A construction site staircase assembly and installation method therefor

Abstract

A prefabricated staircase assembly of different modules for assembling on a construction site of a building between upper and lower floors, and method of assembling thereof. The modular staircase assembly includes staircase modules with stringers and treads mounted on and supported by posts extending between the floors. A stairwell frame or module attaches to a stairwell extending through the upper floor and connects to the posts. A railing assembly or module mounts on the stairwell frame before being replaced by the walls of the stairwell. All parts of modules of the staircase assembly are fabricated and adjusted in factory before shipment and installation on site.

1 . A staircase assembly for assembling on a construction site of a building between upper and lower floors, the upper floor having an opening extending therethrough and defining a stairwell, the staircase assembly comprising:
 a plurality of posts extending between the upper and lower floors and being connected thereto;   stringer anchors attaching to at least two of the plurality of posts;   two stringers positioned parallel to and spaced from each other, at least one of the two stringers mounting on the stringer anchors;   a plurality of treads equally spaced from one another and positioned along the two stringers; each said tread defining a rear side attaching to the two stringers via a respective rear tread attachment and a front side securably connecting to the rear side of a frontward adjacent one said tread via a front tread attachment;   for each said tread, the rear tread attachment being slidably adjustably positioned along the two stringers and allowing angular pivoting adjustment of the tread relative to the two stringers about a pivoting axis generally perpendicular to the two stringers; and   for at least each said tread but a frontward most said tread, the front tread attachment being adjustable in length to allow adjustment of a height between the two adjacent said treads connected thereto thereby ensuring a horizontal levelling of the tread.   
     
     
         2 . The staircase assembly of  claim 1 , further including a stairwell frame adapted to be installed on the upper floor at a perimeter of the stairwell, the stairwell frame including a plurality of stairwell beams positioned in an end-to-end configuration along the perimeter, at least one said stairwell beam having a lower ledger strip facing downward toward the lower floor mounted there under, at least one said post connecting to the lower ledger strip. 
     
     
         3 . The staircase assembly of  claim 2 , wherein the lower ledger strip includes a lower channel extending there along to allow for a lengthwise adjustable positioning of the at least one said post there along. 
     
     
         4 . The staircase assembly of  claim 2 , further including a railing assembly having railing posts supporting a railing handrail, at least one said stairwell beam having an upper ledger strip facing upward opposite the lower ledger strip and away from the lower floor mounted thereon, the railing posts mounting on the upper ledger strip. 
     
     
         5 . The staircase assembly of  claim 4 , wherein the railing assembly further includes at least one transversal retaining bar mounting on at least two of the railing posts. 
     
     
         6 . The staircase assembly of  claim 4 , wherein the upper ledger strip includes an upper channel extending there along to allow for a lengthwise adjustable positioning of the railing posts there along. 
     
     
         7 . The staircase assembly of  claim 1 , wherein the at least one of the two stringers includes a plurality of transverse slots extending there through and generally parallel to one another, each said transverse slot receiving a respective stringer anchor therein. 
     
     
         8 . The staircase assembly of  claim 1 , wherein the at least one of the two stringers has a top portion slidably receiving the rear tread attachment of each said tread there along. 
     
     
         9 . The staircase assembly of  claim 8 , wherein the rear tread attachment includes a lower jaw body slidable along the top portion and clamping there onto at a predetermined position. 
     
     
         10 - 13 . (canceled) 
     
     
         14 . The staircase assembly of  claim 1 , further including an angle tread frame structure mounting on frame anchors attached to selected ones of the plurality of posts, and a plurality of angle treads mounting on the angle tread frame structure. 
     
     
         15 - 17 . (canceled) 
     
     
         18 . A method for assembling a staircase assembly on a construction site of a building between upper and lower floors, the upper floor having an opening extending therethrough and defining a stairwell, the method comprising the steps of:
 connecting a plurality of posts extending between the upper and lower floors to the upper and lower floors;   attaching stringer anchors to at least two of the plurality of posts;   positioning two stringers parallel to and spaced from each other, and mounting at least one of the two stringers on the stringer anchors; and   positioning a plurality of treads equally spaced from one another along the two stringers by attaching a rear side of each said tread to the two stringers via a respective rear tread attachment being slidably adjustably positioned along the two stringers and allowing angular pivoting adjustment of the tread relative to the two stringers about a pivoting axis generally perpendicular to the two stringers, and by securably connecting a front side of at least each said tread but a frontward most said tread to the rear side of a frontward adjacent one said tread via a front tread attachment being adjustable in length to allow adjustment of a height between the two adjacent said treads connected thereto thereby ensuring a horizontal levelling of the tread.   
     
     
         19 . The method of  claim 18 , wherein the step of connecting a plurality of posts includes the steps of:
 installing a stairwell frame on the upper floor at a perimeter of the stairwell by positioning a plurality of stairwell beams of the stairwell frame in an end-to-end configuration along the perimeter; and   connecting at least one said post to a lower ledger strip facing downward toward the lower floor and mounted under at least one said stairwell beam.   
     
     
         20 . The method of  claim 19 , wherein the step of connecting at least one said post includes the step of:
 connecting the at least one said post to the lower ledger strip by adjustably positioning the at least one said post lengthwise along a lower channel extending along the lower ledger strip.   
     
     
         21 . The method of  claim 19 , further including the steps of:
 mounting railing posts of a railing assembly on an upper ledger strip facing upward opposite the lower ledger strip and away from the lower floor and mounted on at least one said stairwell beam; and   mounting a railing handrail of the railing assembly on the railing posts.   
     
     
         22 . The method of claim  22 , wherein the step of mounting railing posts includes the step of:
 mounting the railing posts on the upper ledger strip by adjustably positioning the railing posts lengthwise along an upper channel extending along the upper ledger strip.   
     
     
         23 . The method of  claim 21 , further including the step of:
 mounting at least one transversal retaining bar of the railing assembly on at least two of the railing posts.   
     
     
         24 . The method of  claim 18 , further including the step of:
 mounting the at least one of the two stringers on the stringer anchors via transverse slots extending through the at least one of the two stringers and generally parallel to one another, each said transverse slot receiving a respective stringer anchor therein.   
     
     
         25 . The method of  claim 18 , further including the step of:
 slidably positioning the rear tread attachment of each said tread along a top portion of the at least one of the two stringers.   
     
     
         26 . The method of  claim 25 , further including the step of:
 clamping a lower jaw body of the rear tread attachment, being slidably positionable along the top portion, onto the at least one of the two stringers at a predetermined position.   
     
     
         27 - 28 . (canceled) 
     
     
         29 . The method of  claim 18 , further including the steps of:
 mounting an angle tread frame structure on frame anchors attached to selected ones of the plurality of posts; and   mounting a plurality of angle treads on the angle tread frame structure.   
     
     
         30 - 32 . (canceled)