Sentence:  Argiento had been trained so rigorously by the Jesuits that Michelangelo was unable to change his habits : up before dawn to scrub the <WSD>floors</WSD> , whether they were dirty or not ; water boiling on the fire for washing laundry every day , the pots scoured with river sand after each meal . 
Meaning of the word marked with <WSD> tags:  the inside lower horizontal surface (as of a room, hallway, tent, or other structure)