Wraparound extension drawings in Merton

Which Merton guidance applies to a wraparound

Unlike some neighbouring boroughs, Merton's design guidance gives no dimensioned rule specific to a wraparound that we can cite. The documents an officer will lean on are the Borough Character Study SPD, which asks new work to respond to the character of its street, and the Small sites toolkit SPD. The local plan was adopted in 2,024, and its design policies sit behind both.

Without a published number, the argument has to be built from the drawings: the proposed wings read as one composed addition, materials relate to the house, the side wall is set back from the front, and the roof form is simple enough not to compete with the original. We present those points as annotated elevations so the case officer can see them at once.

Roof form deserves the most thought. A wraparound often ends up with a flat or lantern-lit roof over the infill, a pitched roof over the old outrigger and a different pitch again at the side, and three roof types on one extension looks unresolved from the neighbours' windows. We usually test two roof options on the elevations and recommend the simpler one, because it is cheaper to build and easier to defend.

Be aware too of the Basement and subterranean SPD. It is aimed at basements, but a deep foundation or a lower-ground element in a wraparound can bring it into play.

Prior approval statistics for Merton

National rules define the rear element as: 3 m (attached) / 4 m (detached) beyond the original rear wall, single storey, and the side element as: Side extension: single storey, max 4 m high, max half the width of the original house. The larger-home prior approval lets the rear go deeper. In the latest national figures the council granted 22 of these notifications and refused 80.

Refusals far outnumber approvals, so we tell clients to speak to the adjoining owners before choosing the route, and to treat a householder application as the safer path for a deep wraparound.

Merton householder decisions

Merton decided 759 householder applications in its latest published year, granted 92.9 per cent and decided 85.2 per cent within eight weeks or an agreed extension. Those figures cover every householder scheme, most of them modest, so they say little about a wraparound in particular.

Gardens occupy 27.2 per cent of the borough's land. A wraparound is the extension that takes the most of a garden, so the proposed plan states the retained garden depth and area beside the footprint.

Wraparound extension drawings in Merton: what you receive

You get existing and proposed floor plans, sections, elevations, a location plan and a block plan, all checked by a second chartered technologist. The price is £1,195 including VAT, fixed in advance, and we redraw at no extra cost if the council requests changes before it decides. Merton's own application fee is £548.

Where the new wall sits on or near the boundary, the neighbour needs notice. The rule is: Line-of-junction (new wall) notice at least 1 month before work. Digging beside a neighbour's footings is covered separately: Adjacent excavation notice at least 1 month before work: within 3 m and deeper than the neighbour's foundations, or within 6 m and cutting a 45° line from their foundations. A surveyor appointed for the notices will want to see the same set of drawings, so we draw them to serve both purposes.

Next steps and nearby boroughs

A single-element scheme may fit better: rear extension drawings in Merton and house extension drawings in Merton are the alternatives. Adding a bedroom above is covered by loft conversion drawings in Merton. See also architectural drawings in Merton. Neighbouring Sutton and Wandsworth have their own rules.