An elevation structure system possesses anti-decubitus ulcer characteristics, and may cooperate with a mattress overlay also having anti-decubitus ulcer capabilities as part of a mattress overlay system, in which multiple elongate, positionally adjustable, relatively moveable risers are configured for selective placement in conditions of transverse, subposed, under-engagement with the sides of an overlay to create substantially non-inclined, elevated, depth-supplemented regions at locations along the length of the overlay. The elevation structure and overlay may each include a dynamic-response core expanse formed of an open-cell, compressible viscoelastic foam coated with an elastomeric, moisture- and gas-flow-managing, differential-thickness coating structure load-transmissively bonded to the entirety of the outside of said core expanse to function as a dynamically-responsive unit therewith.
