Abstract: A step module is provided for use in constructing stairways. Each step module includes a tread portion and a riser portion connected at a nosing so that a plurality of modules may be secured adjacently in stepwise fashion to create a stairway. A shoulder member attaches to the riser portion of one module along the front riser surface parallel to the nosing and thus forms a tread seat for attachment of the distal tread edge of a lower module. When connected, a channel is formed which may be enclosed and filled with a filler material such as an acoustical damping material. The cover may be a wing projecting forwardly of the riser portion and underlying the tread portion of the lower module.