Abstract: A system for building shaft casing for dumb-waiters in a building structure with prefabricated assemblies that are readily stackable over each other. One lower, middle and top assemblies constitute the minimum combination typically used in going from one floor to the next. However, the middle and upper assemblies can be repeated depending on the structure where the system is installed. The assemblies include each four elongated corner members with respective ends that receive connecting pin members that permit the structurally stable stacking up of the assemblies. A central and continuous passage is defined. The lower assembly includes two apertures with adjacent compartments within the central passage one to have access to the dumbwaiter and the other one to access the motor and control means. The top assembly has an aperture to provide access to the sprocket mechanism used with the chain that suspends the dumbwaiter within the shaft casing.