Soffit Vents: Controlling Attic Heat and Moisture
Soffit vents, also called undereave vents, are a type of attic ventilation that's typically installed on a hip roof. This type of vent usually looks just like the material that's used to finish the underside of the roof overhang such as ordinary soffit boards, soffit metal or even vinyl. Soffit vents are often unrecognizable except by people who are familiar with them.
Older Home versus Newer Home Ventilation
Older homes typically don't have soffit siding vents installed unless a homeowner has added the vent after the house was built. This is because older homes don't have the same venting needs as newer homes. The ventilation that was built into older homes, little as it was, was adequate at the time because homes were draftier than the more insulated homes built today. Air moved easily from outside the home to inside through the openings around doors and windows, lowering the humidity inside the house.
Dangerous Attic Heat
Proper ventilation in your attic can lower the temperature of that space, which will in turn lower your energy bills. Bringing down the temperature of your attic space has the added advantage of making the space safe for you to enter on extremely hot days. The temperature in an attic that isn't properly ventilated can reach a dangerous 160 degrees. A person spending only a few minutes in such an environment could suffer from heat exhaustion very quickly.
While making modern homes far more energy efficient, eco-friendly construction practices such as improved insulation and weather stripping prevent most of the air exchange that naturally ventilated older homes. Newer more airtight homes are more vulnerable to humidity because the cooler, dryer outdoor air can't mingle with the warmer inside air. The result is the buildup of more humidity that can't escape due to improved sealing. This moisture accumulates in the attic space and if the attic is not well-ventilated, condensation and frost can form beneath the roof.
Continuous versus Individual Soffit Vents
A soffit aluminum vent on your home that runs the length of the eaves is called a continuous vent. These were usually installed on homes with very narrow eaves to give maximum ventilation. Individual soffit vents are easier to install by yourself because they're small enough for one person to handle, typically fitting between two soffit joints.
Newer homes should have one or more soffit vents installed, and they should not be the only attic vents on the home. Mixing several different types of vents best ensures that your attic stays cooler in the summer and drier in the winter. Without soffit vents and other proper ventilation in your attic the extreme heat and the dampness of this condensation combine to damage your roof during the summer and winter. If you don't have soffit vents, adding one or more can help lower your cooling bills while extending the life of your roof.