Why is my roof turbine vent not spinning?
Short answer. A turbine vent that does not spin usually has dry or rusted bearings, a bent or out-of-round head that rubs, debris or a nest jamming it, or too little wind and attic intake to drive it. A stuck turbine still lets some air out passively, but it can let rain in and is worth fixing or replacing.
Normal vs a problem
Turbines are driven mostly by wind, with some help from rising warm air. On a still evening it is normal for a turbine to turn slowly or stop. If it stays still on breezy days while the neighbors' turbines are spinning, something is wrong.
Common causes
- Bearings: worn, dry or rusted bearings are the most common cause. Many turbines use sealed bearings that cannot be serviced; others accept a light lubricant.
- Bent head: wind, a falling limb, or someone leaning on it can push the head out of round so it rubs the base.
- Debris and nests: leaves, pine needles, or a bird or wasp nest inside the head.
- Hail damage: dented fins upset the balance and can bind the head.
- Weak intake: without soffit intake there is little upward airflow to help turn it, and it moves little air even when spinning.
- Mixed vents: a turbine near a ridge vent can end up pulling air in instead of out.
Fix or replace
Many turbine heads can be replaced on the existing base, which avoids redoing the flashing. If the base is rusted, or the turbine is one of several mixed exhaust types on the attic, removing it and decking over the hole during a reroof is often the better move, especially if the roof has or will get a ridge vent. Avoid covering a stuck turbine for the winter unless you know the attic has enough other exhaust. See ridge vent vs box vents and roof ventilation basics.