A house extension in Ealing is won or lost on the rear building line — how far the back of the house can push into the garden before the addition reads as an over-development of the plot. Ealing's Edwardian semis and double-fronted villas often sit on generous suburban gardens, which tempts an ambitious footprint, but the useful question is the defensible depth: how far a full-width single-storey rear can project before it overshadows an attached neighbour's windows, erodes the garden that remains or breaks the pattern of rear elevations along the street. We model the projection in section against the neighbouring boundary and the daylight reaching adjoining windows, then set a depth that is both liveable and supportable at planning.
The choice between a single and a two-storey addition changes the assessment entirely. A single-storey rear across the full width is judged largely on garden impact and neighbour daylight, and on how the new back wall and roof meet the original elevation. A two-storey extension — realistic on many of Ealing's wider semi and villa plots — brings first-floor outlook, overlooking and a sense of enclosure over a neighbour's garden into play, and is far more sensitive on a semi-detached pair where the two houses share a boundary. We advise early which storey height a given house and plot can carry, because that decision governs both the design and the planning route.
The two-storey side extension is where Ealing's wider plots genuinely differ from inner London. On a semi-detached house or a double-fronted villa the flank often has room for a full two-storey addition beside the original house, but the constraints are exacting: the council resists a side extension that reads as a mirror-image doubling of the house or that closes the gap between buildings that gives the street its grain. We typically set the side addition back from the front building line and down from the ridge, keep a visible separation from the neighbour where the plot allows, and detail it as subordinate to the host — the moves that keep a large addition legible as an extension rather than a second house.
Structure and neighbour boundaries run alongside the design. A full-width rear removes most of the original back wall, so the load above is carried on a beam sized by a structural engineer, and a two-storey side addition needs its own foundations designed against the ground and the existing house. On Ealing's semis and terraces those foundations and beams frequently sit within three or six metres of a neighbour's structure, or on the line of junction with an attached house, which engages the Party Wall etc. Act 1996. Those notices are separate from the planning decision and are best programmed early, so we identify the notifiable neighbours at design stage and coordinate with a party wall surveyor.
Daylight and the neighbour relationship deserve attention before the footprint is fixed rather than after. Ealing's houses, though more generously spaced than inner-London terraces, still sit close enough for a full-width or two-storey addition to affect an attached or adjoining neighbour, and the council assesses daylight and sunlight to neighbouring windows using the established BRE tests. A well-judged section — controlling height near the boundary, stepping a roof down and holding a two-storey element back from the shared wall — usually keeps a scheme within them. Right to light is a separate civil matter that planning consent does not resolve, so where an extension approaches a neighbour's window we flag it early so it can be addressed rather than discovered late.
From there the route is a coordinated one. We survey the house, test the extension against the council's massing and daylight constraints and confirm the conservation position for the address, then develop a design that an Ealing case officer can support before producing the planning drawings and, once the principle is settled, the building regulations package for construction. Building regulations cover the new structure, fire, insulation, ventilation and drainage, and on a full-width rear the diversion of the existing drainage across the new footprint has to be resolved on the drawings. The result is an extension that adds real family space without unbalancing the house, its neighbours or its garden setting.
