BACKGROUND OF THE INVENTION
The invention relates to building construction and, in particular, to short span flat drywall ceiling construction.
PRIOR ART
A type of ceiling construction found in commercial buildings involves the use of horizontally spaced inverted metal tees suspended by wires from overlying structure. Sheets of drywall are fastened by screws to these metal tees and then are taped and otherwise finished. Building areas such as corridors, stairwells, landings, and small rooms found in apartments, condominiums, hotels, motels, dormitories, and the like are commonly finished with flat drywall ceilings. These building areas are typically relatively narrow and, therefore, involve a relatively short span from wall-to-wall. In many instances, the space or plenum above the ceiling, especially in corridors and hallways, is occupied by duct work, conduit, and mechanical equipment. The presence of this and like equipment frequently interferes with the installation of suspension wires. As a result, additional layout planning, tradesmen scheduling and, eventually, more labor, is incurred. Frequently, unforeseen physical interference problems add to the cost of construction.
SUMMARY OF THE INVENTION
The invention involves an improved tee construction that can advantageously be used for supporting flat drywall ceilings in extended “short span” applications. The disclosed tee construction is capable of supporting standard drywall sheets and satisfying applicable building codes while avoiding the need for suspension wires. The tees of the invention are sufficiently rigid to enable them to be supported exclusively at their ends on conventional wall angles. This rigidity avoids the labor of anchoring overhead suspension wires and the problems associated with interference with equipment in the space above the ceiling. The disclosed tees are commercially made with mostly existing technology, tooling, and material stock. Only a limited quantity of extra material is used in the manufacture of the disclosed tee forms of the invention.
More specifically, standard drywall tees are effectively rigidified by increasing their section modulus with a channel sized to closely fit with the standard reinforcing bulb provided at the top of the inverted standard drywall tee form. The resulting tee, in accordance with the invention, is familiar in form and size. The relatively low profile or height of the inventive tee affords full utilization of the space above the ceiling for free placement of utilities, duct work and like equipment without the need to leave clearance for suspension wires or to improvise and fabricate custom anchor points for the suspension wires. The freedom to use the full space of the plenum and not be hindered by suspension wires or supplemental brackets or supports is an important feature. This freedom is in addition to the basic cost savings obtained by eliminating the need for locating, installing, and tying off suspension wires.
The disclosed tee construction of the invention retains the benefit of a relatively light gauge tee body material and a single wall flange thereby affording easy and reliable penetration by self-drilling drywall screws.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an isometric schematic view of an extended short span flat drywall ceiling;
FIG. 2 is a fragmentary isometric view of the ends of the tees of the invention and their relation to a wall angle;
FIG. 3 is a diagrammatic illustration of the height-to-length ratio of the tee of the invention;
FIG. 4 is a fragmentary cross-sectional view of a first embodiment of the tee of the invention;
FIG. 5 is a fragmentary cross-sectional view of a second embodiment of the tee of the invention; and
FIG. 6 is a fragmentary cross-sectional view of a third embodiment of the tee of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 illustrates a corridor, hallway or other building area 10 characterized by a relatively short span ceiling structure 11 between opposing walls 12 and finished with a flat drywall surface. The term “flat” means that the drywall sheets are installed in a flat plane although their finished lower sides may be textured as is customary. Only a fragmentary area of the drywall 13 of the ceiling structure 11 is shown to reveal the arrangement of a plurality of tees 14 supporting the ceiling drywall.
The opposed walls 12 can be of any suitable construction. In reference to FIG. 2, the illustrated walls 12 are constructed of vertical sheet metal studs 16 on which are hung drywall sheets 17. It will be seen that the opposite wall assemblies formed by the studs 16 and drywall 17 serve as the vertical supports for the ceiling structure 11.
The ceiling structure 11 comprises a wall angle 18 on each of the opposed walls 12, support tees 14 extending between the wall angles, and drywall sheets 13 screwed to the lower sides of the tees. The wall angles 18 are conventional elements preferably formed from knurled or dimpled sheet metal strips and are nominally 1″ high by 1½″ wide or metric equivalents, and of, for example, a nominal gauge of 0.020 inch thickness. The wall angles 18, typically, are secured to the walls 12 with self-drilling drywall screws 21 driven through the drywall sheets 17 into the studs 16.
FIG. 4 illustrates a first embodiment of a tee 26 in cross-section. The tee has a main body 27 roll-formed of a single strip of sheet metal. The strip is, for example, relatively light gauge stock being about 0.018″ galvanized (G40) hot-dipped steel (HDG). The form of the tee main body 27 is conventional. At the lower side, the tee main body 27 includes a single layer horizontal flange 28 comprising oppositely extending parts 29. Distal edges of the flange parts 29 have hems 31 folded over their upper sides. Adjacent and parallel to their distal edges, the flange parts 29 have small grooves 32 that serve to restrain screws from “skating” laterally off of the lower face of the flange 28 when being screwed into the flange. Additionally, the lower face of the flange 28 can be knurled, as is known, to stabilize a screw tip and further prevent it from skating across this lower flange face. At their proximal edges, the flange parts 29 merge integrally with respective layers 33 of a double layer or double wall vertical web 34. The web layers 33 are fixed together by a suitable fastening process such as the stitching technique shown in U.S. Pat. No. 6,047,511, clinching as shown in U.S. Pat. No. 6,041,564, or by welding, adhesives, or other known expedient. The web layers 33, at their upper edge, merge integrally with a hollow reinforcing bulb 36. More specifically, the web layers 33 join lower sides 37 of the bulb 36. In the illustrated example, the lower sides 37 of the bulb 36 are nearly horizontal, being nominally about 5 degrees off true horizontal. The bulb 36 is generally rectangular in cross-sectional shape. By way of example, the flange 28 from edge-to-edge can extend nominally 1½″ and the height of the tee main body 27 from the bottom face of the flange 28 to the top face of the bulb can be nominally 1⅝″, or metric equivalents.
A roll-formed sheet steel inverted channel 41 is closely fitted and assembled in the interior of the bulb 36. The material of the channel 41 can be slightly heavier in gauge than the tee main body 27. For example, the stock forming the channel 41 can be a nominal minimum of 0.024″ thick. Ideally, a bight 42 of the channel 41 abuts the upper wall of the bulb 36. The channel 41 ordinarily will run from end-to-end of the tee main body 27. The channel 41 can be locked in the illustrated position by appropriately punching or piercing the sidewalls, designated 43 of the bulb 36 at spaced locations along the length of the main tee body 27.
FIG. 3 diagrammatically illustrates the relative geometry of the tee 26 formed by the main body 27 and the channel insert 41. The height “H” of the tee main body 27 is nominally 1⅝″ and the length of the tee 26 will be between about 7′ and about 8½′ to about 9′, for example. It has been projected that a length greater than a dimension between about 9′ to about 9½′ would require an amount of additional channel stock which would make the disclosed tee construction uneconomical. The tee 26 ordinarily obtains its vertical support solely at its ends from reaction forces developed by the wall angles 18. That is, the tees 26 are sufficiently rigid to be devoid of any vertical support along the entire span between the wall angles 18. This capability eliminates the labor and materials attendant with hanging suspension wires from overhead structures and leaves the full space above the tees 26 available for building equipment. In FIG. 3, the length L denotes the length of the tees.
FIG. 4 shows the relationship of a sheet 13 of drywall and a typical tee. By way of example, the drywall sheet 13 is illustrated as ⅝″ thick; where appropriate ½″ thick drywall can be similarly used. As is customary, a plurality of self-drilling drywall screws 21 secure the drywall sheet 13 to the bottom of the tee flange 28. The single wall light gauge character of the tee main body 27 is of great advantage over heavier gauges or double-layer flanges because it is relatively easy to pierce this stock with a common, commodity quality self-drilling drywall screw.
FIG. 5 illustrates a second embodiment of a tee 46 in cross-section. A tee main body can be identical to the tee main body 27 disclosed in connection with FIGS. 1-4. In the tee 46 of FIG. 5, an inverted channel 48 is fitted, cap-like, over the reinforcing bulb 36. Channel 48 is preferably roll-formed from a strip of sheet steel of a gauge somewhat heavier than the gauge of the main tee body 27. The channel gauge can be nominally a minimum of 0.024″, for example. The channel 48 includes a pair of sides 49 proportioned to closely abut the sides of the hollow reinforcing bulb 36 and to extend vertically over a major portion of the vertical height of the bulb. The channel 48 is rigidly fixed in place on the main body by appropriate staking, piercing, riveting, welding, or the like. The length of the channel 48 need not extend the full length of the main tee body 27 and can, for example, be half or more in length as the length of the tee main body and be centered lengthwise over the tee main body.
FIG. 6 illustrates yet another embodiment of an extended short span tee 51. The tee 51 utilizes the tee main body 27, referenced in connection with FIGS. 1-5, and a unique inverted ribbed channel 52. The channel 52, like the earlier described channels 41, 48 is, ideally, a one-piece or integral roll-formed sheet steel strip preferably of a nominal gauge heavier than that of the tee main body 27 such that it has a nominal minimal thickness of 0.024″, for example. The channel has vertical depending legs 53, horizontal webs 54 and an upstanding double wall central flange or rib 56. Preferably, the height of the rib above the bulb 36 is at least one-half the height of the sidewalls 43 of the bulb. The webs 54 bridge the distance between the legs 53 and the rib 56. The channel 52 is shaped to cause the legs 53 to abut the sides of the bulb 36. The legs 53 cover a substantial portion of the height of the bulb sides. The channel 52, like the channel 41 of FIG. 5, need not extend along the full length of the tee main body 27 and can be about half as long as the tee main body and be centered on its length. The channel 52 is fixed in position in the same manner as described in connection with the channel 41 of FIG. 5. The rib or flange 56 adds significantly to the rigidity of the tee 51 in a vertical plane.
While the invention has been shown and described with respect to particular embodiments thereof, this is for the purpose of illustration rather than limitation, and other variations and modifications of the specific embodiments herein shown and described will be apparent to those skilled in the art all within the intended spirit and scope of the invention. Accordingly, the patent is not to be limited in scope and effect to the specific embodiments herein shown and described nor in any other way that is inconsistent with the extent to which the progress in the art has been advanced by the invention.
Patent Application
20100257807
