What is a pyramid roof?
A pyramid roof — also called a pavilion or tented roof — has four equal triangular slopes that meet at a single point. There is no ridge, only an apex. The plan is square or close to it; on a polygonal plan the same form appears with more facets, as on a spire or an octagonal summerhouse.
Difference from a hip roof
A hip roof also has four sloping planes, but it has a ridge: two trapezoidal and two triangular faces. Only when the ridge shrinks to nothing and the plan is square do you get a pyramid roof. Architecturally the difference is slight; structurally it is not, because in a pyramid roof all the hip rafters bear on one point and every force meets in that node.
Structure
- Hip rafters. From each corner of the plan a rafter rises diagonally to the apex. They form the skeleton and are the heaviest members of the roof.
- Apex connection. Where four or more hips meet, a robust joint is needed: a king post, a steel gusset plate, or a short reinforced apex block.
- Jack rafters. The planes between the hips are filled with progressively shorter rafters cut against the hip.
- Spread. A roof without a ridge beam pushes the walls outward. Tie beams, a ring beam or a sufficiently stiff wall plate must take that thrust; on a free-standing structure like a garden room or pavilion this is easily underestimated.
Applications
Towers and spires, church towers, dormers and bays, garden buildings, gazebos, pavilions, station buildings and detached villas on a square plan. The calm, symmetrical silhouette suits a building seen from every side.
Points to watch on site
- The apex is the leak point. Four or more hips meet at a sharp angle; tiles alone will not close that. Use a proprietary hip and apex system, a finial, or a lead or zinc cap. Never rely on mortar alone: it cracks.
- Ventilation of the roof plane. Without a ridge there is no continuous outlet; fit vent tiles or build ventilation into the apex piece, or moisture will stay trapped in the structure.
- Mark out carefully. Jack rafters against a hip need a compound cut (both bevel and angle). Make one as a template, check it, and only then cut the rest.
- More waste. Four triangular planes mean far more cutting of tiles or slates than a gable roof. Allow for extra material and labour.
Related terms
- Hip roof
- Gable roof
- Hip rafter
- King post
- Finial
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