Abstract: A self-adjustable stair construction wherein the treads of the stair are supported by spacers between parallel upper and lower stringers in a truss assemblage. The rise and run and nosing are simultaneously adjusted for each tread with the adjustments being cumulative for each stair flight total run while maintaining the treads level. Each tread is located in a right angle relationship with each spacer. The treads, spacers and stringers are pivotally connected together with an elongated slot formed in each spacer to permit the adjusting movement. The slots are inclined and may be either curved or straight with the slope of either being in substantial alignment with the direction of the adjusting movement. The minimum number of repeated parts to produce the whole stair may be two.

Abstract: A stair construction in which a stair tread member is releasably clamped in position upon a pair of spaced tread support frame members in a manner such that a tubular sleeve of carpeting or other flexible tread covering material is simultaneously snugly, yet releasably, fitted in place on the tread member. The construction includes a pair of individual side frame assemblies in a parallelogram linkage form wherein the inclination of the prefabricated side frame assemblies can be adjusted as required in the field while maintaining the tread support frame members in a true horizontal position.