Do ridge vents leak, and why is my ridge vent leaking?
Short answer. A properly installed, baffled ridge vent rarely leaks, but ridge vents can leak when wind driven rain blows through an unbaffled vent, the slot is cut too wide or too close to the ends, nails are too short, cap shingles crack or blow off, or a power fan pulls rain in through the vent. Most of these leaks are fixable without giving up ridge venting.
The common causes
- No external baffle. Older roll vents and exposed aluminum vents let horizontal rain from strong storms blow straight in.
- Slot cut wrong. Too wide, or run all the way to the gable end, chimney, or a wall, so water has a direct path in.
- Short or overdriven nails. Nails that do not reach far enough into the deck let the vent lift. Overdriven nails crush the vent and break the cap shingle seal.
- Cracked or missing caps. Hail and wind damage the cap shingles first because the ridge is the most exposed part of the roof.
- Power fan or other exhaust. Suction from a fan can pull rain through the ridge vent openings.
- Missing end plugs. Open ends admit rain, insects, and wasps.
Leak or condensation?
Drips along the ridge on cold mornings without rain usually mean condensation from moist indoor air, not a roof leak. Check bath fans and air leaks into the attic. Leaks that appear only during windy storms point to the vent or the caps.
How they are fixed
- Remove the caps and vent along the leaking section.
- Correct the slot width and end clearances, and add decking where the slot was overcut.
- Install a baffled vent with a weather filter and end plugs.
- Nail new cap shingles with fasteners long enough to penetrate the deck as the manufacturer requires.
- Remove or disable any fan that pulls through the ridge.
Caulking the vent from above is a temporary patch at best. See common roof leak causes and wind damage to roofs in Georgia.