings

Three overlay designations add complexity. Check each one before assuming PD.

Article 4 directions are local authority orders that withdraw specified PD rights from a defined area. They were originally rare but proliferated in the 2010s as LPAs sought to protect local character. Hackney, Islington, Westminster, Kensington & Chelsea, Camden, Wandsworth and the City of London have extensive Article 4 networks. Phone the LPA’s planning enquiries line and ask explicitly: “is X address in an Article 4 area, and if so which Classes are withdrawn?”

Conservation Areas are designated under §69 of the Planning (Listed Buildings and Conservation Areas) Act 1990. They impose specific additional consents: Conservation Area Consent for most demolition; restrictions on materials and design; tree-related work requires 6 weeks’ written notice to the LPA before any pruning, lopping, felling or uprooting of any tree over 7.5cm trunk diameter.

Listed Buildings require Listed Building Consent (LBC) for any alteration that affects the special architectural or historic interest. LBC is free, decided in 8–12 weeks, and refusal is more common than for planning — especially for Grade I and II* listings. Internal alterations to a Listed Building usually need LBC even if no external work is proposed; this surprises homeowners.

Building Regulations — separate, mandatory, often missed

Even when planning permission isn’t needed, Building Regulations approval almost certainly is. The two regimes are completely separate; Building Regs are administered by Building Control under the Building Act 1984 and the Building Regulations 2010 (as amended).

Building Regs notification is required for: any extension over a single covered area; loft conversions (always); garage conversions (if used as habitable space); structural alterations (load-bearing wall removals, RSJ installations); new windows or doors; replacement boilers; rewires; replumb of any new pressurised system.

Fees: £400–£850 typical for a residential extension. You can use the local council Building Control team OR a privately-appointed Approved Inspector (the AI route is faster but more expensive). Completion Certificate is what conveyancing solicitors ask for on resale.

Party Wall Act — when your work affects a neighbour

The Party Wall etc. Act 1996 sits parallel to planning. It applies whenever you propose to:

• Work on an existing party wall (e.g. removing a chimney breast on a shared wall).
• Build a new wall on or astride a boundary.
• Excavate within 3 metres of a neighbouring building’s foundations to a depth lower than those foundations.
• Excavate within 6 metres at a 45-degree angle below the neighbouring foundations.

Procedure: serve a Party Wall Notice on the adjoining owner(s) at least 2 months before works start. Neighbours can consent (no further action), object (a Party Wall Award is then prepared by an agreed surveyor or two surveyors), or fail to respond (deemed dissent — the Award route applies). Surveyor fees are paid by the building owner: typical cost £800–£2,500 per neighbour.

Pre-application advice — worth the spend

Most LPAs offer a pre-application advice service: you pay £150–£800 (depending on the council and project scale), submit an outline of your proposed scheme, and get a written response from the case officer indicating whether the application is likely to be supported. The written response is non-binding but in practice case officers rarely contradict themselves at the application stage.

For any complex project — Article 4 areas, Conservation Areas, Listed Buildings, two-storey extensions in tight gardens, or anything you suspect the LPA might refuse — pre-app is almost always worth the spend. The refusal rate on schemes that have been through pre-app is significantly lower than cold applications.

Appeals — Planning Inspectorate

If your application is refused, you have 12 weeks from the decision date to appeal to the Planning Inspectorate (PINS). Householder appeals are decided on written representations only (no hearing, no inquiry) and typically take 16–22 weeks. There is no fee.

The 2026 national success rate on householder appeals is roughly 35%. Before appealing, consider whether a resubmitted application addressing the refusal reasons would be cheaper and faster (one free resubmission within 12 months is the standard LPA concession). Appeal only when refusal grounds are weak, the development is policy-compliant, and you genuinely believe the case officer got it wrong.

Frequently asked questions

Do I need planning permission to extend my house in the UK?

Usually not, if the extension stays inside Permitted Development limits. Single-storey rear extensions on detached houses up to 8m deep (4m for terraced/semi), maximum 4m high, made of materials similar to the host building, occupying no more than 50% of the original curtilage, do not require a planning application. Larger extensions, two-storey extensions, and any extension fronting a highway always require a householder planning application. Confirm with a Lawful Development Certificate (£129) before building.

How long does UK planning permission take in 2026?

A householder planning application takes 8 weeks for a decision under the statutory determination period (Town and Country Planning Act 1990 §78). Add 2–3 weeks for validation, 3–4 weeks for design and submission. Realistic total from architect instruction to permission granted: 14–17 weeks. Article 4, Conservation Area or Listed Building consents add a further 6–10 weeks. A Lawful Development Certificate is faster (4–8 weeks) because it doesn't go to committee.

How much does a UK planning application cost in 2026?

Householder planning application: £258 (rising to £293 from 1 October 2026). Lawful Development Certificate: £129. Listed Building Consent: £0 (free). Pre-application advice: £150–£800 depending on LPA. Add £1,800–£4,500 for architect drawings and a planning consultant if needed. Total realistic spend on the planning stage for a typical UK extension: £3,500–£7,500.

What is the difference between planning permission and Building Regulations?

Planning permission is about whether you can build the thing — does it fit the local plan, does it harm the neighbours, does it preserve the character of the area. Building Regulations are about whether the thing you've built is safe to use — structural integrity, fire safety, electrical safety, energy efficiency, accessibility. They are completely separate regimes administered by different authorities. You can need one and not the other, or both. Most extensions need both.

What is an Article 4 direction and does it apply to me?

An Article 4 direction is a local authority order that withdraws specified Permitted Development rights from a defined geographic area. Inner London boroughs use them heavily — Hackney, Islington, Camden, Westminster, Kensington & Chelsea all have extensive Article 4 areas. Historic market towns and Conservation Areas also use them. Check your council's planning portal under "Article 4 directions" or phone the planning enquiries line. If you're in an Article 4 area, you almost certainly need a planning application even for routine extensions, dormers and external alterations.

Can I appeal a refused UK planning application?

Yes. You have 12 weeks from the refusal decision to lodge an appeal with the Planning Inspectorate (PINS). Householder appeals are decided on written representations only and typically take 16–22 weeks. The success rate on householder appeals is roughly 35%. Best practice is to consult the case officer's reasons and either resubmit a revised application addressing them (cheaper, faster) or appeal only if the refusal grounds are weak (the development is policy-compliant and refusal was unreasonable).

This guide covers the planning regime in England. Scotland, Wales and Northern Ireland have similar Permitted Development frameworks but different fees, forms and statutory references. Confirm with your Local Planning Authority before relying on any of the above. Explore the rest of the guides library or jump to the renovation calculator.