A hip is the outward-projecting angle formed where two adjacent sloping roof planes meet at an external corner of a building. Unlike the horizontal ridge, a hip slopes, running from the corner of the eaves up to the ridge or to the apex of the roof. Roofs with hips on all corners are called hip (or hipped) roofs. The inward-facing equivalent, where two slopes meet at an internal corner, is a valley.
Framing
In stick-framed roofs, a hip rafter runs diagonally along the line of the hip, from the wall-plate corner to the ridge. Because it is longer than the common rafters and set at a lower pitch, it is cut with compound angles. Shortened jack rafters run from the wall plate up to the hip rafter. In medieval and traditional British carpentry, the foot of the hip rafter often sits on a dragon beam that projects diagonally from the corner. Truss roofs form hips using a set of stepped hip trusses or girder trusses with jack trusses.
Covering the hip
Hips are capped much like ridges:
- Hip tiles in clay or concrete, fixed over the joint and secured at the bottom with a hip iron in UK tradition. Bonnet hip tiles and bonnet-shaped plain tiles are traditional alternatives.
- Hip cap shingles on asphalt roofs, installed from the bottom up so each overlaps the one below.
- Formed metal hip caps on metal roofs.
- Mitred or close-cut hips in slate, with concealed soakers beneath.
Performance
Because water runs away from a hip rather than toward it, hips are less vulnerable to leaks than valleys, though wind uplift on hip tiles is a concern. Hipped roofs in general perform better in high winds than gable-ended roofs.