Abstract:
A seismic wall molding for suspended ceiling systems that, although sufficiently wide across its horizontal ceiling supporting leg, is visually unobtrusive by virtue of a stepped, shadow style configuration. The stepped horizontal leg configuration allows the wall molding to resist buckling or bending deformation in the horizontal leg when a vertical leg of the molding is tightly secured against a non-flat wall surface. Factory ends on the wall molding are at parallel 45 degree planes to facilitate making inside and outside corners at the job site. A factory supplied template simplifies corner construction. A splice piece fits tightly on the upper sides of the horizontal legs at a straight-line joint between abutting lengths of the wall molding to maintain these elements in alignment.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to suspended ceiling structures and, in particular, to improvements in perimeter trim for suspended ceiling systems. 
     PRIOR ART 
     Suspended ceiling systems of the type comprising a rectangular grid and lay-in tiles ordinarily use wall mounted trim or molding, most commonly in the general form of an angle, to support ends of the grid elements and edges of the tiles. Seismic building standards have evolved that specify that a wall angle or perimeter trim have a relatively wide horizontal leg. This requirement is to ensure that when seismic activity causes the suspended parts of a ceiling to shift horizontally relative to the walls that the elements supported by the wall molding do not slip off the wall molding. With regular perimeter trim of limited width, there is a risk that the ceiling components can slip off the horizontal leg of the trim or molding. 
     Wide horizontal flanges or legs on a wall molding present problems for the architect and the installer. A wide plain face on the visible horizontal leg is often undesirable for aesthetic reasons including the fact that the trim looks out of proportion to the grid elements of the ceiling. Another sometimes very troublesome problem encountered with wide face trim is distortion of the horizontal leg out of its design plane. This distortion occurs when the vertical leg is secured against a wall that in local areas is not flat. When the vertical leg is drawn tight against a non-flat wall area, particularly where the wall is locally concave, the horizontal leg distorts from its free state. Drywall seams and misaligned or bowed studs and/or improperly set fasteners, all of which in practice may be unavoidable, are typical causes of irregular non-flat wall surfaces. The resulting distortion in the wall molding can be severe enough to render the installation unacceptable if not somehow corrected. 
     Adding to the difficulties faced by an installer of a suspended ceiling are the problems of creating a gap free and aligned joint between adjacent lengths of wall molding. These problems are particularly acute where the visible face of the horizontal leg is stepped such as found in a so-called shadow-type wall molding. 
     SUMMARY OF THE INVENTION 
     The invention provides a perimeter trim or wall molding construction suitable for service in areas where seismic building standards are applicable. The invention solves the problems associated with wide faced horizontal support legs needed to comply with seismic building standards. The perimeter trim of the invention has its horizontal relatively broad supporting leg formed in stepped sections. The relatively broad leg, thus, not only forms shadow lines giving it a less massive appearance, but is also reinforced against the tendency to buckle out of its free state plane. 
     The stepped configuration of the horizontal leg preferably includes a vertical stiffening portion adjacent the free edge of the leg. This location allows this stiffening portion to provide a proportionately high degree of rigidity and resistance to buckling or other deflection at the free edge where such deflection is typically greatest and most conspicuous. 
     In accordance with an aspect of the invention, individual pieces or lengths of the wall molding can be factory end cut at a 45 degree angle to facilitate field installation of both inside and outside corners. The factory ends are parallel to one another so that, as disclosed, one or the other end of a piece can be used to form an inside or outside corner, respectively. A factory-provided template enables the installer to quickly hand cut an end of a length of the wall molding to fit the appropriate factory mitered end to form the desired inside or outside corner. A splice can be furnished to assure that at straight end-to-end joints, the visible wide legs are in alignment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a fragmentary plan view of a wall molding constructed in accordance with the invention; 
         FIG. 1A  is a fragmentary elevational view of the wall molding of  FIG. 1 ; 
         FIG. 2  is a cross-sectional view of the wall molding of  FIG. 1  taken at the plane indicated at the lines  2 - 2  in  FIG. 1 ; 
         FIG. 3  is a fragmentary plan view of an inside corner of two pieces of the wall molding; 
         FIG. 4  is a fragmentary plan view of an outside corner of two pieces of the wall molding; 
         FIG. 5  is a plan view of a template for cutting the wall molding for inside and outside corners; 
         FIG. 6  is a perspective view of the template of  FIG. 5 ; 
         FIG. 7  is a fragmentary plan view of two lengths of the wall molding arranged in a straight line joint and maintained in alignment with a splice; 
         FIG. 7A  is a view similar to  FIG. 7  showing the splice used in a straight butt joint; 
         FIG. 8  is a cross-sectional view of the joint of  FIG. 7  taken in the plane indicated by the lines  8 - 8  in  FIG. 7 ; 
         FIG. 9  is a fragmentary cross-sectional view in a vertical plane of a suspended ceiling system employing the wall molding of the invention; 
         FIG. 10  is a view similar to  FIG. 1  showing a modified form of the wall molding having blunted ends; 
         FIG. 11  is a fragmentary plan view similar to  FIG. 3 , showing an inside corner of two pieces of the wall molding of  FIG. 10 ; and 
         FIG. 12  is a fragmentary plan view similar to  FIG. 4 , showing an outside corner of two pieces of the wall molding of  FIG. 10 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings and, in particular,  FIGS. 1 and 2 , a length or piece of perimeter trim is illustrated at  10 . The trim  10 , also referred to as wall molding, is preferably made by roll-forming a strip of sheet metal stock into the cross-section illustrated in  FIG. 2 . Typically, the sheet stock is steel with a thickness of, for example, about 0.021″ to about 0.024″. Ordinarily, each length or piece  10  of wall molding is 10 feet or 12 feet long (i.e. the length of either longitudinal edge). 
     With reference to  FIG. 2 , the wall molding includes a generally flat vertical leg or flange  11  and a generally horizontal leg  12 . The legs  11 ,  12  are integrally joined at a 90 degree corner  13 . When the term “horizontal” is used to describe the leg  12 , it is used in the general sense to cover parts or elements that extend or exist horizontally away from the wall or corner  13  and are active in supplying directly or indirectly vertical support of the ceiling grid and tiles of a suspended ceiling system. The horizontal leg  12 , which in use, as will be discussed, supports adjacent suspended ceiling structure, has two generally horizontal sections  16 ,  17  and a generally vertical stiffening web  18  extending between and integral with the sections  16 ,  17 . The illustrated sections  16 ,  17  are unequal in width, but not limited to that, the section  16  adjacent the corner  13  being about ¾″ wide and the section distal from the corner being about 1¼″ wide. The proportionate width of the sections  16 ,  17  can be varied as desired, but their combined width should be at least about 2″ to satisfy seismic code requirements. 
     A hem  21  is formed on an upper edge  22  of the vertical leg  11  distal from the corner  13  by folding the sheet material back on itself to reinforce this edge. The hem  21  is sufficiently folded so that an actual edge  23  of the sheet stock contacts the vertical leg  11  at a line below the upper edge  22 . 
     Adjacent a free edge  24  of the horizontal leg section  17 , the horizontal leg  12  includes a vertical stiffening flange or element  26 . The stiffening flange  26  is integrally joined to the leg section  17  at a 90 degree corner  27  and has a hem  28  at its upper edge  29 . The sheet material of the hem  28  is folded back so that its actual edge  31  contacts the stiffening flange  26  at a line below the stiffening flange edge  29 . The free edge  29  of the stiffening flange  26  is preferably at least at the elevation of an upper face  32  of the horizontal leg section  16  proximal to the corner  13 . The various parts of the wall molding  10  described with reference to  FIG. 2  extend longitudinally for the length of the wall molding. 
     The wall molding or perimeter trim  10 , in a conventional manner, is secured to a wall  37  with suitable fasteners  36 , such as screws, nails or staples at the desired plane of the ceiling. As shown in  FIG. 9 , the vertical leg  11  is held tightly against the wall  37  by fasteners  36  driven into a structural wall member  38  such as a metal or wood stud, or a monolithic wall. 
     When conventional wall moldings with wide seismic rated horizontal legs are installed on non-flat walls, these legs are prone to severely distort out of their free state shape particularly when the geometry of the wall is locally concave. The disclosed wall molding or trim piece  10  has demonstrated a high level of resistance to this kind of distortion. One factor contributing to this desirable characteristic is the vertical flange or rib  26  that stabilizes the outer or distal horizontal leg or face section  17 . Preferably, as mentioned, the flange  26  stands at least as tall as the difference in elevation between the horizontal leg sections  16 ,  17 . In one arrangement, the vertical leg  11  has a height measured from the plane of a lower face  41  of the proximal horizontal leg section  16  to the upper edge  22  of ⅞″ or 1″ while the height of the vertical flange  26  is about 9/32″ (nominally 0.274″) where the difference in elevation between the horizontal leg sections  16 ,  17  is nominally ¼″ and the material thickness is between about 0.021″ to 0.024″. Stated in other words, the height of the vertical flange  26  is preferably more than ¼ of the height of the vertical leg  11  and can be less than ⅓ of the height of the vertical leg when the vertical leg is ⅞″ tall. 
     For appearance, it is important that the free edge of the distal section  17  of the horizontal leg at the corner  27  remains as flat or straight as possible in the lengthwise direction. Flatness at this location by avoiding any buckling or bending distortion from the free state flat condition of the wall molding  10  is important because this is the area of the molding that is most conspicuous when distortion occurs. While the exact phenomena is not known, it is believed that the superior resistance to buckling or other distortion at the free edge  24  of the horizontal leg section  17  is attributable to two stages of vertical stiffening elements, namely, the vertical web  18  and the vertical flange  26 . Propagation of strain into the outer or distal horizontal leg section  17  is reduced by the existence of the web  18  which serves to resist vertical buckling in the horizontal leg and which, in a bellows-like effect, reduces the transmission of horizontal strain imposed on the molding  10 , when its vertical leg  11  is drawn against a non-flat wall area, between the horizontal leg section  16  adjacent the vertical leg  11  and the distal horizontal leg section  17 . 
     The illustrated cross-sectional form of the wall molding  10  is beneficial for additional reasons with the vertical flange  26  extending substantially at least as high as an upper face  42  of the inner or proximal horizontal leg section  16 , tees  46  and ceiling tiles  47  of a suspended ceiling system  48  ( FIG. 9 ) can rest on the vertical flange  26  and be free to slide over this upper face during seismic activity. The spacing of the vertical web  18  from the vertical leg  11  is nominally about ¾″ so that it can be used by an installer as a gauge to measure the required clearance as required by the applicable seismic building code. Where tees  46  are anchored to the wall molding  10 , the tees extend over the proximal section  16 . Pop rivets or screws through the section  16  and ends of the tees  46  are advantageously somewhat hidden from view by the vertically recessed character of this section. Similarly, the distal section  17 , by virtue of being lower than the section  16  and the corner  13  serves somewhat to conceal gaps between the molding  10  and wall  37 . 
       FIGS. 7 and 8  illustrate a manner by which the ends of two abutting pieces of wall molding  10  are maintained in alignment at the horizontal legs  12 . A specially formed separate splice  51  is provided to bridge the joint, designated by the numeral  52 , and constrain the horizontal sections  12  to a common plane. The illustrated splice  51  is a sheet metal stamping of generally rectangular form. One of the long edges of the splice  51  has a relatively short vertical flange  53  while the opposite long edge is serrated to form a series of teeth  54 . The splice  51  is slightly bent at a line  56  through a small angle so that a portion  57  carrying the teeth  54  is in a plane obtuse to the plane of the remaining portion  58 . The splice  51  is proportioned so that the flange  53  fits vertically tightly under the edge  31  of the hem  28 . When the splice flange  53  is against the wall molding flange  26 , the splice  51  is proportioned so that the teeth  54  fit tightly and grip an opposing face of the vertical web  18 . In use, the splice  51  is positioned as indicated in  FIG. 7  so that it bridges the actual joint  52  between the abutting pieces of wall molding  10 . The flange  53  is positioned under the hem edges  31  and splice teeth  54  are pressed downwardly until the teeth firmly grip the web faces. The bend  56  allows the splice  51  to resiliently deform by increasing the bend angle so as to account for dimensional variations in the individual wall molding pieces and/or the splice and to allow the splice to be retained in place with a spring-like action. The splice  51 , when it is in place, as described, because the flange  53  is straight and tight fitting, forces the free edges of the abutting wall molding pieces  10  into mutual alignment.  FIG. 7A  illustrates the use of the splice  51  at a butt joint between two lengths of wall molding  10  that are abutted at their ends  66 ,  67  which lie in planes transverse to their longitudinal directions. 
     As indicated in  FIG. 1 , for example, the wall molding  10  can be factory produced with angled ends  59 ,  60 . More specifically, the horizontal legs  12  can be formed with ends  59 ,  60  that are cut diagonally to the longitudinal direction of the molding  10 , most commonly, at a nominal 45 degree angle with the ends parallel to one another so as to give the horizontal leg  12  in plan view a rhomboid shape. This style of factory end facilitates field construction of inside and outside miter joints. One end  59  of the molding  10  is suitable for use at inside corners, while the opposite end  60  is suitable for outside corners.  FIG. 3  illustrates an inside corner in plan view. A mating piece of wall molding  10  is specially field cut at its end preferably by using a template  61 . The template  61 , which in the disclosed embodiment is double ended, can be supplied by the factory for use by the installer. The template  61  with the proper end orientation, is saddled over the wall molding piece to be cut, lines are scribed according to the edges of template end  62 , and the piece is cut on the scribed lines, typically with aviation cutters or tin snips. The resulting geometry of the end cut on the mating piece  10  enables it to overlie portions of the factory edge  59  and rest on upper surfaces of the horizontal sections  16 ,  17  of the horizontal leg  12  at the factory edge. The result is a faux miter joint where the factory edge  59  is essentially the only edge that is visible from below the ceiling. 
       FIG. 4  illustrates the construction of an outside joint in essentially the same manner as that described for the inside joint of  FIG. 3 . The opposite end, designated  63 , of the template  61 , is used to fashion the end of the mating piece  10  so it overlies the factory cut edge  60 . The faux miter joints shown in  FIGS. 3 and 4  produced in the manner described are of high quality since, for the most part, the only visible sight lines at the joint are the factory cut edges  59 ,  60  and these factory sight lines are unaffected by slight angular, longitudinal or lateral misalignments between the joined pieces. 
       FIGS. 10-12  illustrate a modified form of the wall molding  110  in which the ends are blunted. The same numerals are used to designate the same parts of the molding  110  as described in connection with the molding  10 . As shown in  FIGS. 10-12 , tips  71 ,  72 ,  73  and  74 , i.e. primarily the vertical leg  11  and the vertical stiffening flange  26  are cut at right angles to the longitudinal direction of the wall molding  110 . Factory miter edges  159  and  160  are at a nominal 45 degrees to the longitudinal direction of the wall molding. This angle can vary up to about 48 degrees, measured from a plane perpendicular to the longitudinal direction of the molding, to improve the fit and appearance of the faux miter joint. A modified template, corresponding to the template  61 , can be provided to accommodate these changes. 
     It should be evident that this disclosure is by way of example and that various changes may be made by adding, modifying or eliminating details without departing from the fair scope of the teaching contained in this disclosure. The invention is therefore not limited to particular details of this disclosure except to the extent that the following claims are necessarily so limited.