Attic Air Circulation

Most solar attic fans are surface mounted meaning that they are installed directly through the roof surface where they are most efficient.

Attic air circulation.

Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents. Gable vents may circulate air through only a small percentage of your attic. Increased ventilation will make the entire roof cold and reduce or eliminate ice dams. Soffit vents may leave air trapped at the top of your attic.

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. The insulation will resist heat transfer into the house. Attic ventilation works best in mild to cold climates. Proper insulation and air sealing also keeps attics cold in winter by blocking the entry of heat and moist air from below.

Baffles are available at home centers. 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. Solar attic fans do just that. The solution is to add baffles which allow air to flow past the insulation photo 9.

Static roof line vents are effective for ventilation but generally aren t recommended due to issues with leaks. During the summer soffit and gable vents draw cooler air from outside the house to replace hot air that collects in. Whole house fans powered attic fans. 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.

In hot humid climates ventilation will not keep an attic cool although air circulation combined with an attic fan can help reduce cooling costs. The ice traps water behind it allowing the water to seep back under the shingles and leak through the roof. That means air can t flow from the soffit vents to the roof vents. 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.

If the attic is insulated with fiberglass batts just pull back any that are blocking the flow of air. If your attic is well insulated the insulation might be plugging the spaces between rafters just above exterior walls. Intake vents located at the lowest part of the roof under the eaves allow cool. 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.