Hip-to-Gable Loft Conversions

1. 1

   The hipped side of the roof is removed: the sloping side roof, including the hip rafters, is taken down.

2. 2

   A new gable wall is built: the side wall of the house is built up vertically to the height of the ridge, usually in brick or blockwork finished to match the house.

3. 3

   The roof is extended: the ridge is carried across to the new gable, and new rafters and roof tiles complete the roof.

4. 4

   The loft is converted: a new floor, staircase, insulation and windows turn the space into a room, often with a rear dormer added at the same time.

A structural engineer checks that the existing side wall and its foundations can carry the new gable, and designs any steel beams needed.

• Semi-detached houses: The most common type. The hipped side is built up to a gable, while the party wall side stays as it is.
• End-of-terrace houses: The same approach as a semi, on the exposed end of the terrace.
• Detached houses: Both sides can be converted, known as a double hip-to-gable, where the roof and planning allow.
• Bungalows: A hip-to-gable conversion can turn a hipped bungalow roof into usable upstairs rooms.

A hip-to-gable conversion only works on a hipped roof. Houses that already have a gable roof, such as most mid-terraces, usually suit a dormer loft conversion or an L-shaped loft conversion instead.

On its own, a hip-to-gable conversion enlarges the loft, but the rear roof slope still limits head height. Adding a rear dormer at the same time creates vertical walls at the back and the side, so most of the loft floor has full standing height. It is the usual choice for families who want a large bedroom with an en-suite, or two rooms, in the loft. Both parts count together towards the permitted development volume allowance, so the design has to balance the two.

One of the biggest benefits of a hip-to-gable conversion is the staircase. On many semis the existing stairs run up the side of the house, directly under the hipped roof, where there is not enough headroom for a new flight into the loft. Building the side up into a gable creates the height needed, so the new staircase can continue straight up above the existing one. It saves space on the floor below and gives a natural route into the loft.

Often not. A hip-to-gable conversion on a house in England is usually permitted development if:

• Volume: All roof additions, including any rear dormer, stay within 50 cubic metres for detached and semi-detached houses, or 40 cubic metres for terraced houses, including end-of-terrace.
• Height: Nothing is higher than the highest part of the existing roof.
• Front roof slope: Nothing extends beyond the roof slope at the front of the house facing the road.
• Materials: The new gable and roof look similar to the existing house.
• Side windows: Any side-facing windows are obscure-glazed and non-opening below 1.7 metres.

Planning permission is needed for flats and maisonettes, listed buildings, many conservation areas and where an Article 4 direction applies. Corner plots, where the side of the house faces a road, should be checked carefully. We confirm the position at the survey and can apply for a Lawful Development Certificate.

On a semi-detached or end-of-terrace house, the new roof structure and steel beams often bear onto or into the party wall. That needs a notice under the Party Wall etc. Act 1996 before work starts. The conversion also needs building regulations approval for:

• the structure of the gable, roof and floor
• a protected escape route and interlinked smoke alarms
• the staircase
• insulation
• ventilation

We arrange the inspections and hand you the completion certificate.

The new gable is the most visible part of the conversion, so matching it to the house matters. Where the house is brick, we source bricks as close as possible to the existing ones. Rendered houses are rendered to match. The roof is completed in matching tiles. On semi-detached houses, the neighbour's side will keep its hipped roof unless they convert too. We can talk you through how the finished house will look at the survey.