The load-bearing capacity of a shim depends completely on its material composition, surface area, thickness, and how uniformly the weight is distributed across it. Solid steel or brass shims used in heavy industrial machinery can withstand immense compressive loads scaling to tens of thousands of pounds without deforming. Conversely, standard wooden or plastic construction shims used in residential framing handle moderate loads, but soft or compressible materials can crush, creep, or extrude under excessive localized pressure over time.