Wraparound extension plans London: why they usually need planning permission

Worked example: why a full-width wraparound fails the half-width limit

This example is arithmetic, not a real job, and the dimensions are assumed. A mid-terrace Victorian house is 5.2 m wide at its widest point and has an original rear outrigger. Half the width of the original house is 2.6 m. The owner wants to fill the 1.5 m side return alongside the outrigger and extend 3 m across the whole back of the house, in one single storey extension.

The extension extends beyond a side wall of the original house, so A.1(j) applies. It also extends beyond a rear wall, and where the original house has a stepped back, the guidance measures the depth from each rear wall the extension goes beyond, so a long outrigger can also make the scheme fail on depth. The total width of the enlargement is 5.2 m, which is more than the 2.6 m maximum, so A.1(j)(iii) fails and the extension needs a planning application. The guidance gives the same result for any extension that goes beyond a side wall and is more than half the width of the original house.

A smaller scheme changes the route. If the total width of the extension stayed within 2.6 m, it was a single storey no higher than 4 m, and it went no more than 3 m beyond each rear wall it extends beyond, it could be permitted development, subject to the other Class A limits. A rear extension on a house with no side return or outrigger, built wholly behind the back wall, is judged by the rear limits alone. Which description fits depends on the shape of the original house, so the existing drawings must show the original walls.

What do councils test in a wraparound application?

Where the extension is outside permitted development, the council weighs the scheme against its adopted local plan and its residential design guidance. A wraparound meets the same questions as a side return and a rear extension at once: daylight and outlook for the neighbours either side, the height and bulk of the flank wall on the boundary, the amount of garden left, and the roof form seen from surrounding gardens.

Councils set their own daylight tests, and some use a 45 degree line from the neighbour's nearest window. It is local guidance, not part of the permitted development order, and the window and angle differ between boroughs. We read your borough's current guidance before the first sketch, and the section through the neighbour's window is where the test is shown.

Rooflights and a stepped or sloping roof at the boundary are the usual ways to keep the side element subordinate. The Class A condition A.3(a), materials of a similar appearance to the existing house, is a useful design starting point even when an application is needed.

What changes for a wraparound in a conservation area?

On article 2(3) land, which includes conservation areas, paragraph A.2 removes three things from Class A, and applies the side and storey limits to the total enlargement: cladding the exterior in stone, artificial stone, pebble dash, render, timber, plastic or tiles; any enlargement beyond a wall forming a side elevation; and any enlargement of more than one storey beyond the rear wall. The whole wraparound therefore needs a planning application, because its side element takes it outside Class A whatever its width. The 6 m and 8 m prior approval route is also unavailable on article 2(3) land (A.1(g)).

The council also judges the scheme against its duty to the area: the character set out in the conservation area appraisal, the street and garden views, materials and the effect on trees. Our conservation areas and Article 4 guide explains how to check whether your street is covered and whether an Article 4 direction removes further rights.

After consent: building regulations, structure and party walls

A wraparound takes out most of the old back wall, so the structural design carries the first floor and roof over a wide opening. The steel, its padstones and the foundations along the boundary belong in the building regulations set, which is prepared from the approved planning drawings. Our building regulations drawings page lists the set, and building control owes a decision on a full plans application within five weeks, or a longer period agreed in writing (regulation 14A(6)).

The Party Wall etc. Act 1996 is a separate regime and often applies twice to a wraparound. Section 1 covers a new wall built on the line of junction where the land is not built on there or has only a boundary wall that is not a party fence wall, with notice at least one month before work starts. Section 2 covers cutting into or raising an existing party structure or party fence wall, such as seating a steel, with a party structure notice at least two months before (section 3). Section 6 covers excavation within 3 m of a neighbouring building that goes deeper than its foundations, and within 6 m on the 45 degree test, with notice at least one month before. See our party wall surveying page.

How much do wraparound extension plans cost?

The price panel on this page shows the starting price for wraparound extension drawings, covering the measured survey, planning drawings with structural design and council submission. It is the total you pay, survey included. Council planning fees are separate and paid to the council. The pricing page lists the other extension options.