Subfloors that are listed below quality (underground) or ground level floors in buildings without basements generally have a concrete subfloor. Subfloors above quality (above ground) generally have a plywood subfloor.
There is no such point as a maintenance-free floor. Rug needs vacuuming and periodic deep cleaning. Wood floorings require cleaning, waxing, and also periodic refinishing. Also hard-wearing ceramic floor tiles should be grout-sealed as well as mopped.
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