Residential: Durability and strength are the fundamental concerns.
Decisions of exposure class should be based upon the service conditions of the structure or structural element, and not upon the conditions during construction.
C Class Concrete pertains to chloride exposure
F Class concrete pertains to freezing and thawing exposure without chlorides
N Class concrete is exposed to neither chlorides nor freezing and thawing. Interior concrete floors with a steel-trowel finish that are not exposed to chlorides, nor to sulphates either in a wet or dry environment