· by Michael Blair, Nashville's Roofers
A leak in the open field of a roof is rare. Almost every leak enters where the roof stops being a plane — a chimney, a valley, a vent, a wall junction — because that is where it depends on flashing rather than on shingles.
The usual suspects, in order
Chimney flashing is first, particularly step flashing that was surface-sealed rather than let into the mortar. Sealant fails in a few Nashville summers; properly counter-flashed metal does not.
Then pipe boots, where the rubber collar around a plumbing vent cracks after eight to twelve years of UV. Then valleys, then wall-to-roof junctions, then skylights.
- Chimney step and counter flashing
- Plumbing vent pipe boots
- Valleys, especially where debris collects
- Roof-to-wall junctions and dormer sides
- Skylight curbs and head flashing
Why the stain is not above the leak
Water entering at a penetration runs down the decking or along a rafter until it finds something to drip from. A ceiling stain can be several feet from the entry point and on the other side of a joist.
That is why chasing a stain from inside rarely works, and why a roofer who goes straight to the nearest penetration uphill of the stain is doing the right thing rather than guessing.
The leaks that are not the roof
Condensation in an under-ventilated attic looks exactly like a roof leak and appears in winter rather than during rain. Nashville humidity makes this common in houses with blocked soffit vents.
Gutter overflow is the other one. A blocked gutter backs water up under the shingle edge, which soaks the fascia and the wall and reads as a roof failure. It appears only in heavy rain and stops when the gutter is cleared.
What a competent repair looks like
Flashing replaced rather than sealed. Roofing cement smeared over a failing joint is a six-month fix that traps water behind it and rots the deck faster than the leak did.
Pipe boots replaced with the collar tucked correctly under the course above, not caulked over the top. If a quote consists mainly of sealant, it is buying you a season.