Static structures (e.g. – buildings) – Openwork; e.g. – truss – trellis – grille – screen – frame – or... – Three-dimensional space-defining
Reexamination Certificate
1998-11-25
2001-10-16
Chilcot, Richard (Department: 3635)
Static structures (e.g., buildings)
Openwork; e.g., truss, trellis, grille, screen, frame, or...
Three-dimensional space-defining
C052S262000, C052S655100, C052S702000, C052S656900
Reexamination Certificate
active
06301854
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
FEDERALLY SPONSORED RESEARCH
Not applicable.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The subject invention relates to building components and, more particularly, to floor joists and floor systems fabricated from metal.
2. Description of the Invention Background
Traditionally, the material of choice for new residential and commercial building framing construction has been wood. However, over the years, the rising costs of lumber and labor required to install wood framing components have placed the dream of owning a newly constructed home out of the economic reach of many families. Likewise such increasing costs have contributed to the slowing of the development and advancement of urban renewal plans in many cities. Other problems such as the susceptibility to fire and insect damage, rotting, etc. are commonly associated with wood building products. Additional problems specifically associated with wooden floor joists include cost, availability and quality. These problems are particularly acute with respect to larger joists which must be harvested from large old growth forests which are becoming depleted.
In recent years, in an effort to address such problems, various alternative building materials and construction methods have been developed. For example, a variety of metal stud and frame arrangements have been developed for use in residential and/or commercial structures. U.S. Pat. No. 3,845,601 to Kostecky discloses such a metal wall framing system. While such system purports to reduce assembly costs and the need for welding or separate fasteners, several different parts are, nonetheless, required to complete the wall frame system which can be time consuming and expensive to inventory and assemble. Such components must also be manufactured to relatively close tolerances to ensure that they will fit together properly thereby leading to increased manufacturing costs. Other metal stud systems for fabricating walls are disclosed in U.S. Pat. No. 3,908,328 to Nelsson, U.S. Pat. No. 4,078,347 to Eastman et al., U.S. Pat. No. 4,918,899 to Karytinos, U.S. Pat. No. 5,394,665 to Johnson, and U.S. Pat. No. 5,412,919 to Pellock et al. Such patents are particularly directed to wall system constructions and do not address various problems commonly encountered when installing floor and/or ceiling joists and support structures therefor within a building.
Conventional floor construction methods typically comprise installing “header” members on the top of support walls that may be fabricated from, for example, concrete blocks, wood or metal studs. The header members typically comprise wood beams that are supported on edge on the wall. Other wood beam members, commonly referred to as joists, are used to span from wall to wall between the headers and are usually connected to the headers by nails. The joists are typically arranged parallel to each other with 8″, 16″ or 24″ between their respective centers, depending upon the load characteristics that the floor must accommodate. A sheathing material such as plywood is then nailed to the upper edges of the joists to form the floor surface. To prevent the joists from inadvertently twisting or moving laterally, small pieces of wood, known as blocking pieces, are commonly nailed between adjacent joists to form, in many instances, X-shaped braces between the joists. Insulation is sometimes installed between the joists and sheathing, drywall, plasterboard, etc. is then applied to the bottom of the joists to form a ceiling for the space located under the floor joist system.
While these materials and floor construction arrangements have been used for many years in residential and commercial construction applications, they have many shortcomings that can contribute to added labor and material costs. For example, when connecting the joists to their respective headers, the carpenter must first measure and mark the headers to establish the desired joist spacing. This additional step increases the amount of construction time required to install the floor system and, thus, results in increased construction costs. After the headers are installed, the joists must be properly nailed to the headers. If the carpenter has access to the opposite side of the header from which the joist is to be installed, the nails are hammered through the header into the end of the respective joist. If, however, the carpenter cannot access the opposite side of the header, nails must be inserted at an angle (commonly referred to as “toenailing”) through the joist and into the header. Care must be taken to avoid inadvertently splitting the joist and to ensure that the nails extend through the joist and into the header a sufficient distance. Such attachment process can be time consuming and may require the use of skilled labor which can also lead to increase construction costs. If toenailing is not structurally acceptable, another piece, called a joist hanger must be added which also increases labor and material costs.
It is also often desirable to install ductwork, piping, electrical wires, etc. within the floor joist system so that they do not occupy living space and are concealed by the ceiling material that is attached to the bottom of the joists. To accommodate those elements that must span multiple joists, passageways and/or holes must be provided through the joists. The number, size, and location of such passageways/holes must be carefully considered to avoid compromising the structural integrity of the joists. Furthermore, the blocking members may have to be moved or eliminated in certain instances to permit the ductwork and/piping to pass between the joists. In addition, cutting such passageways/holes into the joists at the construction site is time consuming and leads to increased labor costs. Another shortcoming associated with such floor joist systems is the difficulty of installing insulation between the joists due to the blocking members.
As noted above, there are many shortcomings associated with the use of wood floor joists and headers. In an effort to address some of the above-noted disadvantages, metal beams have been developed. For example, U.S. Pat. No. 4,793,113 to Bodnar discloses a metal stud for use in a wall. U.S. Pat. No. 4,866,899 to Houser discloses a metal stud that is used to support wallboard panels for forming a fire-rated wall and is not well-suited for supporting structural loads. U.S. Pat. No. 5,527,625 to Bodnar discloses a roll formed metal member with reinforcement indentations which purport to provide thermal advantages. The studs and metal members disclosed in those patents, however, fail to address many of the above-noted shortcomings and can be time consuming to install. Furthermore, many of the metal beams, studs, etc. disclosed in the above-mentioned patents typically must be cut in the field using hand tools. Such cuts often result in sharp, ragged edges which can lead to premature failure of the component when it is placed under a load.
In an apparent effort to better facilitate installation of various beams, U.S. Pat. No. 3,688,828 to Nicholas et al. discloses the use of L-shaped brackets to facilitate attachment of eaves boards and rafters to a C-shaped channel. While such arrangement may reduce assembly costs at the construction site, such brackets must be welded or separately affixed to the C-shaped channel which is time consuming and leads to increased manufacturing and fabrication costs. Furthermore, significant skill is typically required to properly layout and align the brakets.
Currently, metal floor joist material is generally cost-competitive with wood material. However, the nuances of assembling existing metal joists generally make them non-competitive when compared with wood joist arrangements.
Thus, there is a need for a floor joist that is relatively inexpensive to manufacture and install.
There is a further need for a floor joist that can permit the passage of ductwork, piping, electrical wires, etc. therethrough without compromising the st
Daudet Larry Randall
Ponko Edmund L.
Ralph Gregory S.
Chilcot Richard
Dietrich Industries, Inc.
Kirkpatrick & Lockhart LLP
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