Attic Ventilation Air Flow

In other words the entire vent opening doesn t count as vented space.

Attic ventilation air flow.

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. Generally speaking you need a ratio of 1 300 where for every 300 square feet of ceiling space you need 1 square foot of attic ventilation. Intake exhaust airflow in a house attic square footage 2 square inches of exhaust and square inches of intake net free area nfa needed. Effective attic ventilation systems reduce damaging heat and moisture in your attic promote energy efficiency by helping to reduce the load on your air conditioner in the summer and also reduce the risk of ice dam formation on your roof.

Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents. Air follows the path of least resistance. Ventilation manufacturers assign an nfa value to the non motorized vents they make. Nfa is the unobstructed area through which air can pass through a vent usually measured in square inches.

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. Proper attic ventilation can help reduce the load on your air conditioner. In a properly designed and installed attic ventilation system that means the air will flow from the intake vents to the exhaust vents flushing out the warm moist air along the entire underside of the roof deck. Ventilation can be accomplished using various products and techniques.

To calculate the amount of ventilation you need for your home visit gaf s ventilation calculator now. For the best results place roof ventilation near the roof s peak and soffit vents in the eaves. The insulation will resist heat transfer into the house. A new roof is more than just shingles.

Grab a flashlight and inspect your attic during the winter. That said air resistance and interference such as vent grates reduces the area of true ventilation. Intake vents located at the lowest part of the roof under the eaves allow cool. Before we explore how to ventilate an attic space it is prudent to understand how much ventilation is needed.

Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca. Increased ventilation will make the entire roof cold and reduce or eliminate ice dams. The most common mistake homeowners make when installing insulation is to block the flow of air at the eaves. Air flows in through the soffit vents and out through the roof vents.