RELATIONSHIP TO OTHER APPLICATIONS 
       [0001]    This application is a divisional application of U.S. application Ser. No. 13/438,575, filed Apr. 3, 2012, which application is incorporated by reference for all purposes and from which priority is claimed. 
     
    
     BACKGROUND 
       [0002]    Residential wooden stairs are usually purchased as a prefabricated unit with the risers (vertical elements) and the treads (horizontal elements) fastened to stringers in their final form. In the prior art, these prefabricated staircases are installed in, for example a home construction, and construction on a home continues with workmen walking up and down the staircase to perform their construction tasks. Even if the treads (the horizontal surfaces) are covered with a protective material, they can suffer damage during the construction process. 
         [0003]    After all major construction in the home is completed, workmen must come in and finish the staircase by sanding the treads and risers and applying appropriate finish coatings to them. If the risers and treads are damaged in any way because of months of foot traffic, the refinishing process takes longer and is more expensive. 
       BRIEF SUMMARY 
       [0004]    Embodiments of the invention to be searched avoid the problem by installing a prefabricated staircase where the risers and treads are not the final materials to be used. Rather the tread is a “sub-tread” and the riser is a “sub-riser” meaning that another surface will be applied on top of the sub-tread and sub-riser in order to finish the staircase. 
         [0005]    The present invention solves prior art problems by creating a prefabricated staircase that is “double routed” to allow an initial set of sub-treads and sub-risers to be installed. The purpose of the double routing is to provide additional space for a final capping tread and riser to be installed by inserting the capping riser or tread in the routed space. This provides for a simpler installation process where little to no cutting and or fitting of the final treads and risers (referred to herein as “capping treads” and “capping risers”) is required. 
         [0006]    The double routing is made to a depth that permits a capping tread or riser to be inserted into the routed space and shifted to the right or left in a small amount so that the tread remains in the routed space on either side of the staircase. This allows for a finished look without having to butt the final tread and riser up against the side of the stringer that is secured to the sub-risers and sub-treads. Once the capping riser and/or capping tread is in place, it is secured to the sub-riser or sub-tread (as appropriate) via adhesive or mechanical means (or both) known in the art. 
         [0007]    This has several advantages. First, a fully functional staircase is installed so that workmen can proceed with finishing the home or structure without having to worry about whether the finished treads or finished risers are being damaged 
         [0008]    Second the owner can decide what finish and material to apply to the final tread or riser that is applied over the sub-tread or sub-riser and those capping risers and treads can simply be installed over the sub-tread and sub-riser after all major construction is completed thereby avoid any potential for damage to the capping risers and treads while keeping the stair compliant with appropriate building codes. Other advantages of the various embodiments disclosed herein will be apparent to those of ordinary skill in the art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  illustrates a Closed stringer routing used on Boxed and Single Open staircase designs of an embodiment; 
           [0010]      FIG. 2  illustrates a finished installation of treads and risers into a double routed stringer; 
           [0011]      FIG. 3  illustrates a view of an embodiment having a sub-tread installed in stringers; 
           [0012]      FIG. 4  illustrates a view of an embodiment having sub-tread and capping tread installed in stringers; 
           [0013]      FIG. 5  illustrates an enlarged view of the finished installation of sub-tread and sub-riser; 
           [0014]      FIG. 6  illustrates the final installation of a sub-riser and the capping riser; 
           [0015]      FIG. 7  illustrates a side view of an embodiment of an assembled staircase; 
           [0016]      FIG. 8  illustrates an embodiment of the routing for sub-risers and sub-treads; 
           [0017]      FIG. 9  illustrates an embodiment of the open riser and tread layout; and, 
           [0018]      FIG. 10  illustrates an embodiment of a staircase having the double routed channels of differing depths. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    Referring now to  FIG. 1  a closed stringer routing embodiment is illustrated. The stringer  102  forms the main support for a set of stairs. A stringer is the long piece that the stair treads and risers attach to on either side, and which goes diagonally up the wall. In an embodiment, stringer  102  comprises a double-routed channel shown generally as  104 . The double routed space comprises a routed channel wide enough to support a tread and sub-tread (in the horizontal orientation), and a riser and sub-riser (in the vertical orientation) and as further illustrated in  FIG. 2  below). The double-routed channel  104  comprises a sub-tread  106  and sub-riser  108  routing areas. Note in this  FIG. 1  the illustration is to the routed area. In addition, the double-routed channel  104  further comprises a routing space for a capping tread  110  and a routed space for a capping riser  112 . Additionally, the double-routed channel  104  also comprises sufficient room for the insertion of wedge blocks that, in an embodiment, support the sub-tread and sub-riser. These wedge blocks will be discussed below. The double routed spaces are located on the stringer at varying and in some cases uneven locations that eventually provides for the capping treads and risers to be positioned in the staircase such that applicable building codes are met. Double routing as illustrated herein is accomplished using a model CSR-750CNC Stair Router available from US Concepts although this is not meant as a limitation. Other CNC routers may also be appropriate for the double routing illustrated herein. 
         [0020]      FIG. 2  illustrates a finished installation of treads and risers into a double routed stringer. The double-routed channel ( FIG. 1 ,  104 ) is illustrated together with a sub-riser  202 , a sub-tread  204 , a capping riser  206 , a capping tread  208 , sub-tread wedge blocking  210  and a sub-riser wedge blocking  212 . 
         [0021]    In normal practice of an embodiment, a staircase is constructed using 2 stringers, each of which has double routed channel ( FIG. 1 ,  104 ) for risers, sub-risers, treads and sub-treads. However, the staircase is initially constructed as a prefabricated staircase or as a staircase kit which can be field assembled into a unit comprising double routed channels and sub-treads and sub-risers. The application of capping treads and risers occurs later as discussed below. 
         [0022]      FIG. 3  illustrates the installation of a sub-tread  302  in stringers  102 A and  102 B. Double-routed channel  104  allows sub-tread  302  to be recessed and secured into each stringer,  102 A and  102 B. Because the double-routed channel  104  is double routed, there is sufficient room left for the placement of a capping tread. Channel spaces for capping treads are illustrated as  304  and  306 . During construction of the staircase, multiple sub-treads are secured into the stringers  102 A, and  102 B in as many steps as necessary to span a particular vertical distance. For purposes of this Figure, a single sub-tread is illustrated. 
         [0023]      FIG. 4  illustrates the installation of the capping tread. Once the sub-treads  302  and stringers  102 A and  102 B are assembled, the installation of a capping tread can occur. The capping tread  402  is cut to a length that is less than the full length of sub-tread  302 . This allows the capping tread  402  to be inserted into the remaining open section of the double -routed channel  304 . Because the capping tread is shorter than the full length of sub-tread  302  it can be inserted fully into the double-routed channel for capping-tread  304  to house the capping tread lowered into place and then shifted laterally so that the capping tread is surrounded by and contained in the double routed capping tread channel yet still is embedded in stringers  102 A and  102 B. The capping tread  402  can then be secured to sub-tread  302  with adhesives or fasteners known in the art. 
         [0024]      FIG. 5  illustrates an enlarged detail of the final installation of the capping tread  402  and sub-tread  302 . In this illustration stringer  102 A is shown with the double-routed channel  304  (illustrated in phantom) with sub-tread  302  installed into stringer  102 A. Capping tread  402  is shown in its final position where it has been initially inserted into double-routed channel  304  and moved laterally to fit partially into double-routed channel  304  of stringer  102 A and double-routed channel  306  of stringer  102 B (not shown). While this leaves a slight unfilled portion  406  of double routed channel  304 , the capping tread  402  is still completely embedded in and surrounded by stringer  102 A and similarly in stringer  102 B. 
         [0025]      FIG. 6  illustrates the final installation of a sub-riser and the capping riser. In this Figure, sub-riser  602  is installed in stringer  102 A in the same manner described above with respect to the sub-treads. Once the staircase is fully fabricated with sub-risers and sub-treads, capping risers and capping treads can be installed. As illustrated in  FIG. 6  sub-riser  602  is installed in double routed riser channel  604 . Sub riser  602  is illustrated in horizontal hatching. Capping riser  603  can then be inserted into double routed riser channel  604  and then moved laterally to engage a similar channel in stringer  102 A. Thus, while capping riser  603  does not fully occupy double-routed riser channel  604  it is still surrounded by stringer  102 A and similarly on the opposite side is surrounded by stringer  102 B (not shown). 
         [0026]      FIG. 7  illustrates a side view of the assembled staircase of an embodiment. In this embodiment, sub-tread  702  is in place in the double routed tread channel. A capping tread  704  is installed in the double routed tread channel over the top of sub-tread  702  and the combination of sub-tread  702  and capping tread  704  is held in place by tread wedge blocking  712 . Similarly, sub-riser  706  is in place in the double routed channel with capping risers  708  installed on top of sub-riser  706 . The combination of sub-riser  706  and capping riser  708  are held in place by sub-riser wedge block  710 . 
         [0027]      FIG. 8  illustrates the routing for sub-risers and sub-treads. Routing channel for sub-riser  806  is illustrated together with the routing channel for capping riser routing channel  802 . Similarly the sub-tread routing  808  is illustrated together with the capping tread routing channel  804 . It should be noted that while capping tread routing channel  804  is shown with a “bullnose” design, this is merely a design choice. The capping tread routing channel  804  may have other edge designs that equally fall within the scope of the various embodiments illustrated herein. 
         [0028]    In an embodiment, the first riser of a staircase of the various embodiments illustrated herein will be shorter than other risers in the staircase by an amount equal to the thickness of the first capping tread. That thickness of the capping tread will add to the height of the first step. In order to have all steps of a similar height, it is therefore necessary to have the first riser of the staircase be shorter by the same amount as the thickness of the first capping tread. Thereafter, all riser heights will be the same for subsequent steps in the staircase. 
         [0029]    It should be noted that multiple configurations of staircases falling within the various embodiments illustrated herein are possible. For example, and referring to  FIG. 9  an open riser and tread layout is illustrated. In this case the floor level stair stringer is set on floor level  906 . However the first sub-riser height  902  will be will be shorter by the same amount as the thickness of the capping tread. Thus for example, and without limitation, in a sample staircase the first riser height would be 7⅜ inches. All successive sub-riser heights  904  will be 8 inches in height. When the first riser  902  has a ⅝ inch thick oak tread installed at the top of the riser, this will make that riser height 8 inches. Thus each step will have the same height. In this fashion the “first staircase step” height will be the combination of the first riser height plus the thickness of the first sub-tread, plus the thickness of the first capping tread. 
         [0030]    Referring now to  FIG. 10 , a staircase is illustrated having the double routing channels of differing depths. In this embodiment, stringer  1002  comprises double routed channels for sub-treads, sub-risers capping treads and capping risers. It should be noted that it is not a requirement that the depth of the routed channels be the same. For example sub-riser channel  1008  may, in an embodiment, be ½ inch deep. Similarly the sub-tread channel  1010  may also be ½ inch deep. However in this embodiment, the capping riser channel  1006  may only be ¼ inch deep. Similarly the capping tread channel  1004  may also be only ¼ inch deep. Other combinations of channel depths are also considered to be within the scope of the various embodiments disclosed herein. 
         [0031]    A method for creating and building a staircase has been described. It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the scope of the invention disclosed and that the examples and embodiments described herein are in all respects illustrative and not restrictive. Those skilled in the art of the embodiments illustrated herein will recognize that other embodiments using the concepts described herein are also possible. Further, any reference to claim elements in the singular, for example, using the articles “a,” “an,” or “the” is not to be construed as limiting the element to the singular.
A staircase and method for producing the same. The staircase is produced by double routing channels for sub-treads and sub-risers and capping risers and capping treads. These sub-treads and sub-risers are assembled into staircase stringers that have pre-routed channels that are sufficient to install sub-treads and sub-risers having a particular thickness and having room for subsequent placement or installation of capping treads and risers by sliding them laterally into the channels created by the double routing of the stringers. This creates a more finished look to be (the) staircase while avoiding damages to the capping treads and risers that might occur during building construction.