Attic Air Flows

Whole house fans powered attic fans.

Attic air flows. Static roof line vents are effective for ventilation but generally aren t recommended due to issues with leaks. Vents come in various styles. 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. Air flows in through the soffit vents and out through the roof vents.

Grab a flashlight and inspect your attic during the winter. 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. Make sure there is air flow from the eaves. If the soffit of your home isn t perforated to allow air movement either replace it with perforated soffit or install round air vents under the eaves to allow air flow.

The most common mistake homeowners make when installing insulation is to block the flow of air at the eaves. The ice traps water behind it allowing the water to seep back under the shingles and leak through the roof. 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. The biggest chore is adjusting the air flow valves known as dampers in the ductwork.

The insulation will resist heat transfer into the house. For the best results place roof ventilation near the roof s peak and soffit vents in the eaves. Ventilation manufacturers assign an nfa value to the non motorized vents they make. Soffit vents may leave air trapped at the top of your attic.

Gable vents may circulate air through only a small percentage of your attic. Hot air exhaust vents located at the peak of the roof allow hot air to escape. This is normally the point where air enters your attic. One common problem is caused by ice buildup along the edges of a roof.

If you see dampness or frost you need better roof ventilation and some attic vents. Intake vents located at the lowest part of the roof under the eaves allow cool air to enter the 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. Intake exhaust airflow in a house attic square footage 2 square inches of exhaust and square inches of intake net free area nfa needed.