A part of preventive maintenance is to have properly placed and sized door mat.
Door mat should be placed entryways and elevators and should be sized to cover
the distance of several footsteps. There purpose is collect dirt before it
reaches the carpeted area. According to the Carpet and Rug Institute, they cover
an "average 90 square feet (6 x 15) at building entrances, 10 square feet (2 x
5) at internal doorways, and 40 square feet (5 x 8) in corridors six feet wide."
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