What is a metal roof hip cap, and how is it installed?
Short answer. A metal hip cap is the formed trim that covers the hip, the sloped outside corner where two roof planes meet, sealing the joint between the angled panel cuts. It installs much like a ridge cap, over closures and sealant, but runs from the eave up to the ridge so each piece laps over the one below it.
How a hip differs from a ridge
- Direction: hip caps start at the eave and work upward, so each upper piece laps over the lower one and water runs over the laps.
- Angled cuts: panels meet a hip at an angle, so their edges are cut diagonally. The cap needs enough width to cover irregular cuts.
- Closures: profile-matched closures do not fit diagonal cuts well, so installers often use universal foam closures cut to fit, or Z-closures on standing seam, bedded in sealant.
- Two ends to finish: the bottom end is closed at the eave, usually by notching and folding, and the top end tucks under the ridge cap where hip meets ridge.
Installation outline
- Cut and install the panels on both sides of the hip, leaving the cut edges neat and fastened.
- Seal and install closures along each side.
- Set the first cap piece at the eave and finish its bottom end.
- Fasten through the cap into the panel high points or closures per the manufacturer.
- Lap each next piece over the last with sealant.
- Finish at the top so the ridge cap overlaps the hip cap.
Where hips leak
The hip to ridge intersection, the open bottom end at the eave, gaps under the cap where panel cuts wander, and fasteners placed in low spots where water runs. On older exposed fastener roofs, dried-out washers along the hip are common leak points too.