How much does an LDC cost?

£103 fee plus £200–£600 consultant drawings, 8-week determination.

Planning · Updated May 2026

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

Q: Will my conservation area refuse it?

Not outright, but full planning is required and material/roof rules are stricter.

Q: Can I wrap around to a rear extension under PD?

Yes, if total rear depth and side width stay within PD or Larger Home Extension limits.

Q: Do I need a party wall agreement?

Almost always — Section 1 and Section 6 notices, costing £900–£1,800 per neighbour with appointed surveyors.

Q: Are bifolds allowed on the rear under PD?

Yes — PD has no glazing restriction. Conservation areas often require slim-line metal or timber/composite frames.

A single-storey side return extension on a UK Victorian/Edwardian terrace or semi is usually permitted development in 2026 if depth is under 3m (semi) / 4m (detached) measured from the rear wall, width is under 50% of the original house width, height is under 4m, and the property isn't in a conservation area, Article 4 zone, or designated land. Wider than 50% original width = full planning. Two-storey side return = full planning. Conservation areas almost always need full planning even for PD-compliant builds. This guide walks the rules, the conservation-area workaround, and the LDC route.

PD limits explained Conservation triggers LDC at sale

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PD Rules

The 6 Things That Decide Side Return PD Status

1. Side return width

Filling in the existing side-return alley is PD only if total side-extension width stays under 50% of the original house width. Most Victorian terraces sit just inside that limit.

2. Rear depth

If the side return wraps to a rear extension, total rear depth must be under 3m (semi/terrace) under standard PD, or 6m under Larger Home Extension prior approval.

3. Single-storey only

PD covers single-storey side returns only. Two-storey or roof-conversion-linked builds need full planning regardless of dimensions.

4. Roof & rooflight rules

Flat roof at 3m is fine. Lanterns and rooflights are usually PD if under 150mm proud of the slope. Side-facing windows must be obscure-glazed within 1.7m of the floor.

5. Conservation areas

Most London conservation areas (especially Article 4 streets) refuse side returns under PD. Expect full planning + £200–£600 design-and-access statement.

6. Party walls

PD doesn't change Party Wall Act obligations. Serve notices 2 months before start. Most side returns trigger Section 1 (new wall on the line) and Section 6 (excavation within 3m).

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Frequently Asked

Common Questions

What is a side return extension?+

An infill build along the side alley of a Victorian/Edwardian terrace or semi, typically widening the kitchen to the full width of the original house. Most common London/SE extension type.

Will my conservation area refuse it?+

Not usually outright — but they require full planning and care over materials. Brick must match, ridge/roof shouldn't be visible from street, rooflights flush only.

Can I wrap around to a rear extension under PD?+

Yes, provided the total rear extension depth stays within PD or Larger Home Extension limits, and total width stays within 50% of original house width.

Do I need a party wall agreement?+

Almost always yes — serving the Party Wall Notice and either getting written consent or appointing surveyors costs £900–£1,800 per affected neighbour.

Are bifolds allowed on the rear under PD?+

Yes for PD, no restriction on glazing area. Conservation areas often require a slim-line metal frame and timber/composite alternative.

How much does a Lawful Development Certificate cost?+

£103 application fee, plus £200–£600 for a planning consultant to prepare drawings and write-up. 8-week determination.

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