Stair system with adjustable width

Abstract

A stairway assembly having an external step portion, an internal step portion slidably engaged with the external step portion; a first stringer secured to the external step portion to support the external step portion; and a second stringer secured to the internal step portion to support the internal step portion.

1 . A staircase assembly comprising:
 a plurality of stringers having a series of substantially equally spaced substantially vertical structure notched out of one side to define the height of each step of the stair system, and a series of substantially equally spaced substantially horizontal structure notched out of one side to define the length of each step of the stair system;   a central stringer disposed between at least two other stringers;   a substantially vertically oriented riser;   a substantially horizontally oriented tread that extends horizontally from a lower end of said vertically oriented riser to form a step at the lower end of the riser, and to define a riser and tread boundary;   a rounded extension piece offset from said riser and tread boundary;   a different riser having a receiving groove portion that is capable of receiving said rounded extension piece to define a stair unit; and   a plurality of stair units, having a substantially vertically oriented riser and a substantially horizontally oriented tread;   whereby the stairs can be adjusted laterally via lateral sliding between the receiving groove and the first projecting structure.   
   
   
       2 . A staircase assembly as defined in  claim 1  wherein said assembly further comprising said substantially horizontally oriented tread and said substantially vertically oriented riser having bolt holes therein a handrail post;
 said substantially vertically oriented riser having a handrail aperture therein, said handrail aperture capable of receiving said handrail post;   whereby said substantially horizontally oriented treads and said substantially vertically oriented risers are secured to said stringers by bolting said treads to said stringers via said bolt holes.   
   
   
       3 . A staircase assembly as defined in  claim 1 , wherein said substantially vertically oriented riser having a jutting projection for holding said tread of immediate upper stair unit. 
   
   
       4 . An adjustable staircase assembly as defined in  claim 1 , wherein said assembly further comprising an adjustable central support frame for supporting said treads. 
   
   
       5 . An adjustable staircase system as defined in  claim 1 , wherein said assembly has a railing. 
   
   
       6 . A staircase assembly comprising:
 a plurality of stringers having a series of substantially equally spaced substantially vertical structure notched out of one side to define the height of each step of the stair system, and a series of substantially equally spaced substantially horizontal structure notched out of one side to define the length of each step of the stair system;   a central stringer disposed between at least two other stringers;   a riser having a vertical portion and a horizontal portion, and a receiving groove disposed therebetween;   a tread having a vertical portion and a horizontal portion; and a first projecting structure extending away from said tread; said first projecting structure capable of being received within said receiving groove;   said tread extends substantially horizontally away from said first projecting structure to form a lip; and   a plurality of stair units, having said riser and said tread; whereby the stairs can be adjusted laterally via lateral sliding via the receiving groove and the first projecting structure.   
   
   
       7 . A staircase assembly as defined in  claim 6  wherein said assembly further comprising said tread and said riser having bolt holes therein
 said riser having a handrail aperture therein, said handrail aperture capable of receiving said handrail post;   whereby said treads and said risers are secured to said stringers by fastening said treads to said stringers via said bolt holes.   
   
   
       8 . A staircase assembly as defined in  claim 6 , wherein said riser having a jutting projection for holding said tread of immediate upper stair unit. 
   
   
       9 . An adjustable staircase assembly as defined in  claim 6 , wherein said assembly further comprising an adjustable central support frame for supporting said treads. 
   
   
       10 . An adjustable staircase system as defined in  claim 6 , wherein said assembly has a railing. 
   
   
       11 . A stairway assembly comprising:
 an external step portion ( 500 );   an internal step portion ( 600 ) slidably engaged with said external step portion ( 500 );   a first stringer ( 790 ) secured to said external step portion ( 500 ) to support said   external step portion ( 500 ); and   a second stringer ( 750 ) secured to said internal step portion ( 600 ) to support said internal step portion ( 600 ).   
   
   
       12 . The apparatus of  claim 11 , further comprising:
 a central stringer ( 770 ) secured to said internal step portion ( 600 ) to support said internal step portion ( 600 ), said central stringer ( 770 ) disposed between said first stringer ( 790 ) and said second stringer ( 750 ).   
   
   
       13 . The apparatus of  claim 11 , wherein said external step portion ( 500 ) further comprises:
 an external riser ( 312 ) oriented substantially vertical, and extending substantially from said external riser ( 312 ) is an external runner ( 320 ) oriented substantially horizontal to form a step; as said external runner ( 320 ) extends away from said external riser ( 312 ), said external runner ( 320 ) forms a downward curving lip ( 440 ).   
   
   
       14 . The apparatus of  claim 13 , wherein said downward curving lip ( 440 ) is in slidable engagement with an internal step portion downward curving lip ( 540 ). 
   
   
       15 . The apparatus of  claim 11  wherein said external step portion ( 500 ) and said internal step portion ( 600 ) are each about 33 inches in width, and thus can slidably engage to a stairwell that is about 66 inches in width. 
   
   
       16 . The apparatus of  claim 13  wherein the downward curving lip ( 440 ) has an arm ( 442 ) that extends downwardly to a finger ( 441 ) that extends substantially horizontal to form a C-shape with said external runner ( 320 ) 
   
   
       17 . The apparatus of  claim 16 , wherein said external runner ( 320 ) is about 11.5 inches, and said arm ( 442 ) is about 1.75 inches, and said finger ( 441 ) is about 1 inch.