Wraparound extension: design, planning and cost factors

What makes a wraparound different

Because it wraps around a corner of the house, a wraparound extension creates a new corner of its own. That corner is the key structural and design detail: the roofs meet, and the existing back and side walls are often both opened up. The layout gains width and depth together, which is why it is popular for open-plan kitchens.

Layout and glazing

The L shape lets you zone the space, for example cooking along the side and living at the rear. Rooflights over the side section bring light into the middle of the house, and large doors on the rear open onto the garden. Thinking about where furniture, the kitchen and storage go early helps avoid wasted corners.

Roof options

Flat roofs with rooflights keep height down near boundaries. Pitched or partly glazed roofs can look better against the house but need careful detailing where the two roofs meet. The roof choice also affects internal ceiling height and drainage.

Our flat vs pitched extension roof guide compares the options.

Planning permission

Rear and side extensions each have their own permitted development limits, and wraparound designs often go beyond what those allow combined, so many need a planning application. Councils look at the effect on neighbours, the height near boundaries and how the side element relates to the street. Building regulations approval is always needed, and party wall procedures are common.

Wraparound extension cost factors

The main cost drivers are size, foundations along two elevations, the steelwork needed to open up the corner of the existing house, the roof design, glazing and the kitchen fit-out. Work inside the existing house, such as relocating a kitchen or removing walls, adds to the scope.

• Floor area and foundation length
• Steel beams and corner posts
• Roof type and rooflights
• Glazing and doors
• Kitchen and internal alterations

Is a wraparound right for you?

If the side return is narrow or the garden is short, a simpler rear extension may give most of the benefit with less structure. If you want a single large space with light from two sides, a wraparound is often the answer.

To discuss a design, see our extensions service.

Living through the build

A wraparound extension usually involves opening the rear and side of the house, often where the existing kitchen is. Many families set up a temporary kitchen elsewhere while the back of the house is opened up and the new structure is installed. The new and existing parts are usually kept separated with temporary screens until the extension is weathertight. Asking how the programme will be sequenced, when services will be disconnected and how dust is controlled helps you plan whether to stay at home during the noisiest phases. Agreeing access routes through the side of the house or garden for materials and waste is also worth doing early, especially where the side return is the only route to the rear.

Neighbours and boundaries

The side section of a wraparound often runs close to or along a boundary, so the height, roof shape and any windows facing the neighbour need care. Talking to neighbours before an application is submitted can head off objections. Where foundations come within certain distances of a neighbour's building or the wall sits on the boundary, party wall notices are usually needed.

Common questions