A wraparound combines a rear extension with a side return infill. Each half can be permitted development on its own, but combined they usually exceed the limits — so a wraparound is normally a full planning application, and the roofline is what decides it.
Last checked against current guidance on 2026-08-09. Rules differ by borough — the local pages below say how.
A single extension occupying both the rear projection and the side return of a terraced or semi-detached house, forming an L in plan.
It is the standard answer to the Victorian and Edwardian London terrace: a narrow original kitchen in the back addition, a dead side alley beside it, and a garden the house barely opens onto. Filling both at once produces the wide rear kitchen most people are actually after.
Because Class A treats rear and side extensions differently, and a wraparound has to satisfy both sets of conditions at once.
Most wraparounds fail at least one of these, so the honest advice is to plan for a full application rather than hope for a certificate.
Roofline and bulk at the boundary, far more often than floor area.
A wraparound has to resolve two roofs meeting at a corner — the rear projection's and the side return's. Schemes that leave that junction unresolved read as bulky, and it is the elevation, not the plan, that gets refused.
Build cost moves with your builder, your specification and the month you tender. What you can pin down early is the design and compliance scope — how many drawing sets the council and building control will want, and whether structural input is in play. The estimator below works that out from the project type and floor area.
Move the controls for an indicative figure. It anchors your budget — it is not a quote. Every project is priced after a free survey.
Build costs are separate and quoted by your contractor. See our published fees.
Start from the neighbour's constraints, not from the plan you want. Survey the adjoining rear addition's eaves and window positions, draw the 45-degree lines first, and design the roof inside them. Losing 200mm of ridge height on paper is far cheaper than losing eight weeks to a refusal.
Flat roofs with a set-down at the boundary and generous rooflights over the deep plan are the pattern most London boroughs accept: bulk stays low where the neighbour feels it, and the height sits in the middle of your own plot.
In floor-area terms a wraparound usually adds more than a straight rear extension of the same depth, because the side return is dead space that costs no garden. In programme terms it costs a planning application and, in a terrace, party wall procedures on both sides.
If the alternative is two separate projects a few years apart, doing it once is nearly always the better trade — the groundworks, the roof and the disruption happen once.
Rarely. Each part must independently satisfy its own Class A conditions and the combined footprint must stay within the 50% land coverage limit. Possible on a wide plot, but the exception.
Not for planning — they are consulted, not asked to consent. Under the Party Wall etc. Act 1996 you must serve notice, and they can dissent, which appoints surveyors.
Usually yes. Plan bin and bike storage at the front or through the house before you commit to the layout.
Councils aim to determine householder applications within eight weeks of validation. Complex or contested schemes can go to committee, which adds time.
Only where the new foundations go deeper than the neighbour's. The structural engineer decides that from the trial hole, not from the plan.
A wraparound is a side infill and a rear extension built as one, which is why it so often falls outside permitted development and into a full application. The side element is the usual culprit. Your borough's Local Plan and any residential extensions SPD set the local limits on top of the national ones:
