Planning guide

Rear-extension planning research

Rear-extension prospects depend on scale, design, property type and neighbour impact. Compare depth, height and boundary relationships with genuinely similar local decisions and check whether permitted-development or prior-approval routes are relevant.

Written and reviewed by Propeteer Research TeamPublished 29 July 2026Reviewed 29 July 2026

At a glance

Compare: Depth, height, width and boundary relationship
Frequent issues: Daylight, outlook, massing and design
Possible routes: Planning permission, prior approval or permitted development

A reliable process

How to approach the question.

01Measure the existing and proposed footprint and height.
02Check constraints and whether permitted-development rights remain.
03Compare terrace, semi-detached or detached precedents separately.
04Read conditions and refused examples for neighbour-impact thresholds.

Worked example

A full-width terrace-house extension

A three-metre scheme on a similar terrace may carry more weight than a six-metre detached-house approval nearby. Boundary position and the neighbour’s openings can change the effect even at the same depth.

What this does not prove

Local precedents do not override site-specific judgement.
Permitted-development rules contain detailed limits and conditions.
Planning research does not replace measured design or daylight advice.

Method used

Confirm the subject property and distinguish applications at the address from wider local context.
Classify proposal type and outcome consistently, keeping pending, withdrawn and approved-with-conditions cases separate.
Give more weight to recent, similar and well-documented decisions; retain contradictory evidence rather than hiding it.

Primary sources and official guidance

Planning PortalPlanning Portal Local planning authority registersUK local planning authorities

Source scope, licensing, refresh expectations and known limitations are listed in the public data-source register.

Related guides