Moisture is considered to be one of the biggest threats a home can face, but with the proper ventilation, a roof and home can be protected from damage. Ventilation systems are a necessity in attics and are also required by the International Building Code. The roofing system, which consists of shingles, ventilation and insulation products, work together to help extend your roof’s life, save money on heating and cooling costs and reduce your greenhouse gas emissions.
The purpose of ventilation is to allow fresh air into the attic and to expel excess heat and moisture out. A family of four produces two to four gallons of water vapor from cooking, bathing and laundry every day. Over one gallon is produced simply from breathing and perspiration.
Proper ventilation keeps attics cooler in the summer months and reduces moisture and prevents the formation of ice dams during the winter months. Without proper ventilation, heat buildup in the summer can cause premature aging and cracking of the wood and roofing materials. This additional heat can also reduce energy efficiency in the home.
During the colder months, warm air that is generated through everyday activities, like doing laundry and showering, can cause moisture buildup in the attic. If the moisture isn't properly vented from the attic, it can cause mold, mildew or wood rot to develop, compromising the quality of the air inside the home and resulting in costly damages to fix.
When installing a ventilation system, contractors need to determine the correct amount of ventilation needed for the attic space, known as the Net Free Area (NFA). The minimum ventilation ratio is 1:150, which means the system needs to have one square foot of vent area for each 150 square feet of attic/roof area. A good ventilation system is a balanced system with 50% intake ventilation and 50% exhaust ventilation. An attic that is properly sealed and insulated will help prevent conditioned air from escaping into the attic, thus making the home more comfortable and energy efficient.
A properly installed ventilation system will naturally cycle air through the attic, flushing out any moisture from inside the home, thus protecting your roof and home from mold, ice dams, irregular temperatures inside the home and other damages.
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