The present invention is in the technical field of construction designs. More particularly, the present invention is in the technical field of stair case or stair box construction.
Traditionally, stair boxes for residential dwellings and commercial buildings have been built on site while a building is being constructed. To satisfy OSHA requirements and to complete construction, constructions crews have to provide a staircase for workers to access the upper floor(s). There are a number of solutions to this dilemma, with one of them being temporary stair boxes or stair cases built on site. However, temporary staircases tend to be unstable and unsafe. Using temporary stairs inevitably leads to other costs caused in particular by workplace injuries such as lost productivity, medical expenses and increased insurance premiums.
On the other hand, building better temporary stairs tends to waste time and resources. As a result, many builders install prefabricated stair boxes meant to be permanent, i.e., they are the stair boxes that will be in place when the construction is finished. Generally, the need and obligation for the stairs to be built arises early in the construction of a building or residence prior to the roof and walls being fully built. As a result, construction crews have traditionally been faced with a dilemma, namely, the stairs that are in place during construction are exposed to weather and the wear and tear of being used by the construction crews. However, the stair boxes need to have the appearance of being newly installed when the building is completed.
Prefabricated stair boxes have been on the market for years. Builders have the option of purchasing stair boxes that are already assembled and installing them into buildings as they are being built. Doing so saves them the time and trouble of building the stair box on site, but does nothing to solve the other problems presented by installing the stair box in the building before it is finished.
In their most basic form, prefabricated stair boxes are made of stringers, treads and risers. The stringers will have mortises1 or trenches cut into them with a trenching tool or machine. Generally there is one continuous mortise cut into one of the two surfaces of the stringer that is meant to engage with each of the risers and the treads; also, there is a rounded section of each tread portion of the mortise that is to accommodate the noses that are usually featured on each tread. If the finished stairs are meant to be covered with a species of hardwood or some other durable material other than carpet, that hardwood or other material is incorporated into or makes up the treads that are part of the stair box. More specifically, when the stair box is built, the pre-cut or prefabricated treads made of the desired material are installed in the box as the treads. The treads and risers are installed into the stair box by attaching them to the stringers usually by nailing them into place. Since the prefabricated treads usually vary a little bit in width, wedge shaped pieces of wood are wedged into place on the underside of the stair box to reduce any “play” or lateral movement in the finished stair box—particularly any lateral movement of the treads. The prefabricated stair box is further stabilized by wedging additional pieces of wood into place on the underside of the stair box between the risers and the treads. This configuration helps to reduce any squeaking noise the stairs may make when weight is applied to them. 1Mortise is used in this disclosure as a noun and a verb. When used as a noun, it refers to a groove or trench cut into a surface. When used as a verb it refers to the act of inserting a projected piece of wood or other material into such a trench or groove.
Using a prefabricated stair box creates a number of problems in addition to damage and wear and tear on the stair box caused by the construction crew use of the stairs during construction. For example, to the extent that the finished stair case is supposed to inlcude hardwood or a material other than carpet, the hardwood or other material has to be installed with the stair box well in advance of the rest of the home being completed. That brings up two more problems, first, the decorative material on the stairs has to match the flooring that is in other parts of the home, but must be picked out well in advance of the rest of the flooring being installed. Second, when sheet rock is installed and then painted, generally there is some damage or mess created that requires sanding and/or refinishing the exposed surfaces of the treads and risers after all the rest of the work is completed. Performing this work can increase the length of time it takes the job to be finished by as much as two or three days.
On the other hand, replacing the hardwood surface making up the treads or risers almost requires the complete disassembly of the stair box. The treads and risers are nailed and wedged into place as described above with no surface underneath them. When someone wants to remove the treads and risers, they have to pry them loose from the stringers to which they are attached after all of the wedges mentioned above are removed. Doing so generally damages not only the stair box itself, but the surrounding structures including walls and base boards.
Consequently, the traditional prefabricated stair box presents construction crews with a number of problems to solve. As a result, the inventor, having worked for years in the industry, has devised a stair box system that solves the above problems in a more economical manner while decreasing the amount of labor required to install the stair box.
The disclosed invention in its broadest form is a stair box system that is made of a core stair box that provides the structure of a stair box and is made of stringers, risers and treads. The core has certain unique features and provides a subfloor or core upon which to attach other parts of the system as described below.
The stair box core is formed by two stringers each with two surfaces—an inner surface that is meant to face the treads and risers and the opposite outer surface. Instead of a continuous mortise running the length of each stringer, common in conventional stairboxes, the inner surfaces of the stringers have a discontinuous series of mortises positioned to engage with the treads and not the risers. Each stair box core also includes a plurality of treads each having six (6) surfaces: a front surface, a back surface, a top surface, a bottom surface and two side surfaces. Similarly, each riser also has six (6) surfaces, namely a front surface, a back surface, a top surface, a bottom surface and two side surfaces. Moreover, each of the treads is beveled or tapered from the front to back surfaces, i.e. the front surface of each tread is a little bit wider than the back surface of each tread. Similarly, each of the risers is tapered or beveled in the similar manner—from the top surface to the bottom surface, i.e., the top surface is a little but wider than the bottom surface. During assembly of the stair box core, the treads are removably fixed to the stringers and then the risers are removably fixed to the treads using conventional fasteners, preferably screws. The treads are installed such that the narrower back surface of each tread is in contact with the narrower bottom surface of a riser. As a result, the stair box core is not completely “square” in that the width of the stair box at the front of the treads is greater than the width of the stair box at the back of the treads.
In additional embodiments of this system, each tread features one or more notches cut into its back surface and each riser includes a complementary hook cut into its bottom surface. However, a skilled artisan can appreciate that the structures could be reversed, i.e. the treads could feature hooks and the risers could feature notches. Regardless, when the risers and treads are assembled into the stair box core the treads are attached to the stringers after fitting their side surfaces into the mortises cut into the stringer's inner surfaces. As the risers are installed and attached to the treads, the hooks on the risers engage the notches on the treads. This arrangement has two basic advantages. First, it provides stability to the stair box and eliminates the need to place wedges or shims into or onto the bottom surface of the stair box to stabilize each step. Additionally, the hooks and notches form an open faced channel or groove on the underside of the stair box that can accept a separate structure. For example, in the best mode of this system, the inventor intends this channel to accommodate a separate piece of lumber or building material that can be used to facilitate attaching other structures, such as sheet rock, to the bottom of the stair box. Traditionally, sheet rock is simply nailed to the bottom of the stair box, but using a separate structure allows the builder to avoid nailing something into the underside of the stair box that could result in damage to the stair box during installation or removal.
Still further embodiments of this system include a plurality of removable covers configured to fit over the treads that are built as part of the stair box core. Each of these covers consists of a tread with six (6) surfaces, namely a front surface, a back surface, a top surface, a bottom surface and two side surfaces. In addition, the treads are also tapered or beveled from front to back making the front surface of the removable cover wider than the back surface. As a result of this tapering, the removable cover can be installed easily by sliding the cover over the surface of a tread that is part of the stair box—in doing so the fit between the stringers and the cover becomes tighter as the cover is slid in place over the tread. The removable covers are screwed into place for easy removal when the builder is ready to install finished hardwood or some other finished or decorative material onto the stair box. Similarly, the risers can be covered by a removable cover as well, but in fact the riser cover is not representative of the inventor's contemplated best mode.
In addition, these removable covers can be equipped with a nose. Typically, the treads of a stair box each feature a protrusion that extends past the point of contact between the top surface of the riser and the front surface of the tread. This protrusion is referred to as a nose and is generally a separate piece of wood or building material that is attached to the front surface of the tread. Because the nose is traditionally attached to the tread, it cannot withstand very much pressure placed directly on it without breaking loose, increasing the likelihood of a fall and damage to the tread. The inventor has taken advantage of the positioning of this structure to create a safety feature. The safety nose is a nose piece that is attached to the front surface of the tread portion of the removable cover via a mortised surface. The mortised surface reinforces the nose and makes it less likely to break off when pressure or weight is placed directly on it. The safety noses are ideally painted bright colors, such as orange, to make it easier to see the front surface or edge of each tread. This is especially important when the stair box is used in place of a temporary stair case in a building that is still under construction—the brightly colored nose helps construction crews spot the individual steps so that the surfaces of each step or stair do not visually appear to blend into each other. Such a feature tends to decrease the chances of a construction worker missing a step on the stair case and falling.
When construction is nearing completion, and the finish work has been completed, these removable covers can be removed to allow for the placement of the final finished surface. Alternately, carpet can be installed over the treads and risers of the stair box. If a non-carpeted surface is desired, the removable covers are removed and replaced with covers that are made entirely or partially of the desired finished material. For example, the final treads can be made of a finished hardwood or can feature a hardwood veneer. Similarly the final risers can be made entirely of or partially of a hardwood or other desired material. In preferred embodiments, the treads and/or risers are made of a medium density fiberboard with one or more surfaces covered with a decorative material such as hardwood or hardwood laminate. In preferred embodiments, the treads and risers are made of three layers—one layer of medium density fiberboard or plywood in the middle of two laminate layers. In addition, the outer surfaces of the treads and/or risers can feature other building materials such as tile or stonework. The finished treads and risers slide into place over the treads and risers that are part of the original stair box core. Because the treads and risers are beveled, sliding the treads and risers into place such that the back surface of the treads and the bottom surface of the risers tighten in place as they are pushed into place.
Hereinafter, the covers will be referred to generally by two different terms. “Safety cover” is the term that refers to the basic removable cover as they are typically used to both protect the stair box core and to aid the construction crew in seeing and identifying the individual steps as they use the stairs. The term “pre-finished cover” refers to the removable covers that feature some species of hardwood, laminate, or other decorative surface.
Another feature of this stair box system is a spacer board attached to the stringers. These spacer boards are attached to the outside surfaces of the stringers, i.e. the surfaces that are not engaged with the treads. This spacer board creates some separation between the stringers and the wall or other surface that is immediately adjacent to and flanks each of the stringers in a closed stair box system. Without the spacer in place, the dry wall or other wall building material, will need to be cut to conform to the shape of the individual stairs, i.e., multiple cuts will have to be made to fit the sheet rock around or over the individual treads and risers. In addition, the spacer boards can be used to join more than one stringer end to end, by attaching them to two stringers that are otherwise positioned end to end.
The inventor has adapted the above described system to a stair box with a single stringer, i.e., a stairway that is not flanked by walls immediately on one of its two sides. In these embodiments, the system works virtually identically to the system used for closed stairways; however, there is no need for the beveling of the treads and risers.
Referring now to the invention in more detail, in
In addition,
In practice, the stair box core 23 is assembled off-site and shipped to the construction site to be installed. While construction is underway, the inventor anticipates the construction crew will install safety covers 24 made of whatever material is both durable and cheap such as pressed wood or plywood. The safety covers 24 can consist of covers for the risers 13 and the treads 12, but the inventor's contemplated best mode only includes tread covers 17. In other words, the safety covers 24 can be thought of as a type of tread cover 17, usually featuring a nose 18. The safety covers 24 can be attached to the stair box core 23 with conventional fasteners such as screws, nails, nuts and bolts, adhesives, etc. with screws being the preferred means of attachment. Just as the treads 13 described above, the safety covers 24 are beveled or tapered such that the front surface of the cover is a little bit wider than the back surface of the safety cover. As a result, they are meant to be slid over the surface of the treads 12 that are part of the stair box core 23 and when they are slid in place, the safety cover 24 fits snugly in place as it is beveled or tapered to the same degree as the underlying tread 12 of the stair box core 23.
If desired, the safety covers 24 can feature noses 18 as described previously. With the safety covers 24, the noses 18 are preferably painted a bright color that does not match or blend into the wooden surface to ensure the construction crew can easily see the edge of each tread 12 as they are using the stairs while they are working. Later, when the rest of the construction is complete, the dry wall has been installed and painted and the other finish and trim work has been completed, the construction crew can detach and remove the safety covers 24 from the stair box core 23 and install pre-finished tread covers (not shown) which are essentially tread covers 17 that feature whatever desired building material on its outer surfaces the builder or homeowner requires whether it be a species of hardwood, tile, stone work or other decorative surface. The pre-finished covers are configured to slide into place over the treads of the stair box core 23 and separate pre-finished covers are configured to slide in place over the risers 13 of the stair box core 23. The pre-finished covers, like the underlying treads and risers 13 of the stair box system 10 are beveled or tapered to fit into place over the treads 12 and risers 13 of the stair box core 23.
This stair box system represents a significant departure from the prefabricated stair boxes that are already on the market. Specifically, all of the pieces and parts of this system can be cut using CNC machining thus reducing the amount of manual labor required to produce a prefabricated stair box. In addition, using CNC machining also helps to decrease the incidence of workplace injuries. It also allows for more efficient use of the building materials, generally lumber, as the process can be used to cut multiple components from a single sheet of lumber. For example, the strip of lumber that fits into the open faced channel formed by the hooks and notches on the risers and treads can be made from scrap lumber.
In addition, the system offers a number of obvious advantages over traditional prefabricated stair boxes. First, the treads and risers can be replaced without doing significant damage to the stair box and surrounding walls. Second, the stair box can be protected from weather and the elements while the building it is seated in is constructed. In addition, as mentioned above, the ability to change the surfaces of the treads and risers after the rest of the building has been constructed and the finish work has been completed decreases construction time and costs. Fourth, the spacer allows for the drywall or sheet rock or to be put in place to form the walls around the stair box more easily as the wall material need not be cut to fit over each individual stair.
Moreover, the system makes it easy to use a color coding system to identify the sizes of materials needed to replace the treads and risers when the owner desires to replace the flooring or other material covering the stairs. More specifically, one color is used to identify the width of the treads and risers, another color is used to identify the depth or run of each of the treads and a third color is used to identify the rise or height of each of the risers. As a result, the owner can pull up the carpet or detach a single tread, note the colors painted on a surface of the stair box and then order the appropriate materials to replace the treads and risers with a new pre-finished surface. Above and beyond any other feature, this system is highly and easily customizable.
Reference throughout the specification to features, advantages, or similar language does not imply that all of the features and advantages that may be realized with the present invention should be or are in any single embodiment of the invention. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, discussion of the features and advantages, and similar language, throughout the specification may, but do not necessarily, refer to the same embodiment.
Furthermore, the described features, advantages, and characteristics of the invention may be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize that the invention can be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the invention.
It is understood that the above described embodiments are only illustrative of the application of the principles of the present invention. The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiment, including the best mode, is to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, if any, in conjunction with the foregoing description.
While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the invention.
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20190032340 A1 | Jan 2019 | US |