The answer to 'roof vent ice dam' is that a roof vent ice dam occurs when ice builds up around a roof vent, preventing proper ventilation and causing water to back up under the shingles. This can lead to leaks, water damage, and further ice dams forming.
Common causes include poor insulation, inadequate ventilation, and warm air escaping through the vent. Symptoms include icicles around the vent, water stains on the ceiling, and ice buildup on the roof. Solutions may involve improving insulation, adding ventilation, or clearing the ice dam, but severe cases may require a professional roofer to address the underlying issues.