Hip

Hip geometry with commons mid-run, step-down flat-top trusses in the hip zones, a king common at each ridge end, jack rafters on both the side and end planes, and eave assemblies wrapping all four walls. The ridge runs length minus width; roof panels cover four planes with diagonal cuts.

Also called: hipped roof · four sided roof · no gable ends · hip set

1. 1Hip rafters run the whole plan diagonal, tail included, because the hip carries the corner of the overhang where the two fascias meet.
2. 2Side-plane and end-plane jack rafters run from each eave to the hip so the corner purlins have something to land on.
3. 3A king common at each hip end gives the four hip rafters a member to die into (IRC R802.3 — a hip must land on a member, not on air).
4. 4All four fascias are cut as ONE mitered plan-profile frame: full length on the outer face, one board thickness shorter on the inner, so the four miters share the same diagonals and the frame closes with zero gap and zero overlap.
5. 5Hip caps are mitered to a point at the eave corner and stop short of the ridge cap, which laps over where they converge.
6. 6Rails: 3/12 minimum (below that hips act as beams and need engineering), 70ft span ceiling, and the plan must be at least as long as it is wide.

• ◆Hip corners that cannot close with axis-aligned trim.
• ◆Purlins and jacks framed over open air in the hip zones.
• ◆Low-slope hips quoted as a rafter system when they are a beam design.