A cantilever stair assembly for installation in segments or sections includes a stair tread module including a stair tread plate having a tread hole. An embedded stair tread is inserted into and fixed within the tread hole. The stair tread module may include a first inner wall stair tread support and a second inner wall stair tread support for mounting to opposite sides of a vertical support member. Each of the first and second inner wall stair tread supports has a first plate with a plurality of support-member-engagement holes therethrough and a second plate perpendicular to the first plate and having a plurality of stair-tread-plate-engagement holes therethrough. The stair tread plate is secured to at least one of the plurality of stair-tread-plate-engagement holes of each of the first and second inner wall stair tread supports.

An improved folding stair comprising a sequence of steps (101), each rotably mounted to a structure (102) via axes (103) located and oriented to facilitate rotation between deployed and stowed states, such that the steps exhibit tread overhang (109) in their deployed state. The step width (105) exceeds the step rise (107). In other embodiments the axes are to one side of the steps. In other embodiments the angle of rotation between deployed and stowed states exceeds the arccosine of step-above thickness (104) over step rise. In other embodiments the movement from deployed to stowed state moves the steps from the traversal path. In other embodiments the axes are either skew to the deployed tread, or to the traversal path, or to both. Other embodiments include a means of coordinating the steps' folding motion.

A cantilever stair assembly for installation in segments or sections includes a stair tread module including a stair tread plate having a tread hole. An embedded stair tread is inserted into and fixed within the tread hole. The stair tread module may include a first inner wall stair tread support and a second inner wall stair tread support for mounting to opposite sides of a vertical support member. Each of the first and second inner wall stair tread supports has a first plate with a plurality of support-member-engagement holes therethrough and a second plate perpendicular to the first plate and having a plurality of stair-tread-plate-engagement holes therethrough. The stair tread plate is secured to at least one of the plurality of stair-tread-plate-engagement holes of each of the first and second inner wall stair tread supports.

Some implementations can include step pegs having safety locks.

A stair system according to one illustrative embodiment comprises: a support body mountable in a wall and comprising a connecting region; a stair body; and a mounting apparatus. The mounting apparatus comprises: a connector connectable to the connecting region of the support body in any one of a plurality of different positions in the connecting region of the support body; and a holder configured to hold the stair body such that when the connector is connected to the connecting region of the support body, the stair body is spaced apart from the support body to permit a wall panel between the stair body and the support body. Wall assemblies comprising such stair systems are also disclosed.

A stair system according to one illustrative embodiment comprises: a support body mountable in a wall and comprising a connecting region; a stair body; and a mounting apparatus. The mounting apparatus comprises: a connector connectable to the connecting region of the support body in any one of a plurality of different positions in the connecting region of the support body; and a holder configured to hold the stair body such that when the connector is connected to the connecting region of the support body, the stair body is spaced apart from the support body to permit a wall panel between the stair body and the support body. Wall assemblies comprising such stair systems are also disclosed.

A simplified staircase 1 includes a plurality of girders 3 that form a plurality of steps Each of the girders 3 includes one or more first protrusions 17 that protrude from a front side of an upper surface of each of the girders 3. Each of the girders 3 further includes one or more second protrusions 15 that protrude from a rear side of the upper surface of the girder 3. The one or more second protrusions 15 are higher than the one or more first protrusions 17 in height.

An improved folding stair comprising a sequence of steps (101), each rotably mounted to a structure (102) via axes (103) located and oriented to facilitate rotation between deployed and stowed states, such that the steps exhibit tread overhang (109) in their deployed state. The step width (105) exceeds the step rise (107). In other embodiments the axes are to one side of the steps. In other embodiments the angle of rotation between deployed and stowed states exceeds the arccosine of step-above thickness (104) over step rise. In other embodiments the movement from deployed to stowed state moves the steps from the traversal path. In other embodiments the axes are either skew to the deployed tread, or to the traversal path, or to both. Other embodiments include a means of coordinating the steps' folding motion.