A leak on a hip roof usually shows up in the attic at the spot where two slopes come together, not in the middle of a slope and not at the ridge where many people look first. A hip roof has four slopes that meet along diagonal lines called hips, and each hip is a seam where water runs down one plane and has to pass onto the next. The seam is only as good as its cap, its underlayment, and the shingles cut to meet it. When any of those fails, water travels along the seam for a few feet before it finds a gap, so the stain on the ceiling can sit well away from the place where the water entered.
This page is for a St. Louis homeowner who has a stain, a drip, or a damp smell on the top floor and wants to know whether the repair will be small. A hip leak is often small once it is found, but it is rarely found from the ceiling alone. The work is in tracing the path the water took, then deciding whether one cap, one run of shingles, or the underlayment under a whole hip needs attention. Keys Roofing can be reached at (314) 220-2333 if you want the roof walked and documented before you decide.
Why the hip is hard to read from the ground
From the street, a hip roof looks uniform. The four slopes share the same shingle, the same color, and usually the same age, so a patch of older shingles is hard to see unless the light is low. The hip caps are the shingles folded over the diagonal lines, and each one is cut and fastened individually. A missed nail or a lifted corner on one cap can look identical to a sound one from the yard. Much of the water entry on a hip happens under the caps, not on the open field of the slope.
Inside, the attic tells a different story. The rafters on a hip roof do not run straight from eave to ridge. The hip rafter runs diagonally, and the jack rafters that meet it shorten as they approach the corner. Water that runs down a hip often follows the hip rafter or the sheathing joint beneath it, so the wet wood can show up several feet from the corner. That is why a stain on a ceiling near the north wall may have started on the west hip.
Where water gets in on a hip
There are three common entry points. The first is the hip cap itself. Caps are fastened through the shingle face, and the nail heads are the weak point. Sun and freeze thaw cycles lift the cap tabs over time. In St. Louis, the swing from January freezes to spring rains can lift a cap enough that wind-driven rain gets under it on the next front.
The second is the underlayment under the hip. Older hip roofs were often built with the underlayment run up from the eave and lapped over the hip with little overlap, so water that gets past the cap has a direct path onto the deck. If the underlayment has torn at a nail or split along the hip line, the deck absorbs water and the attic side turns dark.
The third is the place where a hip meets a valley or a dormer. A hip that runs into a valley is a junction of three planes, and it is a spot that is hard to seal correctly. Water running down the valley can back up at the hip if the shingles were not woven or cut tight. If the leak appears only during storms that push water up the slope, check this junction first.
What to look for before you call anyone
- Stains on the attic rafters or sheathing that run diagonally, toward a corner of the house.
- Dark streaks on the underside of the deck near a hip rafter, even where the ceiling below is dry.
- Hip caps that sit high on one side, or caps with fasteners that have backed out and lifted the tab.
- Granule loss on the caps, which is common on older hip caps because they take more sun than the field.
- Rust or corrosion on metal flashing where a hip meets a wall or a chimney.
Take dated photographs of each, and note whether the leak happens in wind-driven rain, steady rain, or only after the roof has been wet for an hour or more. Those observations help the person tracing the leak. They also give you a record if the problem returns.
What the repair usually involves
A tight hip repair is rarely a bead of sealant. It means lifting the caps along the affected hip, checking the underlayment beneath, replacing any torn or damaged sections, reinstalling the caps with proper fasteners, and then checking the shingle courses on both adjacent slopes to make sure the cut lines are tight. If the sheathing has softened, the wood has to be replaced before the underlayment goes back. Those steps add time, but they address the cause instead of the stain.
Replacement shingles should match the existing roof where possible. Keys installs Atlas and Malarkey shingles, and a repair crew will check the cap profile and exposure before cutting new pieces. If the existing caps are a product that no longer matches, ask for that in writing and ask how the mismatch will be handled. Two caps of slightly different color on the same hip are a cosmetic issue, but a cap with the wrong exposure can channel water instead of shedding it.
What to ask
- Which hip or hips are involved, and how did the crew determine that?
- Will the caps be lifted and reset, or only sealed on top?
- What happens to the underlayment at the hip line, and will the crew show it to you before it is covered?
- If sheathing is soft, is replacement included in the price, or is it a separate line?
- Will the crew provide photographs and measurements of the repair in writing?
Keys documents what it finds and puts a written scope with photos and measurements in your hands. If an insurance claim is involved, Keys attends as the contractor while you deal with your own insurer. Missouri law (RSMo 407.725) bars a roofing contractor from representing or negotiating a homeowner's insurance claim, and from saying anything about paying, waiving or covering a deductible, so those conversations stay between you and your insurer.
When a hip repair is not enough
If the sheathing is soft across several feet, if the underlayment is brittle along the whole hip, or if the hip caps are the original product and the field shingles have reached the point where they cannot be repaired without visible patching, the decision may shift toward replacing that section or the full roof. Ask the crew to show you the condition of the deck at the cut, not just the surface. A repair that looks complete from the ground can still leave a hip that leaks again within a season.