Hip to Gable Loft Conversions: Is It Right for Your Home?

Walk a street of 1930s semis and you will see the two roof shapes that decide loft conversions. Some houses end in a flat vertical gable wall; others end in a hip, a third slope leaning in from the side. The hip looks gentle and costs you the loft: it slices the headroom away exactly where a staircase and a bedroom want to be. A hip to gable conversion rebuilds that slope as a full gable wall, and suddenly the loft is a floor.

Hip to gable is the natural move for semi-detached and end of terrace houses with hipped roofs, the classic interwar London stock, and for detached houses it can be done both sides at once for maximum volume. Mid-terrace houses rarely need it, because they already have party walls where the hips would be. If your loft currently offers standing room only at the ridge, this is usually the conversion type that changes everything, because it adds volume exactly where the staircase needs to land.

On its own, a new gable buys headroom at the side. Paired with a full-width rear dormer, it transforms the whole storey: the gable gives the stair its height, the dormer gives the rooms their width, and together they typically yield a double bedroom with en suite where a crawl space used to be. This pairing is the workhorse of London loft conversions on hipped-roof houses.

Many hip to gable conversions proceed under permitted development, within the volume allowances of 40 cubic metres for terraced houses and 50 for semi-detached and detached, with the usual conditions on materials and roof plane. Two cautions decide the exceptions: permitted development rights do not apply in conservation areas and can be removed by local conditions, and the volume maths must include everything you are adding, gable and dormer together. We check the specific house before promising the easy route, because the easy route is only easy when it genuinely applies.

We do not yet publish a hip to gable figure from our estimator. For scale, rear dormer loft conversions priced on our estimator in September 2026 came to 80,000 to 95,000 pounds ex VAT, indicative: around 82,000 pounds for about 20 square metres of new loft floor at a high specification, and around 92,000 pounds for about 28 square metres at a standard specification, each including a new stair, with windows, rooflights, sanitaryware and tiles priced for fitting only. A hip to gable with rear dormer involves more structural work than a dormer alone, so expect it to price above a comparable dormer conversion. For your own house and postcode, The Estimator will give you a realistic range in minutes.

Three early questions filter most surprises. Head height at the ridge now: around 2.2 metres or more and a conversion usually works. The neighbour question: on a semi, your new gable stands at the boundary, so party wall notices and a courteous conversation belong early in the plan. And the stair: the best conversions spend design time on where the staircase lands before falling in love with the bedroom layout. We design and build hip to gable conversions as one team, structure to finish; if your hipped roof is the only thing between you and another floor, talk to us.