Why are emulsions described as breathable?

Emulsions are described as breathable primarily because the applied film is vapor permeable and aids in damp proofing. This permeability allows moisture in the form of vapor to escape from the underlying substrate while preventing liquid water from penetrating into the roofing system. This characteristic is crucial in roofing applications where moisture control is essential to prevent damage from trapped moisture, which can lead to mold growth, degradation of roofing materials, and structural issues.

The vapor-permeable nature of emulsions promotes a balanced moisture environment, enabling any humidity generated below the roofing surface to dissipate. This is particularly important in built-up roofing (BUR) systems, which often involve multiple layers of material, as it helps to maintain the integrity of the roof over time while also providing damp-proofing properties.

Other options, while related to moisture management, do not capture the primary reason for comparing emulsions to breathable materials. For instance, enhancing airflow beneath roofing material (though beneficial) does not directly correlate with the breathability of emulsions. Likewise, preventing moisture accumulation, while a goal in roofing systems, does not effectively describe the specific function of emulsions in terms of vapor permeability.