Moisture In Attic In Winter

First warm and moist air rises up from the living space below and gets trapped in your attic space.

Moisture in attic in winter. Attic moisture in winter moisture vapor from daily activities such as cooking bathing and laundry can rise into your attic especially in winter when windows and doors are kept closed. Hot summer weather poses the opposite problem for maintaining recommended attic temperatures. If it s winter and it s much colder outside as is often the case when that warm moist air comes in contact with the cold underside of your roof deck you get condensation. Condensation in attic in winter.

The difference in the two spaces is the dry bulb temperature. Our main concern in the winter is moisture. Moisture from daily activities such as cooking bathing and laundry can rise into your attic especially in winter when windows and doors are closed. If it s cold outside and warm air from indoors makes it to the underside of your cold roof this air begins to decrease in temperature and releases it s moisture content along the way.

If there is excessive moisture accumulation in your attic it will condense on cold areas mainly on the underside of your roof deck. The first signs of a condensation problem in your attic might show up during a re shingle on your roof. There are several reasons why you are finding moisture in your attic during winter. Warm air simply holds more water vapor than cold air.

The reason is that during the winter fans such as the one in your bathroom would send air saturated with moisture into the attic directly onto frigid roof boards. Remember the example of the cold glass in the summer. Cold outdoor temperatures especially below freezing can wear on your furnace. Looking for signs of moisture.

By adding moisture to the lower floor you increase the partial pressure of the water vapor which pushes it to areas of lower vapor pressure like the attic. So they equalize pretty quickly. In the winter the condensation will form frost and in the summer this condensation can grow mold. During the winter months the recommended relative humidity inside a house is anywhere between 30 50 percent.

Ideal attic temperature and humidity settings cold outdoor temperatures affect attics. If you raise the attic temperature the rh in both places would be the same. It is unlikely that under these conditions normal attic ventilation would effectively remove this moisture laden air before ice formed on the roof decking. If there are signs of rot on the roof sheathing then there has been prolonged moisture in the attic.