Dallas Roofing: Article About Roof Ventilation
Ventilation is one of the most important aspects of a roofing system. Air that is trapped in the attic heats up on a summer day and increases the cost of cooling the home. During the winter months, warm air from the building's interior rises and may fill the attic space with moisture. The ensuing damage to materials and structural components is often extensive. In order to achieve the appropriate level of intake and outward flow, the roof's ventilation system has to be well designed. For detailed information about the proper placement of vents, property owners can contact a Dallas roofing company. Widely accepted standards have been set by the ICC, ASHRAE and HUD. At least one square foot of ventilation without netting must exist per 150 square feet of attic space. With an even balance of openings at the ridge and eaves, the recommendation is reduced to one square foot of ventilation for every 300 square feet in the attic. Some manufacturers include minimum attic ventilation requirements in their roofing material warranties.
A common mistake among homeowners is covering soffit and rafter vents when installing insulation. Fresh air must be free to flow in through these apertures and along the underside of the roof decking. If the vents are not properly located, they can become blocked by dirt or debris. Rain or snow may even blow into the structure and wreak havoc on the materials inside.
The roofing contractors at Total Roofing of Dallas can assist you with any questions regarding emergency repairs or roof maintenance.
An experienced roofer can determine what size the vents at the eaves and ridge should be so that the incoming air will continually flow in one direction. For the desired result, ventilation can be attained through either natural or mechanical means.
Natural air flow occurs through a combination of the wind and stack effect. The force of the wind must be strong enough to foster an adequate breeze and force air into the attic. Since warm air rises, the pressure at the top of the attic is higher than at the bottom. This stack effect helps the high pressure outside to push air into the attic at the eaves where the pressure inside is low. Likewise, the high pressure at the top of the attic space pushes air through the openings to the lower pressure area just outside the ridge vents.
Attic fans can achieve mechanically driven ventilation by sucking air in through the soffit or gable openings and then pushing hot air out at the ridge. In order to accomplish an adequate flow with fans, however, the vents must be kept clear at all times. Blocked vents cause the fans to draw cool air from the building's interior, resulting in higher energy costs.