A Shepherd’s Bush side return is the narrow strip of open ground — often little more than a metre to a metre and a half wide — that runs alongside the original two-storey back addition of a Victorian terrace. On the bay-fronted and flat-fronted terraces that fill the streets around the Green and off Askew Road and Goldhawk Road, that alley is largely dead space: it lights a side window or two, carries a downpipe and a drain, and adds almost nothing to the plan. Infilling it squares off the rear of the house and turns a cramped, single-aspect galley kitchen into a room the full width of the plot, usually opening onto the garden. The footprint added is small, but the gain in daylight and usable area is out of all proportion to it, which is why the side return is the most requested project on these terraces. Because the alley is so narrow and enclosed, the gain is almost entirely internal — the street elevation and the front of the house are untouched, so the project reads as an inside transformation rather than a visible external change.
The defining constraint is the flank boundary the side return is built against. On a terrace the alley sits hard against the neighbour’s land, so the new flank wall is almost always raised either on or tight up to that boundary line — which brings the Party Wall etc. Act 1996 into play from the first course. Building on the line of junction, and excavating for the new foundation within three or six metres of the neighbour’s structure, are both notifiable events that run entirely separately from the planning decision. The neighbour on that side is the closest and most affected party, so we identify them and prepare notices early, and we design the foundation so it can be formed without trespassing onto their ground — an eccentric or reinforced footing where a traditional spread foundation would overhang the line.
Drainage is the detail that side-return schemes live or die on, and it is what most distinguishes this project from a plain rear extension. That side passage is typically where the original rainwater downpipes, the back-addition gully and often a shared foul drain or an inspection chamber all run. Once the alley is roofed and floored they cannot simply be buried: surface water must be collected and re-routed, any drain that ends up inside the new footprint may need diverting or building over with the water authority’s agreement, and an inspection chamber left within the extension needs sealed, double-cover access. We survey the below-ground drainage before the layout is fixed, because a gully or a manhole in the wrong place can move a wall, dictate the floor build-up, or force a build-over agreement that adds weeks to the programme.
Roofing the infill is a geometry problem specific to the side return. The strip is narrow and boxed in — the two-storey flank wall of the back addition on one side, the neighbour’s boundary on the other, and the back-addition’s own roof rising above it. The new roof therefore usually runs as a lean-to or a flat roof tucked against those walls, meeting the existing back-addition roof at a valley or a weathered abutment. Threading a glazed roof, a run of rooflights or a lantern into that strip is what pulls daylight deep into the widened kitchen, but the flashings, the valley gutter and the upstand against the neighbour’s wall are exactly where leaks begin if they are detailed loosely. We resolve those junctions on the drawings, with defined falls and lead details, rather than leaving them to be improvised on site against old, uneven brickwork.
On planning, a single-storey side infill on a house can in principle proceed under permitted development, but Shepherd’s Bush is threaded with conservation areas — the council names the Wells and Askew areas among several across the neighbourhood — where Article 4 directions frequently withdraw those rights. Where your terrace sits inside one of them, even a modest side return needs a full householder application to Hammersmith & Fulham, determined in around eight weeks once validated. Flats carry no permitted development at all, and many houses on these streets have been split into upper and lower flats, so freeholder consent and the leaseholders’ positions can matter as much as the planning route. We confirm the conservation designation and the tenure for your exact address before assuming any particular path, because getting that wrong wastes the most time.
From there the process is deliberately ordered. We measure the back addition, the alley width and the drainage, test how much the infill can capture against the daylight reaching neighbours on these tightly packed plots, and settle the flank wall and the roof form before any drawings are issued. The planning submission carries the design and, where the address falls in a conservation area, a short justification of the materials and the effect on the rear townscape. The building regulations package then covers the foundation near the boundary, the new roof’s insulation and weathering, the drainage diversion and the structural beam needed where the old flank wall between the kitchen and the alley is removed. Party wall notices run in parallel, so the build is not held up once consent lands.
