Glossary
Hip-to-gable conversions on a London semi or end terrace
Squaring off a sloped (hipped) side wall to create vertical (gable) wall. Used to expand loft space.
Squaring off a sloped (hipped) side wall to create vertical (gable) wall. Used to expand loft space.
A hip-to-gable conversion squares off a sloping hipped roof end into a vertical gable wall, adding the volume a loft conversion needs. It is the standard first move on a 1930s semi-detached or end-of-terrace house, and it is normally combined with a rear dormer within the same 50 m³ permitted development allowance.
Any house with a hipped roof slope at one or both ends — overwhelmingly inter-war semis and end-of-terrace houses, and detached houses of the same period. A mid-terrace house has no hip to convert, so it goes straight to a rear dormer.
The gain is substantial: squaring off the hip typically adds 15 to 20 m³ before the dormer is counted, and it moves the usable floor area outward to the flank wall so a staircase can land sensibly.
Usually, on a semi or detached house, within the 50 m³ allowance and provided the extension does not exceed the highest part of the existing roof, does not extend beyond the plane of any roof slope fronting a highway, and uses similar materials. Rights are withdrawn in conservation areas and National Landscapes, and on flats.
A double hip-to-gable on a detached house consumes the allowance quickly, so the volume calculation is done before the design, not after.
The new gable is built off the existing flank wall, which needs checking for its ability to take the load, and a new ridge beam or purlin arrangement spans to it. On an end-of-terrace the party wall is engaged, so a party structure notice with one month's notice is normally served.
How hip-to-gable loft conversion plays out in Hackney: London Borough of Hackney (Hackney Council) maintains 29 conservation areas, the De Beauvoir Town Conservation Area and the Stoke Newington Conservation Area among them, and an Article 4 direction is in force there, so permitted development cannot be assumed. Anyone dealing with hip-to-gable loft conversion at a Hackney address is therefore working to a £548 householder application decided in 8 weeks, or a £249 prior approval over 6 weeks where hip-to-gable loft conversion still qualifies.
| Typical volume added | 15–20 m³ before the dormer |
|---|---|
| Allowance, semi or detached | 50 m³ |
| Allowance, terrace | 40 m³ |
| Best suited to | Inter-war semis and end-of-terrace houses |
| Party structure notice | One month |
| Our loft package from |
No. There is no hipped end to square off; a rear dormer is the route.
Yes, cumulatively with any dormer and any previous roof extension.
On an end-of-terrace or semi, normally yes, because the gable bears on the party wall.
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