Rear extension planning drawings

Rear extension plans and planning applications

Planning drawings for a rear extension show the existing house, the proposed extension, a site plan and a location plan, drawn to scale from a measured survey. We prepare them, submit the householder application, deal with the planning officer and, once approved, carry the same design through to Building Regulations drawings and the build.

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Printed floor plan and elevation drawings of a rear extension with a scale rule, tape measure and pencil

What drawings does a rear extension need?

A location plan (1:1250), a block or site plan (1:500 or 1:200), existing and proposed floor plans, and existing and proposed elevations, usually at 1:100 or 1:50. Sections help for two-storey and glass-heavy schemes. Some councils also want a design statement in conservation areas and a heritage statement for listed buildings.

What do planning drawings cost?

Allow £1,000–£2,500 including VAT for a single-storey rear extension and £2,000 to £3,500 for a two-storey scheme, covering the measured survey, design options and the application. A householder planning application in England costs £548 (£575 for applications made from 8 December 2026), and a lawful development certificate for proposed work costs half the householder fee.

When do you need a full application?

A two-storey rear extension can be permitted development in England only if it projects no more than 3 metres, stays at least 7 metres from the rear boundary, matches the existing roof pitch and has obscure-glazed upper side windows. In practice most double-storey rear extensions go through a householder planning application.

Wraparounds, extensions in conservation areas, anything deeper than the permitted development or prior approval limits, and homes whose rights have been removed all need a householder application.

How long does planning take?

Councils aim to decide householder applications within 8 weeks of validation, and prior approval within 42 days.

Different rules in Wales, Scotland and Northern Ireland. The limits above are for England. Check your own house with our depth checker or read how far you can extend without planning.

What is included?

Measured survey
Two or three design options
Planning drawings to scale
Location and site plans
Application forms and fee
Liaison with the planning officer
Conditions discharged
Building Regulations drawings to follow

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FAQ

Rear extension planning drawings questions

Do I need an architect?

You need accurate drawings by someone who knows householder planning; we provide them.

Can I see the design in 3D?

Yes; we produce simple 3D views so you can judge the size and light.

What if planning is refused?

We review the reasons with you, amend and resubmit (often free of a second fee within 12 months in England) or appeal.

Do neighbours get consulted?

Yes for a full application: the council writes to them or puts up a site notice.

Are the drawings mine?

You can use them to get other quotes, subject to the terms.

Can planning conditions affect the build?

Yes, for example matching materials or obscure glazing. We plan for them.

Where