Planning · Updated May 2026

Do I Need Planning Permission for a Kitchen Extension in 2026? (UK)

Q: Can I knock through to make a kitchen-diner under PD?

Internal knock-through is building control, not planning. Only the extension triggers planning.

Q: Do bifolds or lanterns affect planning?

Not directly under PD, but conservation areas often refuse large bifold glazing — check pre-app.

Q: Does a flat roof count as 4m?

Yes, measured from natural ground to the highest point. Most flat-roof kitchens sit at 3.0–3.2m.

Q: Will my neighbours stop my Larger Home Extension?

Objections must be on amenity grounds (light, overlooking). Aesthetics are not valid. Most objections fail if the build is PD-compliant.

Q: Do I still need building control with PD?

Yes — PD covers planning only. Building control is a separate mandatory process.

A single-storey kitchen extension at the rear of a UK home is usually permitted development in 2026 if the depth is under 4m (detached) or 3m (semi/terraced), height is under 4m, and it's not on designated land. Between 3–8m depth (semi) or 4–8m (detached) you need the Larger Home Extension prior-approval route — a 42-day neighbour-notification process, not full planning. Side-return widens beyond 50% of the original house width? Full planning. Two storeys? Full planning. This guide walks the exact PD limits, the Larger Home Extension flow, and the Lawful Development Certificate that protects you at sale.

PD depth limits Larger Home Extension route Neighbour notification

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Researched, written & fact-checked. Reviewed 17 May 2026. How we research & fact-check

PD Rules

The 6 Conditions That Keep a Kitchen Extension Under PD

1. Depth limits

Standard PD: 3m semi/terrace, 4m detached. Larger Home Extension (prior approval): up to 6m semi, 8m detached. Beyond that = full planning.

2. Single-storey only

Two-storey rear extensions need full planning. So do rooms-in-roof above the extension, and dormers from the back of the new build.

3. Height limits

Max 4m to ridge. Within 2m of a boundary: 3m to eaves. Flat-roof kitchens are usually 3m tall — fine for PD.

4. Width & coverage

Combined with any earlier extensions, the new build can't cover more than 50% of the original garden. Side-return + rear = check the total.

5. Materials must match

Brick, render and roof tile must match (or closely resemble) the existing house. Modern glazed kitchen extensions in old houses usually need full planning.

6. No designated land or Article 4

Conservation areas, AONBs, National Parks and Article 4 streets all reduce or remove kitchen-extension PD. Check the planning map first.

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Frequently Asked

Common Questions

What is the Larger Home Extension prior-approval route?+

A streamlined PD route for single-storey rear extensions 3–6m deep (semi) or 4–8m deep (detached). Costs £103, takes 42 days. The council notifies neighbours; if no valid objection, it's approved.

Can I knock through to make a kitchen-diner under PD?+

Internal knock-through is not planning at all — it's building control (load-bearing wall = structural engineer + steel calcs). The extension itself is what triggers planning, not the internal layout.

Do bifolds, lanterns or a flat roof affect planning?+

Not directly under PD, as long as overall height and depth are within limits. But conservation areas often refuse large bifold glazing — check pre-app.

Does a flat roof count as 4m high?+

Yes, measured from natural ground to the highest part of the roof structure (including parapet). Most flat-roof kitchen extensions are 3.0–3.2m — comfortably under.

Will my neighbours stop my Larger Home Extension?+

They can object, but only on grounds of "impact on amenity" — loss of light, overlooking. Aesthetics or "I don't like it" are not valid. Most objections fail when the build meets PD limits.

Do I still need building control with PD?+

Yes. PD covers planning only. Building control approval is a separate, mandatory process for structural, fire, drainage and thermal performance.

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