Roof ventilation is based on simple facts – warm air rises. During high temperatures of the summer the sun heats the air in the attic. During the cold winter temperatures the warm air in your home heats up the air in the attic. Good ventilation occurs in either season when cool air can enter the attic near the eaves and exit near the peak. The ultimate goal of roof ventilation is that the temperature and humidity levels in the attic space match the conditions outdoors.
Aspects of Good Ventilation
- Soffit Vents – best for intake air.
- Ridge Vents or Hood Vents – air can passively exit through ridge vents or hood vents.
- Turbine Vents – harness the wind to suck air out of the attic.
- Electric-powered Vents – the ultimate air movers. These vents are not always necessary.
- Gable Vents – help the air flow evenly throughout the attic.
Side Effects of Bad Ventilation
- Structural damage to your home. The water can also drip onto and through the ceiling, causing further damage.
- Ice dams occur when the attic gets warm enough to melt snow on the roof while the eaves are still cold. When the snow melts and reaches the eaves it freezes and forms a dam eventually finding its way under the shingles.
Ventilation Basics
- It is not unusual for soffit vents to get plugged by cobwebs, stray insulation or other debris. Clearing your soffit vents is easy to do with a leaf blower or a compressor and an air nozzle. Be sure to wear eye protection when doing so.
- Is your roof free of snow when all of the neighboring roofs are snow-covered? Do a quick check of your attic for proper insulation. Your roof may have a warmer southern exposure but it could also indicate that your roof has poor ventilation.
- It is reasonable to think that better ventilation would lessen the radiated heat and reduce the load on your cooling system. Most studies find that home owners garner minor savings with improved ventilation. Adding attic insulation is usually much more effective.
- Proper ventilation helps to keep your shingles cooler, extending the life of the roof. The effect of ventilation on shingle life depends on many factors:
- Climate is just one.
- Warranties – Most shingle manufacturers void their warranties if roof venting standards aren’t met.