If slabs do not have a moisture vapor diffusion-retarder underneath, what are they considered in terms of finishing?

When slabs lack a moisture vapor diffusion-retarder underneath, they are often classified as not suitable for finished flooring. This is because moisture from the ground can migrate through the concrete slab, leading to potential issues such as mold growth, damage to flooring materials, and deterioration of adhesives and finishes. Without a good barrier in place, the risk of moisture-related problems increases significantly, making it challenging to maintain a durable and aesthetically pleasing finished floor.

Other options might suggest that slabs in this condition could be suitable for finished flooring or certain types of installations, but the absence of a moisture vapor retarder is a critical factor. Adequate moisture control is essential for the longevity and effectiveness of flooring systems, so in this case, it is important to avoid finishing a slab that does not provide the necessary protection against moisture infiltration.