Configuring Attic Ventilation Based On Outside Temperature

Up to 140 f 60 c.

Configuring attic ventilation based on outside temperature.

This prevents snow from melting on your roof and freezing when it hits the cold gutter. These images came from a presentation danny parker gave pdf on fsec s cool roof research the third graph shows attic temperatures from the middle of the attic for several different types of roofing as well as a sealed attic. But in the winter the amount of water vapor that the air can hold is substantially lower. Proper insulation but poor ventilation will lead to high temperatures and thus high humidity.

Roof shingle temperatures will be higher during no wind conditions leading to a higher heat load on the attic. Ideal attic temperatures shouldn t be more than 10 to 20 degrees hotter than outside temperatures. Attic temperature depends on the amount of solar radiation construction details and the rate of ventilation. Temperature at roof sheath.

The white roof lowered the attic temperature by about 20 f. In the summertime the outdoor air temperature as well as the air inside the attic is warmer than it is in the winter and warmer air can hold more moisture than cold air can. Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents. Temperature in rooms directly beneath attic.

Temperature at attic floor. You can test the temperature level using a couple of thermometers. If your attic soars above 100 degrees and reaches the 150 mark its time to consult professionals. These are typical temperatures for a home with no attic ventilation on a sunny day with an outdoor temperature of 90 f 32 c see figure 1.

The fans cool the attic equalizing the temperature between the attic and outside of the home. As high as 170 f 77 c. Intake vents located at the lowest part of the roof under the eaves allow cool. Ventilation is another key factor.

Attic temperature depends on the outside temperature and it also depends if your house is insulated. Calculations indicate that on a july day in texas a ventilation rate of one air change per minute for a typical attic using 95 degree f air will lower the peak attic temperature to about 101 degrees f.