Roof shapes are the various geometric forms in which a building’s roof can be built. The choice of roof shape influences appearance, structure, drainage, usable loft area and cost. In British and European construction dozens of variants exist, often combinations of a few main shapes.
Group 1: flat roofs
- Flat roof — nearly horizontal surface with at least 1.7% fall, finished with bitumen, EPDM or single-ply membrane
- Sawtooth roof — repeating sawtooths, mainly in industrial buildings for north-light
- Low-pitch mono-pitch — transition between flat and pitched
Group 2: simple pitched roofs
- Mono-pitch (lean-to) — one sloped surface, simple and cost-effective
- Gable / saddle roof — two slopes with central ridge, classic house form
- Mansard roof — two pitches per side, steep below and shallow above, providing more loft headroom
Group 3: multi-faceted pitched roofs
- Hipped roof — four slopes (two long, two shorter triangular ones), no gable wall
- Pyramid (tent) roof — four triangular slopes meeting at a single point, common on square towers
- Half-hipped roof (jerkinhead) — gable roof with a small hip at the top
- Cross-gable roof — two gables intersecting at right angles, often above a cross-shaped plan
Group 4: special roof shapes
- Barrel-vault roof — curved roof surface, mainly in industrial buildings and modern architecture
- Inverted (butterfly) roof — V-shaped roof with a central valley
- Shell roof — thin curved roof of reinforced concrete or steel
- Air-supported roof — tensioned fabric or membrane over a light structure
- Green roof — flat or gently sloping roof with planted substrate
Choosing a roof shape
Selection involves:
- Local planning policy — local authorities often prescribe roof shapes
- Design committee — judges whether the form suits the surroundings
- Usable space — a mansard roof offers more headroom than a pyramid roof
- Structure — symmetrical shapes are simpler to build
- Energy performance and solar potential — a well-oriented pitched roof suits PV panels
Application
In practice, combinations are common: a main volume with a gable roof, a flat-roof extension and a dormer with a mono-pitch. It is standard to fix the roof shape during the sketch design, because it determines so much of the overall structure.
Related terms
- Roof shape
- Gable roof
- Hipped roof
- Flat roof
- Mansard roof
- Mono-pitch
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