Patent Publication Number: US-6665987-B2

Title: Staircase, staircase repair device and methods of fabricating same

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of U.S. patent application Ser. No. 09/311,526, filed May 13, 1999, is now U.S. Pat. No. 6,318,033 which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a staircase and a staircase repair device adapted to be used for both residential and commercial buildings and, more particularly, to a staircase including specially constructed stair tread members for use with standard stringers, and a staircase repair device or kit which can refurbish an existing staircase in need of repair without modification of the original staircase. Methods are also provided for fabrication. 
     BACKGROUND ART 
     A number of prior art devices exist which relate to the construction of a staircase, or the repair or refurbishing of a staircase. Particularly for conventional outside stairs and emergency stairs in both residential and commercial applications, such stairs are often constructed of materials which do not withstand heavy traffic or harsh environmental conditions. Because of safety concerns, stairs should always be kept in a high state of maintenance. However, the cost to repair damaged staircases can be quite prohibitive, even for minor flaws. For example, stairs formed of concrete which have chips or other surface defects are not only dangerous, but are also unsightly. Concrete repair is usually a very temporary measure and, particularly in high traffic areas, the concrete repair is never as wear-resistant as the original concrete. For wooden stairs, the wood has a tendency to warp or deform along heavy traffic areas. Even if constructed of treated lumber, the wood becomes unsightly over time. 
     There are a number of examples of prior art devices which have attempted to overcome one or more of the following problems. These devices can be in the form of either a repair unit, or a complete staircase construction. 
     U.S. Pat. No. 5,357,724 discloses a stair tread in which rubber sheet material is placed around a metal core section, and then heated to melt the sheets together. Once heated, the core section is encapsulated within the rubber. The stair tread has anti-slip serrations formed on its upper surface. A front face or overhanging front lip forms the front edge of the stair tread, and a vertically extending rear flange forms the rear face or edge of the stair tread. The upper edge of the rear face has a groove to accept the lower edge of a riser board, while the upper edge of the riser board is inserted into a corresponding groove formed in the lower edge of the front face of the next higher stair tread. 
     U.S. Pat. No. 5,799,448 discloses an adjustable closed riser metal staircase system. The system includes a plurality of stair treads which may be assembled into staircases having different rise heights. The stair treads include a vertical riser portion and a horizontal walking surface, preferably made of a slip-resistant material such as Mebac™, a coating of thermally sprayed steel encapsulating a dispersion of grit materials, normally aluminum oxide. The nose piece portion of the stair tread is formed at the front of the stair by bending the forward edge of the steel plate downward. When assembled, the upper end of the riser portion is inserted within a channel created by the bent nosepiece of the next higher stair tread assembly. 
     U.S. Pat. No. 4,783,939 discloses a composite covering for improving worn out treadways of steps. This covering includes a stair tread section which is placed over the existing stair tread, and an integral vertical flange which overhangs the front lip of the stair tread section. The covering is constructed of a scuff-resistant plastic. The underside of the stair tread section includes an insert of pressboard, and a binder which helps raise the elevation of worn out sections or indentations, and also serves to bind the layers of the composite covering. 
     U.S. Pat. No. 5,660,009 discloses a metal stairway construction in which stair steps are supported between a pair of trimmed sheet metal stringer panels on each side of the stairway. Each step of the stairway is formed of metal treads and risers cut to appropriate lengths from conventional joice members provided on site. The metal treads and risers are attached at opposite ends thereof to respective stringer panels by way of standard angle brackets. Threaded self-drilling fasteners attach each angle bracket to a corresponding stringer panel and to an associated metal tread or metal riser. Wooden treads and risers are attached over the corresponding metal treads and risers by standard self-drilling screws. 
     While the foregoing references may be adequate for their intended purposes, there are certain advantages with the present invention which are not found in these references. One advantage is that the staircase repair device of this invention can be used with any type of existing staircase, whether it be concrete, wood, or metal. Another advantage is that this staircase repair device can be used to repair a staircase without preparation or modification of the original staircase wear surfaces. Yet another advantage not overcome by the prior art is the use of a staircase repair device which has high strength and weathering capabilities, yet does not detract from the general aesthetic appearance of the staircase. The same advantages discussed above also apply to the staircase of this invention. Additionally, the staircase of this invention is simple in design, and can be used for stairways in a wide array of residential and commercial buildings. 
     DISCLOSURE OF THE INVENTION 
     In accordance with this invention, a staircase and a staircase repair device or kit are provided. The staircase repair device or kit forms a first embodiment and is comprised of two major components, namely, a stair tread repair member and a riser repair member. Both of these members are constructed of metal, preferably raw steel, bent to desired shapes. The stair tread repair member includes a front flange and an inward protruding lip. Holes may be drilled in the wearing surface of the stair tread repair member in order to accept fasteners which help to secure the stair tread repair member to an existing stair tread. The riser repair member includes an outward protruding flange. Holes may also be drilled in the riser repair member to accept fasteners for attachment of the riser repair member to an existing staircase riser. Both the stair tread and riser repair members are coated with a synthetic material which protects the metal from corrosion and other environmental hazards. The coating is preferably in the form of a polyurea or polyurethane which is sprayed in liquid form to encapsulate the members therein. The upper wearing surface of the stair tread repair member also has a slip-free surface. This slip-free surface is formed by particles which are spread or sprinkled over the first sprayed coating of synthetic material. These particles are spread on the first coating while it is wet which allows the particles to become embedded in the first coating. Then, a second coating of synthetic material is sprayed over the embedded particles to seal the particles between the first and second coatings. The particles may be materials such as coal dust, aluminum oxide, walnut shells, and other known granular-type material which is used to create slip-free surfaces. It shall be understood that the stair tread repair member serves as a subcombination which may be used to repair the stair treads of an existing staircase. 
     In a second embodiment, the invention is a staircase which includes a plurality of stair tread members which span between a pair of spaced stringers. The stair tread member is similar to the stair tread repair member of the first embodiment in that it is also constructed of metal bent to a desired shape encapsulated within a first coating of synthetic material, and having a slip-free surface made of a particulate material sandwiched between the first coating and a second applied coating. The stair tread member further includes a pair of opposed side flanges disposed on opposite ends of the stair tread member, and opposing front and rear flanges. The stair tread member spans between a pair of common stringers used in construction of staircases. The stair tread member may be mounted to the facing inner surfaces of the stringers, or may be mounted over the outer surfaces of the stringers. Optionally, an L bracket or other similar supporting hardware may be used to secure the stair tread member to the inner surfaces of the stringers. 
     The second embodiment may be used in conjunction with either metal or wood stringers. Holes are drilled in the side flanges for receiving fasteners which secure the stair tread member to the stringers. If desired, a riser member could also be used with the invention of the second embodiment. More specifically, a riser similar to the riser repair member of the first embodiment could be used in the second embodiment. The riser in the second embodiment could simply be rectangular in shape and coated in the same way as the other components. 
     Methods of fabricating a stair tread repair member and of fabricating a stair tread member in a new staircase are also provided. Both methods involve the provision of a flat sheet of metal cut to a desired size. The metal sheet is sanded to roughen its surfaces in preparation for coating with a synthetic material. A primer may be applied to further prepare the metal sheet for coating. The metal sheet is bent by a metal brake machine to the desired shape. In fabrication of the stair tread repair member, the sheet is bent to form the front flange and inward protruding lip. For the stair tread member of a new staircase, the sheet is bent to include front and rear flanges, and the opposed side flanges. In order to bend the sheet of metal used in the stair tread member, corner sections are removed. After the sheet has been bent, the joints formed at the corners of the stair tread members may be welded together. Prior to or after bending, screw holes are punched or drilled in the metal sheets enabling fasteners to be received therethrough. 
     Once the stair tread repair member and the stair tread member have been bent to the desired shapes, they may be sprayed with a synthetic coating, preferably the polyurea or polyurethane. This coating can be applied to all exposed surfaces. The coating of the members helps to ensure that all surfaces are protected from corrosion and other environmental hazards. The upper wearing surfaces of the members are then sprinkled with a dispersed layer of particles. This preferably occurs when the first applied coating is still wet which enables the particles to become embedded within the first coating. A second coating is then applied over the dispersed layer of particles to encapsulate the particles between the first and second coatings. A slip-free surface is therefore formed by the second coating covering the particles. In addition to providing weather-resistant surfaces, the coatings of polyurea or polyurethane also help to dampen noise normally associated with metal stair treads, and help to keep the wearing surfaces scuff-free. Additionally, the applied coating may be mixed with a desired color which enables the components to match or complement existing colors on the building. For the staircase embodiment, the stair tread members may include diagonal stress lines pressed on the upper wearing surfaces. This pre-stressing of the upper wearing surfaces adds strength to resist any buckling or wobbling of the upper wearing surfaces. 
     The apparatuses and methods of this invention provide a staircase repair device and a staircase which are extremely durable, simple in construction, aesthetically pleasing, have integral slip-free surfaces, and resist scuffing. Furthermore, these devices are simple to install and are universal in their ability to be used for all types of buildings. 
     Additional advantages of this invention will become apparent from the description which follows, taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a stair tread repair member of the first embodiment; 
     FIG. 2 is a perspective view of a riser repair member of the first embodiment; 
     FIG. 3 is a fragmentary perspective view of the staircase repair device of the first embodiment mounted to an existing staircase or stairway; 
     FIG. 4 is an enlarged vertical section, taken along line  4 — 4  of FIG. 3 illustrating one manner in which the first embodiment may be mounted to the existing staircase; 
     FIG. 5 is an enlarged vertical section taken along line  5 — 5  of FIG. 3 illustrating further details on the mounting of the first embodiment to the existing staircase; 
     FIG. 6 is an enlarged vertical section taken along line  6 — 6  of FIG. 3 illustrating yet further details on the mounting of the first embodiment to the existing staircase; 
     FIG. 7 is an enlarged fragmentary cross section of the stair tread repair member in FIG. 3 which illustrates a core metal layer, a first applied coating of synthetic material encapsulating the core metal layer, a dispersed layer of particles applied on the upper wearing surface, and a second coating placed on the dispersed layer of particles and trapping them between the first and second coatings; 
     FIG. 8 is a perspective view of a stair tread member of the second embodiment; 
     FIG. 9 is a perspective view of the stair tread member of FIG. 8 prior to being bent into the desired shape; 
     FIG. 10 is a fragmentary perspective view of the staircase construction of the second embodiment illustrating stair tread repair members being mounted to stringers in three different manners; 
     FIG. 11 is an enlarged fragmentary perspective view of FIG. 10 illustrating details of how a stair tread member is mounted over the stringer; 
     FIG. 12 is an enlarged fragmentary vertical section taken along line  12 — 12  of FIG. 10 illustrating details of how a stair tread member may be mounted to the inner surfaces of the stringers; and 
     FIG. 13 is another enlarged fragmentary vertical section taken along line  13 — 13  of FIG. 10 illustrating another manner in which a stair tread member may be mounted to the inner surfaces of the stringers. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     According to a first embodiment, a stair case repair device is shown in FIGS. 1 and 2 which comprises a stair tread repair member  10  and a riser repair member  12 . The stair tread repair member  10  has a wearing surface  14 , and a front flange  16  extending from the forward or front edge of the wearing surface  14 . Contiguous with the front flange  16  is an inward protruding lip  18 . A plurality of holes  19  may be drilled through the wearing surface  14  to receive fasteners. The riser repair member in FIG. 2 has a riser surface  20  and an outwardly protruding flange  22 . A plurality of holes  23  may be drilled in both riser surface  20  and flange  22  to receive fasteners. 
     FIG. 3 illustrates the staircase repair device installed on an existing stairway or staircase. As shown, the existing stairway has a plurality of stair treads  26  which are mounted between a pair of stringers  24 . A plurality of vertical risers  28  are also mounted between the stringers  24 . The top of the stairway leads to a landing  30  which communicates with a doorway  32 . 
     FIG. 4 illustrates in further detail the manner in which stair tread repair members  10  and riser repair members  12  are secured to the staircase. As shown, fasteners  38  may be placed through holes  19  and  23 , respectively. Additionally, an appropriate industrial adhesive or cement (not shown) may be used to secure members  10  and  12  to respective stair treads  26  and risers  28 . FIG. 4 illustrates wearing surface  14 , front flange  16 , and lip  18  closely conforming to the lip  27  of the stair tread  26 . However, it will understood that front flange  16  and lip  18  function equally as well even if there is some gap which exists between these members and the exterior surfaces of lip  27 . Also, the size and shape of front flange  16  and lip  18  may be modified to fit the particular type of staircase encountered. As further shown in FIG. 4, the upper edge of riser surface  20  extends very nearly to or in contact with the edge of lip  18 . It should also be understood that riser repair member  12  functions equally as well even if there is some gap between lip  18  and riser surface  20 . 
     As shown in FIG. 5, the edge of flange  22  is placed underneath the rear edge of wearing surface  14 . Fasteners  38  may also be used to secure the members to each other and to stair tread  26  at this location. 
     As shown in FIG. 6, the landing  30  may be repaired by the use of landing repair member  39 . Landing repair member  39  may also be used to provide continuity with the covered stairway even if the landing is not damaged. The landing repair member  39  may be secured to the landing  30  by means of adhesive/cement, and/or by a plurality of fasteners  38  extending through landing member  30  and the edge of wearing surface  14 . 
     FIG. 7 more specifically shows a cross section of materials used to construct the stair tread repair member  10 . A steel layer  40  is encapsulated within a first layer or coating of synthetic material  42 . Preferably, this coating is polyurea or polyurethane which is sprayed directly onto the steel layer  40 . As shown, this layer covers both the upper surface and the lower surface. A dispersed layer of particles  44  is then sprinkled over the first layer  42 . If the first layer  42  is wet when the layer of particles  44  is applied, the particles  44  will be embedded within the first layer  42  as shown. However, it will be understood that the dispersed layer of particles  44  may be applied after the first layer  42  has been allowed to dry. A second layer of coating is applied over the dispersed layer of particles  44  trapping or encapsulating them between the first and second layers. Thus, the upper surface of the stair tread repair member  10  has an undulating or rough surface which is slip-free. The coating used is extremely wear-resistant and serves not only to protect the steel core, but also to provide a bonding and scaling agent for the dispersed layer of particles  44 . The riser repair member  12  is also coated with a layer of polyurea or polyurethane; however, no slip-free surface is required so no layer of particles or second layer of coating is applied. Landing repair member  39  may be made of the same composite construction as stair tread repair member  10 . 
     Although the first embodiment illustrates the use of both stair tread repair members and riser repair members, it shall be understood that the stair tread repair members alone can be used to repair damaged staircases when such staircases have or do not have risers. Since risers are not wearing surfaces, a more cost-effective repair can be completed without the use of the riser repair members. Thus, the stair tread repair members serve as a valuable subcombination of the first embodiment. 
     FIG. 10 illustrates the second embodiment of this invention which is a stairway or staircase. This staircase includes two primary members, namely, a plurality of stair tread members  50 , and a pair of opposed stringers  68 . Beginning first with a discussion of the stair tread members  50 , one of which is shown in FIG. 8, each includes a wearing surface  52 , a front flange  54 , a rear flange  56 , and a pair of opposed side flanges  58 . A pair of diagonally opposed stress lines  60  may be formed on the wearing surface  52  to add bending strength. A plurality of holes  62  may be drilled in side flanges  58  in order to receive fasteners, as further discussed below. 
     FIG. 9 illustrates a stair tread member  50  prior to being bent into shape. Comer sections  64  are removed which enable the sheet of material to be bent along bend lines  66 . Bending may be achieved by a standard metal break machine. Preferably, holes  62  are drilled prior to bending the member  50  into shape. Stress lines  60  are also formed during the metal break operation. Thus, it is clear that stair tread members  50  may be formed simply from rectangular sheets of metal. After bending, corners  67  may secured as by welding, or other well known means. 
     FIG. 10 illustrates the staircase assembled, and further shows three ways in which stair tread members  50  may be mounted to the pair of stringers  68 . Stringers  68  may be of any well-known construction to include cut pieces of lumber, or cut pieces of heavy gauge metal. The stringers  68  each have inner surfaces  70 , outer surfaces  72 , and upper surfaces defined by a plurality of continuous rises  74  and runs  76 . The details of how the most upper stair tread member  50  attaches to the stringers  68  is shown in FIG.  11 . In this case, the stair tread member  50  is mounted over the outside surfaces  72  of stringers  68 . Side flanges  58  are placed over outer surfaces  72 . In order to allow the stair tread member  50  to fit over runs  76 , slots are cut out of the rear flange  56  near the rear corners at least a width as wide as the width of run  76 . In FIG. 11, the width of the slot removed is shown as width  78 . As needed, fasteners  79  are then used to secure the stair tread member  50 . 
     An alternate manner in which to mount a stair tread member  50  to the stringers  68  is through an inside mount. This is shown in FIG. 12 wherein side flanges  58  are secured to the inner surfaces  70  of stringers  68 . Fasteners  79  may also be used to secure the connection. Thus, the method shown in FIG. 12 requires the stair tread member  50  to be slightly shorter in length to accommodate the smaller gap between the inner surfaces  70  of the opposed stringers  68 . 
     FIG. 13 shows yet another manner in which the stair tread members  50  may be secured to the stringers  68 . As shown, this is also an inside mount, but further includes the use of L-shaped brackets  80  which help to stabilize the connection. As shown, L brackets  80  are placed between side flanges  58  and inner surfaces  70 . Fasteners  79  may also be used to secure the connection. 
     Although FIG. 10 does not illustrate the use of risers, it shall be understood that risers can also be used. Riser repair member  12  of the first embodiment may be modified to simply eliminate flange  22 , resulting in a rectangular shaped member. This rectangular shaped member may be sized to fit the particular rise  74 , and then secured thereto, either by fastener  79  or adhesive. Stair tread members  50  are made of the same composite construction shown in FIG.  7 . If risers are used in this second embodiment, then they can be coated in the same manner as the riser repair members  12  of the first embodiment. 
     Both the first and second embodiments illustrate staircases with risers that include continuous rises and runs. However, it shall be clearly understood that both the first and second embodiments can be used with any type of stringers to include those which do not have continuous rises and runs, but have continuous flat upper surfaces. For these types of stringers, the stair tread members of the second embodiment must utilize an inside mount. 
     In practice, it has been found that stair tread repair members  10  and stair tread members  50  can be made of 18 gauge metal which provide adequate strength to resist undue deformation or bending. It has also been found that riser repair members  12  may be made of a thinner gauge steel, such as 24 gauge. In heavy traffic areas, it has also been found that 16 gauge metal is acceptable for stair tread members  50 . Examples of commercially available polyurethane spray coatings which may be used with this invention include Bullhide™ manufactured by Bullhide, Inc. 
     It should also be understood that the dispersed layer of particles could be applied as a mixture with the coating spray. That is, particularly for smaller sized particles, a combination of the polyurea or polyurethane and the particles could be sprayed simultaneously as a composite coating. The polyurea/polyurethane and particles can be premixed in a hopper, and then can be sprayed from a standard commercial spray gun. Furthermore, it should be understood that a single layer of coating can be utilized without a second covering or coating. Depending upon the thickness of the first coating, it may only be necessary to apply a single coating wherein the dispersed layer of particles are adequately held within the single coating. 
     Although a dispersed layer of particles is advantageous for use in providing a slip-free surface, the coating of synthetic material itself may provide enough friction as compared to the existing staircase; therefore, the dispersed layer of particles does not have to be applied. 
     The specific amount of coatings applied to the components may vary as desired. In practice, it has been found that the lower surfaces of the components are adequately covered with a 60 mil covering, and the upper surfaces are adequately covered with an 80 mil coating. For the second coating applied over the dispersed layer of particles, 40 mils has been found to be adequate. The polyurethane spray will adequately dry and cure by air drying. No heat treatment is required; however, drying time can be shortened by use of heat lamps or other heating means. 
     For the first embodiment, there is no requirement that the wearing surfaces of the existing staircase be repaired or otherwise prepared. For example, damage to the stair treads in the form of holes or other imperfections do not have to be filled prior to installing the invention. Because the invention includes continuous sheets of high strength material, they are able to cover imperfections in the underlying surfaces yet provide the desired walking or wear surfaces. Of course, if the existing staircase is structurally unstable, it must be repaired prior to installing the invention. 
     One clear advantage of the invention is the simplicity of its construction. The components making up each of the embodiments are simply bent sheets of metal encapsulated within a synthetic coating. An integral slip-free tread surface is formed directly on the first coating. The invention may also be adapted for use with literally any type of staircase or stairway requirement. Each of the components may be sized and bent to specifications without altering the general principles of the invention. 
     Furthermore, the invention can be constructed with relatively simple machinery and processes. A standard metal break machine may be used to bend the components to desired shapes. Polyurea or polyurethane as a spray coating is readily available and can be applied with standard industrial sprayers. Since no heat treating is required, the coatings may simply air dry. Any number of differing types of particles may be used to create the slip-free wearing surfaces. Depending upon the application, the particles may be applied in a mixture, or by themselves in a homogenous layer. Yet another advantage of this invention is the ease with which it is installed. Standard fasteners such as screws or bolts are used to assemble the components, along with adhesive or glue, as necessary. No special tools are required for assembly, and the components are easily shipped and stored. 
     This invention has been described in detail with reference to particular embodiments thereof, but it will be understood that various other modifications can be effected within the spirit and scope of this invention.