Installing insulation in your attic is an important step to ensure your home is comfortable and energy efficient. However, it is also essential to make sure that the attic is properly ventilated after the insulation is installed. Blocking airflow in the eaves is a common mistake that homeowners make when installing insulation, so it is important to use girder vents and roof vents to maintain airflow. Attic ventilation can lower the temperature of the attic air and reduce the temperature of attic surfaces by convection, which is important to reduce the need for air conditioning and to stay comfortable.
The ceiling finish reflects part of the radiant heat, while the rest is absorbed and conducted to the bottom of the roof covering. In addition to heating attic air, heat is transmitted to attic surfaces by long-wave radiation, including the ducts and the upper part of the roof insulation. To remove this heat, the attic air must be replaced by cooler outside air. Make sure that the vents are sized to provide an equal open area for entrances and exits. Building codes generally require a free ventilation area of one square foot for every 150 square feet of roof.
A continuous baffle must be installed on the eaves to prevent the insulation from blocking air flow. The key to an effective insulation system is the proper installation of quality insulation products. A building must have a continuous layer of insulation around the entire building envelope, without gaps or compression. This is considered their “thermal wrap”.
Studies show that a poorly installed thermal envelope can reduce overall performance by 30 percent or more. Installing rectangular vents on the ceiling is as simple as cutting the holes and screwing the vent into place. First, mark the ventilation position of the roof from the attic. You should be able to see the beams to avoid placing ventilation holes over them. If the ceiling runs parallel to the street, place the vents at the back to make them less prominent. Ventilated attics can introduce additional moisture loads to Florida homes by allowing moisture-laden air to enter the attic that can communicate with the interior.
I have a large attic with ridge-shaped vents and vents at each end of the attic to keep air flowing. Both of these features help increase the effectiveness of your insulation system, keeping your attic dry but not hot. Due to moderate conditions surrounding duct systems, size of air conditioning systems may be slightly reduced and maintenance of attic air controllers is easier. Insulation with greater resistance (higher R-value) to heat flow means that less heat enters house during warm months and less heat comes out in cold months when interior space is heated. In addition, overall R-value of wall or roof will be somewhat different from R-value of insulation itself since some heat flows around insulation through posts and beams in wooden or steel frame structures (thermal bridges).Attic insulation is critical because more heat passes per square foot through roof than in any other structure in home.
For more information on insulating materials, if any, installation methods and advantages, see Types of Insulation. The accumulation of stale air in an attic can increase humidity levels, making it feel uncomfortably hot and poorly ventilated. Ceiling vents are designed to promote airflow and expel stale air from an attic to maintain a comfortable indoor temperature. You can measure how thick your attic insulation is with a ruler and multiply that number by its R-value rating for an insulation rating. If you want to put an office in your attic but there's a ventilation grill in your roof where you want it, you can either leave it open and build around it or close it off.
Sealed attics can help reduce moisture condensation in ductwork and air handlers mounted in attics by reducing humidity levels around ducts and on back sides of ceiling drywall when using low thermostat set points. The importance of properly sealing off an airtight attic for it to function properly means that post-construction testing is recommended to ensure there are no airflow paths between an attic and outside. Life cycle analysis, environmental impact, and human health issues associated with resource extraction, manufacturing, use, and disposal of insulation are also important considerations.
