Attic Air Circulation

In the summer natural air flow in a well vented attic moves super heated air out of the attic protecting roof shingles and removing moisture.

Attic air circulation.

These ice dams form when warm attic air melts the snow on the roof and the water refreezes along the colder edge of the roof. Whole house fans powered attic fans. In hot humid climates ventilation will not keep an attic cool although air circulation combined with an attic fan can help reduce cooling costs. Fans and vents may be installed on the roof system that will draw the air out of the attic space and exhaust it to the exterior.

Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents. As the attic space warms up from the irradiation of the sun the ventilation port opens wider to allow the solar fan to move more warm stale air out of the attic area. Intake vents located at the lowest part of the roof under the eaves allow cool. If the attic is insulated with fiberglass batts just pull back any that are blocking the flow of air.

That said venting an attic is not always a complete energy efficient solution. Proper air circulation in the attic is all about preventing moisture buildup. If there s blown in insulation like ours rake back the fluffy stuff with a 3 or 4 ft long 1 x 6 or use a garden rake or hoe. Attic ventilation works best in mild to cold climates.

Increased ventilation will make the entire roof cold and reduce or eliminate ice dams. If your attic is well insulated the insulation might be plugging the spaces between rafters just above exterior walls. During the summer soffit and gable vents draw cooler air from outside the house to replace hot air that collects in. That means air can t flow from the soffit vents to the roof vents.

Solar attic fans do just that. These fans may be controlled by a switch or a thermostat which detects heat build up in the attic space and automatically exhausts the attic space. Proper insulation and air sealing also keeps attics cold in winter by blocking the entry of heat and moist air from below. Gable vents may circulate air through only a small percentage of your attic.

Most solar attic fans are surface mounted meaning that they are installed directly through the roof surface where they are most efficient. Static roof line vents are effective for ventilation but generally aren t recommended due to issues with leaks. The ice traps water behind it allowing the water to seep back under the shingles and leak through the roof. Soffit vents may leave air trapped at the top of your attic.