Attic Air Flows

Grab a flashlight and inspect your attic during the winter.

Attic air flows.

One common problem is caused by ice buildup along the edges of a roof. Gable vents may circulate air through only a small percentage of your attic. The biggest chore is adjusting the air flow valves known as dampers in the ductwork. Ventilation manufacturers assign an nfa value to the non motorized vents they make.

Intake vents located at the lowest part of the roof under the eaves allow cool air to enter the attic. Hot air exhaust vents located at the peak of the roof allow hot air to escape. Nfa is the unobstructed area through which air can pass through a vent usually measured in square inches. Whole house fans powered attic fans.

Make sure there is air flow from the eaves. 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. Air flows in through the soffit vents and out through the roof vents. Intake exhaust airflow in a house attic square footage 2 square inches of exhaust and square inches of intake net free area nfa needed.

This is normally the point where air enters your attic. 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. Vents come in various styles. 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. If you see dampness or frost you need better roof ventilation and some attic vents. Static roof line vents are effective for ventilation but generally aren t recommended due to issues with leaks. And when the ductwork is in an attic fine tuning the process can be a system of trial and error demanding time.

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. For the best results place roof ventilation near the roof s peak and soffit vents in the eaves. Soffit vents may leave air trapped at the top of your attic. 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.