Such a climate condition causes vapor to migrate into an insulated roof system where it can cool and condense into water. Buildings with high interior relative humidity require vapor retarders, as well as buildings located in the Central and Northern regions of the United States. For such buildings, the designer shall calculate the roof assembly dew point so as to determine the correct location to install the vapor retarder within the roof system. Included in the calculations shall be the R-value of the roof assembly components, anticipated interior and exterior temperatures, regional temperatures, the building's planned relative humidity, and any other pertinent data. The Three Primary Moisture Control Factors 1.
Ventilation is the exchanging of air in a given space.
Passive or mechanical ventilation is designed to control moisture and reduce heat buildup. Exchanging the air in a given space is accomplished by venting moisture-laden air to the outside, while inducing fresh outside, or conditioned drier air to the inside. Insulation provides R-value and aids in temperature control within a building. Insulating a roof reduces the amount of energy required to heat and cool a building and can also reduce the potential for condensation on interior surfaces or within the roof assembly. A vapor retarder is a Fields two or more sheet waterproof membrane adhered and coated with Fields asphalt.