The present invention relates to a prefabricated spiral staircase in which the heights between treads can be freely and finely adjusted, thus being conveniently assembled and installed at installation sites having different story heights.

Systems and methods for constructing staircases are described herein. The systems include a stringer hanger bracket for coupling a stair stringer of the staircase to an upper floor, two or more tread support structures and a jig. Each tread support structure is configured to couple a tread to the stair stringer. The jig is configured to determine a mounting position of each of the tread support structures on the stair stringer, determine a mounting position of each of the tread support structures on the stair stringer and/or determine a length of the stair stringer.

A stair assembly includes at least one joist comprising an upper wall, a first lateral wall extending from the upper wall, and a second lateral wall extending from the upper wall. At least one stair step support bracket includes a tray support wall, a first side wall extending from the tray support wall, and a second side wall extending from the tray support wall. The first and second side walls define a pair of first front aligned positioning holes configured to receive a first set pin and a pair of first rear aligned positioning holes configured to receive a second set pin. The pairs of first front and rear aligned positioning holes disposed such that when the first and second set pins received therethrough contact the upper wall of the at least one joist, the tray support wall is positioned at a first rise dimension.

A bilateral bracket for steps to be fixed on a stringer having a number of steps and risers, the bilateral bracket having a generally flat body defining a framing edge having a riser edge and a tread edge; the riser edge having a riser flange perpendicularly extending therefrom in a first direction; the tread edge having a tread flange perpendicularly extending therefrom in the first direction, wherein the tread extends between a distal end and a proximal end; the framing edge defining an acute angle relative to each other, wherein the flat body does not project beyond a profile defined by the distal and proximal ends inward of a profile defined by the framing edge; and a stringer edge along the body, opposite the framing edge, wherein the stringer edge has an array of holes for selectively attaching to either side of the stringer.

A stair stringer includes a pair of joists each including an upper wall, a first lateral wall extending from the upper wall, and a second lateral wall extending from the upper wall. At least one stair step support bracket includes a tray support wall, a first side wall extending from the tray support wall, a second side wall extending from the tray support wall, and a front wall extending between the first side wall and the second side wall. The at least one stair step support bracket is configured to set on the upper wall of one of the pair of joists and the first side wall extending downward beyond the upper wall of the one joist in position to receive a first fastener through the first side wall and into the first lateral wall of the one joist, and the second side wall extending downward beyond the upper wall of the one joist in position to receive a second fastener through the second side wall and into the second lateral wall of the one joist, wherein the tray support wall is level.

A self-leveling staircase. The staircase has a first flight of self-leveling steps having a first end adjacent to the ground and a plurality of stair treads pivotally attached at a right edge to a first pair or stair rails and at a left edge to a second pair of stair rails. A self-leveling platform is pivotally attached on a second end of the first flight of self-leveling steps and to the first and second pair of stair rails. A second flight of self-leveling steps having a first end is pivotally attached to an opposite side of the self-leveling platform from the first flight of self-leveling steps. The second flight of self-leveling step has a plurality of stair treads pivotally attached at a right edge to a third pair of stair rails and pivotally attached at a left edge on front and back ends thereof to a fourth pair of stair rails.

The stair system is made of a deck plate attached to an existing structure (such as a deck) and to the top end of a pair of stringer beams. A base plate is attached to the bottom end of the pair of stringer beams. Next a plurality of steps are attached to the pair of stringer beams, the steps being comprised of a tread assembly, a pair of tread brackets and at least one intermediate support bracket. The steps can be integrally formed or made of modular components which are connected together to form the step. Finally, the decking material is attached to the step.

A self-leveling staircase. The staircase has a first flight of self-leveling steps having a first end adjacent to the ground and a plurality of stair treads pivotally attached at a right edge to a first pair or stair rails and at a left edge to a second pair of stair rails. A self-leveling platform is pivotally attached on a second end of the first flight of self-leveling steps and to the first and second pair of stair rails. A second flight of self-leveling steps having a first end is pivotally attached to an opposite side of the self-leveling platform from the first flight of self-leveling steps. The second flight of self-leveling step has a plurality of stair treads pivotally attached at a right edge to a third pair of stair rails and pivotally attached at a left edge on front and back ends thereof to a second pair of stair rails.

The stair system is made of a deck plate attached to an existing structure (such as a deck) and to the top end of a pair of stringer beams. A base plate is attached to the bottom end of the pair of stringer beams. Next a plurality of steps are attached to the pair of stringer beams, the steps being comprised of a tread assembly, a pair of tread brackets and at least one intermediate support bracket. The steps can be integrally formed or made of modular components which are connected together to form the step. Finally, the decking material is attached to the step.

A stair stringer includes a pair of joists each including an upper wall, a first lateral wall extending from the upper wall, and a second lateral wall extending from the upper wall. At least one stair step support bracket includes a tray support wall, a first side wall extending from the tray support wall, a second side wall extending from the tray support wall, and a front wall extending between the first side wall and the second side wall. The at least one stair step support bracket is configured to set on the upper wall of one of the pair of joists and the first side wall extending downward beyond the upper wall of the one joist in position to receive a first fastener through the first side wall and into the first lateral wall of the one joist, and the second side wall extending downward beyond the upper wall of the one joist in position to receive a second fastener through the second side wall and into the second lateral wall of the one joist, wherein the tray support wall is level.