Carlisle's MiraDRAIN IDB is a high-performance, high-strength drainage composite consisting of a three-dimensional, high-impact polystyrene core and a nonwoven protection fabric bonded to the bottom side. Carlisle's MiraDRAIN IDB is designed for use in inverted roof membrane assemblies (IRMA) to facilitate horizontal drainage under insulation or other overburden materials while protecting the waterproofing membrane.