The right conversion depends on the roof you start with. Many of Ealing's Edwardian bay-fronted semis carry a hipped roof on the outer side, where a hip-to-gable move squares off that slope and unlocks genuine floor area, usually paired with a rear dormer set into the back slope. On a mid-terrace house there is no hip to gable, so the useful room comes from a rear dormer alone, with rooflights to the front slope. The double-fronted Victorian villas often have steep, chimneyed roofs that convert well, though the chimney stacks and their flues have to be kept, relined or carefully removed with building control's agreement; the 1930s suburban semis tend to be shallower-pitched and give less. We match the option to your particular roof rather than to a template.
Whether the loft is worth doing usually comes down to head height. As a rule of thumb you want around 2.2 to 2.4 metres under the existing ridge before the new floor build-up, and the finished room has to hold that height across enough of its footprint to be usable once the sloping ceilings and the eaves cut into it. Ealing's steep-pitched Edwardian and Victorian roofs often clear that comfortably; the shallower 1930s and later roofs can leave full standing height only down the centre and awkward, low space under the eaves fit for storage rather than living. We measure the ridge, the pitch and the existing ceiling joists at feasibility, because that survey decides whether you gain a proper room or a compromised one.
The new staircase is the part owners most often underestimate. It has to rise from the floor below within the going and rise limits of Approved Document K and land with full headroom over the top, and it almost always consumes part of a bedroom or the landing on the storey beneath. On a bay-fronted semi the natural place for the flight is over the existing stair, continuing the same run up to the roof, but the position and the head height it needs frequently reshape the room below and can cost you a chunk of a first-floor bedroom. We resolve the stair at feasibility, model it in section against the new ridge and the dormer ceiling, because it governs both the cost to the floor below and whether the roof space is genuinely worth converting.
Fire escape is the requirement that catches people out. Turning a two-storey Ealing house into three storeys lifts the top floor above the 4.5-metre threshold measured to the new floor and triggers a higher standard: a protected stair enclosure running all the way down to a final exit, fire-rated doors — typically FD30 — to the habitable rooms off it, and mains-powered, interlinked smoke alarms on every storey. Where a period house has been opened up over the years — a knocked-through hall or a through-lounge — and the stair no longer sits in an enclosure, an alternative such as a sprinkler or mist system, or a compliant secondary escape, is designed in to keep the rest of the layout. We build the escape strategy into the drawings from the outset rather than letting building control reshape the layout late.
A converted roof needs new structure. Typically that means steel beams spanning the house and bearing onto the existing walls, with alterations to the ridge, purlins and rafters that a structural engineer designs and calculates so the roof can carry a floor rather than just its own weight. On the terraces and the semi-detached pairs those beams usually bear into the party walls shared with the neighbours, which engages the Party Wall etc. Act 1996, so notices go either side before work starts and the bearing pads are agreed. The roof is also where insulation is upgraded to current standards, and on a solid-walled period house that has to be detailed carefully at the eaves and dormer cheeks to avoid cold bridging, condensation and lost head height.
In a conservation street the deciding question is how the new roof reads against its neighbours. A rear dormer is generally kept subordinate — set down from the ridge, held in from the sides and party walls, its cheeks clad in lead, zinc or slate and its face glazed to a proportion that echoes the windows below. A hip-to-gable change alters the roof's outline seen from the side, so on a semi-detached pair it is judged against the matching half next door, and an unmatched gable on one half is a common reason a scheme is resisted. Front-facing roof changes are resisted, and in the Brentham Garden Suburb the Article 4 direction means even a modest alteration needs consent. We design the roofscape to the specific street, then set out the case in the drawings and supporting statement.
