Perhaps you have stared at your roof and wondered what exactly that silver thing sticking out of it is. Is it part of the fireplace? Something to do with the air conditioning? A secret passageway set up for the tooth fairy? It’s amazing how often someone can look at the home that they own and not really notice the pieces that work together to make it function. Those things that stick up out of the roof are called roof exhaust vents, and they are an important part of your home.
Why Are Roof Exhaust Vents Needed?
In short, roof exhaust vents allow air to get outside of the home instead of sitting inside and underneath the roof collecting moisture. Keeping the temperature of the attic as close to the outside temperature as possible prevents condensation.
According to BuildingScience.com, in cold climates, the purpose of roof ventilation “is to maintain a cold roof temperature to avoid ice dams created by melting snow and to vent any moisture that moves from the conditioned living space to the attic.” In hot climates, “the primary purpose of ventilation is to expel solar-heated hot air from the attic or roof to reduce the building’s cooling load and to relieve the strain on air-conditioning systems”. If you live somewhere where the climate varies, the purpose of the exhaust vent varies as well.
Types of Roof Vents
There are many styles of roof vents. The most recognizable, a wind turbine, is usually silver and looks like a fan with a cover. This type of vent has moving parts but is powered by the wind and not by a motor. Another vent with moving parts is the power vent. This type of exhaust vent does require a motor to power fans that keep the air moving through the attic and out of the house. A box vent does not have any moving parts and is harder to see from the street. These are installed over a hole that is cut out in the roof and is square in shape. If you choose this type of vent, expect to need multiples installed. Ridge vents run the entire length of the roof and blend almost seamlessly into the home, creating the best aesthetic in ventilation. Off-ridge vents are similar to box vents but are long and rectangular instead of square in shape. Soffit vents are usually used in conjunction with continuous ridge vents, and provide air intake into the roof ventilation system.
Roof Vent Covers
The types of vents described above vary both in the cover (that you see outside of the roof) and in the placement and amount of holes in the roof. If you want to change the type of cover that you use, for example changing from a wind turbine to a box vent, consult with a local roofer to make sure you can make the switch.