ATTIC VENTILATION MYTHS
5 ATTIC VENTILATION MYTHS BUSTED
Attic ventilation is one topic in the building industry that raises very varied opinions and recommendations. While ventilation is all about keeping air in the house fresh and moistures levels low, many myths abound about attic ventilation. Here are some of those myths busted.
Roof Vents Equal Roof Ventilation
Not all roof ventilation is equal. In fact, some roof vents do offer very little or no roof ventilation. Ridge vents, for example, are cheap but their efficiency is very questionable. When installed with baffles (blinders that block air crossing the vent), there is practically nil ventilation. Static roof line vents provide effective ventilation but present leak risks. Gable vents are very inefficient as they serve a very low square footage. The most effective ventilation has been seen in ridge and soffit continuous ventilation. Even in these designs, efficiency varies depending on design.
Only Warmer Climates Need Roof Vents
While the importance of roof vents in exhausting hot air from the attic cannot be ignored, their efficiency in warmer climates is overstated. Roof efficiency also depends on other factors like sun exposure, shingle color and insulation. Condensation is not a problem in hotter weather as the moisture is carried outside.
Cooler climates need roof vents as well namely because moisture control is more needed in colder attics. Condensation is a real problem as attics will be cooler and provide a condensation surface for the hot air rising from the house.
The Bigger The Ventilation The Better
Too much ventilation is just as bad as insufficient ventilation. Too many gaps in the roof present potential spots for leaks. Too many ventilation spaces in the roof will make the roof weak against strong winds and hurricanes. If the house is in a wildfire zone, there are risks of sparks getting in through the ventilation.
The ventilation should be proportional. Building experts say the ideal proportion is 1 square foot of ventilation for every 300 square feet of ceiling space. The entire vent opening does not count as ventilation as vent grates present air resistance and interference.
Roof Vents Are Bad For Winter
Some people believe that since warm air rises, roof vents will release warm air in winter putting more demand on the heating system. This is partially true. Warm air rises but for it to escape, the insulation would be the problem. If the insulation is done properly, the house remains warm even with roof vents.
The heating system will only be used where the roofing system has insulation on the roofing deck and has no ventilation. Poor ventilation in the makes moisture laden air accumulates on the underside of the roof. This leads to roof damage from rotting and mold. Roof vents are crucial for letting off this moisture in cold weather which avoids these problems.
Research Studies Are Always True
Research studies are done in controlled lab settings. Regional weather patterns are never perfectly mimicked in these settings. The studies may also not take into account the numerous designs and types of roof structures and roof vents. The fact is that properly installed roofing vents work well in both warm and cold climates.
It is highly advisable to talk to a Calgary roofing expert and have a roof inspection when making decisions on roof vents and attic ventilation. The expert will take into account the design of the current system and its weaknesses before recommending on the best ventilation for your roof.