Patent Publication Number: US-2007113511-A1

Title: Truss and purlin support apparatus and a method of making and using same with building supports and floor and roof sheathing

Description:
FIELD OF THE INVENTION  
      The present invention relates to the field of floor and roof support apparatus and, more particularly, to a truss and purlin support apparatus and a method of making and using same with building supports and floor and roof sheathing.  
     BACKGROUND OF THE INVENTION  
      In the construction industry for buildings, including residential, commercial and institutional and high rise, there is a continuing need to achieve higher economic efficiencies in cost of materials, of fabrication, and of installation labor for floor and roof systems, as well as to achieve improved floor and roof structural efficiency. Though still largely undeveloped, the construction industry may be beginning to consider the use of light gauge steel (hereinafter, alternately referred to as “LGS” and/or “light weight steel”) constructions in this regard.  
      In the prior art, conventional floor constructions in LGS may heretofore have used “C”-channel floor joists  30 , such as those assembled as illustrated in  FIG. 1 . Such prior art LGS floor systems may have included the use of such “C”-channel floor joists  30 , in a back-to-back orientation, in typical depths of 8″, 10″, 12″, and 14″, and in typical gauges ranging between 18 gauge and 14 gauge. As illustrated in  FIG. 1 , such prior art floor joists  30 , in the aforesaid back-to-back orientation, may heretofore have been supported on external foundation walls  22  and on center load bearing walls  24 . Such prior art installations may often have also required the use of rim joists  34  and “X”-bracings  36 , throughout, to provide a requisite level of stability for the floor, and/or to reduce the likelihood that the prior art joists  30  might fall over under load conditions (not shown). It would be desirable to provide a floor system that does not required the use of such rim joists  34 . In addition, prior art stiffening members  32  may heretofore have been required to reduce the likelihood of web crippling which may arise under concentrated loads (e.g., from wall studs in situations where multiple stories are present). Such prior art floor systems, especially insofar as they may have been constructed of LGS, may have been very time-consuming to construct and cumbersome to install, and often may have been quite costly in terms of material costs.  
      In addition, prior art systems that included “C”-channel joists  30  have been subject to the significant problem of providing the requisite level of stability for the “C”-channel joists  30  in their upright position (as shown in  FIGS. 1 and 2 ). The aforementioned problem may heretofore have been especially acute in situations where the “C”-channel joists  30  may have spanned over three walls (i.e., where the floor system is supported by two exterior foundation walls  22  and by a third center load-bearing wall  24  substantially at the mid-point of the floor). Although the prior art rim joists  34  may have provided some measure of increased stability at the extremities, the “C”-channel joists  30  may not have been sufficiently stable at the at center load bearing wall  24 . As well, certain minimum bearing requirements for floor joists resting on supporting structures, in this case the load bearing wall  24 , may have necessitated the overlap of the prior art “C”-channel joists  30  in the manner best seen in  FIG. 2 . That is, it may heretofore have been necessary, as shown in  FIG. 2 , to overlap adjacent ones of the “C”-channel joists  30  on top of the supporting structure. The aforementioned problems of collapsing and/or over-turning under concentrated loads is one which may have been inherent in such prior art arrangements. As such, in the prior art, it may have been necessary to install expensive “X”-bracing  36  within such prior art floor systems, which (apart from the significant added expense) may heretofore have been particularly difficult to accomplish for LGS constructions.  
      Use of prior art floor systems may also have presented additional headaches insofar as an “offset seam” may have been present (as indicated generally by arrows “Z” in  FIG. 2 ). Floor sheathing that might heretofore have been placed on top of the offset prior art “C”-channel joists  30  often may not have been properly and/or readily aligned therewith. In the result, considerable adjustments may have been necessitated during installation of sheathing over such prior art floor systems and may not have lended itself to a clean construction detail.  
      The aforementioned problem with prior art floor systems may have been somewhat more pronounced in low rise hotel constructions where a multitude of units, separated merely by center load bearing walls  24 , may be present adjacent to one another. In such situations, and/or if several floors are constructed on top of each other, prior art “C”-channel joists  30  may have become particularly unstable. Extreme care and “X”-bracing  36  may heretofore have been required to achieve a requisite level of stability, especially when under an applied load of several building stories. Moreover, such uses of prior art systems may not have afforded and/or guaranteed the desired level of sound stability, especially when under an applied load of several building stories.  
      It is thus an object of this invention to obviate or mitigate at least one of the above mentioned disadvantages of the prior art.  
     SUMMARY OF THE INVENTION  
      In accordance with the present invention, there is disclosed a truss and purlin support apparatus for use with building support members and a substantially planar substrate sheathing member. The apparatus includes a plurality of Pratt-style elongate truss members and a plurality of purlin members. Each of the truss members has at least two support portions longitudinally spaced from one another. The support portions are adapted to operatively engage and transfer loads to the building support members. Each of the truss members includes an elongate top chord, an elongate bottom chord, and a plurality of web members securely extending between the top chord and the bottom chord. Each of the purlin members extends in a substantially transverse direction relative to the elongate truss members. Each of the purlin members has an underside portion that is shaped to define a plurality of notched portions. The notched portions are spaced from one another in the transverse direction along the underside portion. Each of the notched portions is saddled over a respective top chord of the truss members, so as to restrict sliding movement of the purlin members in the transverse direction. The purlin members operatively support the substrate sheathing member thereon. The top chord, the bottom chord, the web members, and the purlin members are constructed from roll-formed light gauge steel material.  
      According to an aspect of one preferred embodiment of the invention, each of the truss members may preferably, but need not necessarily, have a center of gravity that is operatively located below the support portions.  
      According to an aspect of one preferred embodiment of the invention, neighboring ones of the truss members may preferably, but need not necessarily, be spaced by a truss on-center distance in the substantially transverse direction that is selected from the group consisting of about 36 inches and about 48 inches.  
      According to an aspect of one preferred embodiment of the invention, neighboring ones of the purlin members may preferably, but need not necessarily, be spaced by a purlin on-center distance in a substantially longitudinal direction that is selected from the group consisting of about 16 inches and about 24 inches.  
      According to an aspect of one preferred embodiment of the invention, each top chord and each bottom chord may preferably, but need not necessarily, be shaped, in profile, so as to define a substantially “U”-shaped chord portion and two substantially “L”-shaped chord portions. The “U”-shaped chord portion may preferably, but need not necessarily, include two substantially planar chord side portions extending substantially at right angles from opposing ends of a substantially planar central chord base portion. The chord side portions may preferably, but need not necessarily, define a web-receiving aperture therebetween. Each of the “L”-shaped chord portions may preferably, but need not necessarily, include a substantially planar first chord segment and a substantially planar second chord segment. The first chord segment may preferably, but need not necessarily, extend in a substantially outward direction and substantially at right angles from a respective one of the chord side portions. The second chord segment may preferably, but need not necessarily, extend substantially at right angles from the first chord segment. In each of the truss members, the web-receiving aperture of the bottom chord may preferably, but need not necessarily, face in a substantially upward direction and the web-receiving aperture of the top chord may preferably, but need not necessarily, face in a substantially downward direction. Each of the web members may preferably, but need not necessarily, extend into each web-receiving aperture, and securely engage each “U”-shaped chord portion, of the top chord and of the bottom chord.  
      According to an aspect of one preferred embodiment of the invention, one or more of the central chord base portion and the chord side portions of each top chord and each bottom chord may preferably, but need not necessarily, be shaped so as to define a stiffening projection substantially along a longitudinal extent thereof, whereby each top chord and each bottom chord may preferably, but need not necessarily, be provided with structural rigidity.  
      According to an aspect of one preferred embodiment of the invention, in each top chord and in each bottom chord, the chord side portions may preferably, but need not necessarily, be shaped so as to define a plurality of longitudinally spaced locator apertures therein. Each of the web members may preferably, but need not necessarily, be provided with end portions that are each shaped to define a locator aperture mating portion. Each of the web members may preferably, but need not necessarily, be located within each web-receiving aperture, and securely engage each “U”-shaped chord portion, of the top chord and of the bottom chord. Each locator aperture mating portion may preferably, but need not necessarily, be substantially securely aligned with one of the locator apertures.  
      According to an aspect of one preferred embodiment of the invention, each of the truss members may preferably, but need not necessarily, additionally include two support stiffening members, each preferably, but not necessarily, securely engaging the top chord substantially adjacent to a respective one of the support portions. Each of the support stiffening members may preferably, but need not necessarily, be positioned within the web-receiving aperture of the top chord. The support stiffening members may preferably, but need not necessarily, substantially maintain local structural integrity of the support portions preferably, but not necessarily, whilst the support portions operatively transfer the loads to the building support members.  
      According to an aspect of one preferred embodiment of the invention, each of the support stiffening members may preferably, but need not necessarily, be shaped, in profile, so as to define a substantially “C”-shaped support stiffening portion. The “C”-shaped support stiffening portion may preferably, but need not necessarily, include two substantially planar support side portions extending substantially at right angles from opposing ends of a substantially planar central support base portion. The central support base portion may preferably, but need not necessarily, be positioned substantially vertically within the web-receiving aperture of the top chord.  
      According to an aspect of one preferred embodiment of the invention, each of the purlin members may preferably, but need not necessarily, be shaped so as to define, remotely of the notched portions, a substantially “C”-shaped purlin profile that faces in the substantially downward direction.  
      According to an aspect of one preferred embodiment of the invention, the “C”-shaped purlin profile may preferably, but need not necessarily, be defined by a substantially planar central purlin base portion and two substantially “L”-shaped purlin portions. Each of the “L”-shaped purlin portions may preferably, but need not necessarily, include a substantially planar first purlin segment and a substantially planar second purlin segment. The first purlin segment may preferably, but need not necessarily, extend substantially at right angles from one respective end of the purlin base portion. The second purlin segment may preferably, but need not necessarily, extend in a substantially inward direction and substantially at right angles from the first purlin segment.  
      According to an aspect of one preferred embodiment of the invention, the chord base portion of the top chord may preferably, but need not necessarily, securely engage the purlin base portion adjacent to one of the notched portions. The chord base portion may preferably, but need not necessarily, be substantially flush with the purlin base portion. The chord base portion may preferably, but need not necessarily, operatively substantially support the substrate sheathing member.  
      According to an aspect of one preferred embodiment of the invention, the opposing ends of the central chord base portion of the top chord may preferably, but need not necessarily, define a concave portion therebetween. The concave portion may preferably, but need not necessarily, face in the upward direction. According to this aspect of the invention, the apparatus may preferably, but need not necessarily, be adapted to additionally include a predetermined amount of an adhesive operatively interposed in adhering relation substantially between the concave portion and the substrate sheathing member.  
      According to an aspect of one preferred embodiment of the invention, each of the purlin members may preferably, but need not necessarily, be shaped so as to define, substantially adjacent to the notched portions, a substantially “U”-shaped purlin profile that faces in the substantially downward direction. The “U”-shaped purlin profile may preferably, but need not necessarily, include two purlin side portions extending substantially at right angles from opposing ends of the purlin base portion. The first purlin segment may preferably, but need not necessarily, extend beyond the purlin side portions in the downward direction. The purlin side portions may preferably, but need not necessarily, securely engage the chord base portion of the top chord. The purlin side portions may preferably, but need not necessarily, define an up-set portion that extends between each of the notched portions and the purlin base portion. The chord base portion of the top chord may preferably, but need not necessarily, be operatively vertically spaced from the substrate sheathing member.  
      According to an aspect of one preferred embodiment of the invention, each of the web members may preferably, but need not necessarily, be shaped, in profile, so as to define a substantially “C”-shaped web portion.  
      According to an aspect of one preferred embodiment of the invention, the “C”-shaped web portion may preferably, but need not necessarily, include a substantially planar central web base portion and two substantially “L”-shaped web side portions. Each of the web side portions may preferably, but need not necessarily, include a substantially planar first web segment and a substantially planar second web segment. The first web segment may preferably, but need not necessarily, extend substantially at right angles from one respective end of the web base portion. The second web segment may preferably, but need not necessarily, extend in a substantially inward direction and substantially at right angles from the first web segment.  
      According to an aspect of one preferred embodiment of the invention, each of the truss members may preferably, but need not necessarily, additionally include two load distribution plates, each securely engaging the top chord. Each of the load distribution plates may preferably, but need not necessarily, be operatively substantially interposed between a respective one of the support portions and one of the building support members. The load distribution plates may preferably, but need not necessarily, operatively transfer the loads to the building support members preferably, but not necessarily, whilst substantially maintaining local structural integrity of the building support members.  
      According to an aspect of one preferred embodiment of the invention, each of the load distribution plates may preferably, but need not necessarily, be operatively securely fastened to one of the building support members.  
      In accordance with the present invention, there is also disclosed a method of forming a truss and purlin support apparatus for use with building support members. The method includes a chord forming step, a web forming step, and a purlin forming step. In the chord forming step, a plurality of top chords and bottom chords are roll-formed by passing first elongate sheets of light gauge steel material through a series of roll-forming chord tool sets. Passage of the first elongate sheets through each successive one of the chord tool sets progressively forms the top chords and the bottom chords. In the web forming step, a plurality of web members are roll-formed by passing second elongate sheets of light gauge steel material through a series of roll-forming web tool sets. Passage of the second elongate sheets through each successive one of the web tool sets progressively forms the web members. In the purlin forming step, a plurality of purlin members are roll-formed by passing a plurality of third elongate sheets of light gauge steel material through a series of roll-forming purlin tool sets. Passage of the third elongate sheets through each successive one of the purlin tool sets progressively forms the purlin members, such that each of the purlin members has an underside portion that defines a plurality of notched portions that are longitudinally spaced from one another. Each of the web members is adapted to be operatively secured between one of the top chords and one of the bottom chords to form elongate truss members. The truss members are securable on the building support members. The truss members are adapted to be nested and secured within the notched portions of the purlin members. The purlin members operatively extend in a transverse direction relative to the elongate truss members. Each of the purlin members is adapted to operatively support a substantially planar substrate sheathing member thereon.  
      According to an aspect of one preferred embodiment of the invention, the method may preferably, but need not necessarily, additionally include a purlin sheet forming step before the purlin forming step. In the purlin sheet forming step, the plurality of the third elongate sheets may preferably, but need not necessarily, be formed with a plurality of opposed notch pairs along longitudinal edges thereof.  
      According to an aspect of one preferred embodiment of the invention, in the purlin sheet forming step, neighboring ones of the opposed notch pairs may preferably, but need not necessarily, be spaced by a truss on-center distance that is selected from the group consisting of about 36 inches and about 48 inches.  
      According to an aspect of one preferred embodiment of the invention, in the chord forming step, each of the top chords and the bottom chords may preferably, but need not necessarily, be roll-formed so that a chord profile of each of the top chords and the bottom chords defines a substantially “U”-shaped chord portion and two substantially “L”-shaped chord portions. The “U”-shaped chord portion may preferably, but need not necessarily, include two substantially planar chord side portions extending substantially at right angles from opposing ends of a substantially planar central chord base portion. The chord side portions may preferably, but need not necessarily, define a web-receiving aperture therebetween. Each of the “L”-shaped chord portions may preferably, but need not necessarily, include a substantially planar first chord segment and a substantially planar second chord segment. The first chord segment may preferably, but need not necessarily, extend in a substantially outward direction and substantially at right angles from a respective one of the chord side portions. The second chord segment may preferably, but need not necessarily, extend substantially at right angles from the first chord segment. The web-receiving aperture of each of the bottom chords may preferably, but need not necessarily, operatively face in a substantially upward direction and the web-receiving aperture of each of the top chords may preferably, but need not necessarily, operatively face in a substantially downward direction. Each of the web members may preferably, but need not necessarily, be operatively adapted to extend into each web-receiving aperture, and to be secured to each “U”-shaped chord portion, of each of the top chords and the bottom chords.  
      According to an aspect of one preferred embodiment of the invention, in the chord forming step, one or more of the central chord base portion and the chord side portions of each of the top chords and the bottom chords may preferably, but need not necessarily, be roll-formed so as to define a stiffening projection substantially along a longitudinal extent thereof.  
      According to an aspect of one preferred embodiment of the invention, in the chord forming step, a plurality of longitudinally spaced locator apertures may preferably, but need not necessarily, be punched in the chord side portions of each of the top chords and the bottom chords. In the web forming step, a locator aperture mating portion may preferably, but need not necessarily, be punched in each end portion of each of the web members. Each locator aperture mating portion may preferably, but need not necessarily, be adapted to be operatively aligned with one of the locator apertures.  
      According to an aspect of one preferred embodiment of the invention, the method may preferably, but need not necessarily, additionally include a support stiffener forming step. In the support stiffener forming step, a plurality of support stiffening members may preferably, but need not necessarily, be roll-formed by passing the second elongate sheets through the series of roll-forming web tool sets. Passage of the second elongate sheets through each successive one of the web tool sets may preferably, but need not necessarily, progressively form the support stiffening members, such that a support profile of each of the support stiffening members may preferably, but need not necessarily, define a substantially “C”-shaped support stiffening portion. The “C”-shaped support stiffening portion may preferably, but need not necessarily, include two substantially planar support side portions extending substantially at right angles from opposing ends of a substantially planar central support base portion. The web-receiving aperture of each of the top chords may preferably, but need not necessarily, be adapted to operatively receive two support stiffening members therewithin. Each of the support stiffening members may preferably, but need not necessarily, be substantially adjacent to the support portions. The central support base portion may preferably, but need not necessarily, be positioned substantially vertically.  
      According to an aspect of one preferred embodiment of the invention, in the chord forming step, the opposing ends of the central chord base portion of each of the top chords may preferably, but need not necessarily, be roll-formed to define a concave portion therebetween. The concave portion may preferably, but need not necessarily, operatively face in the upward direction. The concave portion may preferably, but need not necessarily, be adapted to operatively receive a predetermined amount of an adhesive.  
      According to an aspect of one preferred embodiment of the invention, in the purlin forming step, each of the purlin members may preferably, but need not necessarily, be roll-formed so as to define, remotely of the notched portions, a substantially “C”-shaped purlin profile that faces in the substantially downward direction.  
      According to an aspect of one preferred embodiment of the invention, in the purlin forming step, the “C”-shaped purlin profile may preferably, but need not necessarily, be roll-formed to include a substantially planar central purlin base portion and two substantially “L”-shaped purlin portions. Each of the “L”-shaped purlin portions may preferably, but need not necessarily, include a substantially planar first purlin segment and a substantially planar second purlin segment. The first purlin segment may preferably, but need not necessarily, extend substantially at right angles from one respective end of the purlin base portion. The second purlin segment may preferably, but need not necessarily, extend in a substantially inward direction and substantially at right angles from the first purlin segment.  
      According to an aspect of one preferred embodiment of the invention, in the purlin forming step, each of the purlin members may preferably, but need not necessarily, be roll-formed so as to define, substantially adjacent to the notched portions, a substantially “U”-shaped purlin profile that faces in the substantially downward direction. The “U”-shaped purlin profile may preferably, but need not necessarily, additionally include two purlin side portions extending substantially at right angles from opposing ends of the purlin base portion. The first purlin segment may preferably, but need not necessarily, extend beyond the purlin side portions in the downward direction. Each of the purlin side portions may preferably, but need not necessarily, define an up-set portion that extends between each of the notched portions and the purlin base portion. The purlin side portions may preferably, but need not necessarily, operatively engage the chord base portion of each of the top chords. The chord base portion of the top chord may preferably, but need not necessarily, be operatively vertically spaced from the substrate sheathing member.  
      According to an aspect of one preferred embodiment of the invention, in the web forming step, each of the web members may preferably, but need not necessarily, be roll-formed so that a web profile of each of the web members defines a substantially “C”-shaped web portion.  
      According to an aspect of one preferred embodiment of the invention, in the web forming step, the “C”-shaped web portion may preferably, but need not necessarily, be roll-formed to include a substantially planar central web base portion and two substantially “L”-shaped web side portions. Each of the web side portions may preferably, but need not necessarily, include a substantially planar first web segment and a substantially planar second web segment. The first web segment may preferably, but need not necessarily, extend substantially at right angles from one respective end of the web base portion. The second web segment may preferably, but need not necessarily, extend in a substantially inward direction and substantially at right angles from the first web segment.  
      In accordance with the present invention, there is additionally disclosed a method of forming a truss and purlin support apparatus on building support members. The method includes a truss assembling step, a truss supporting step after the truss assembling step, an apparatus assembling step, and a sheathing step after the apparatus assembling step. In the truss assembling step, a plurality of elongate truss members may preferably, but need not necessarily, be assembled, each preferably, but not necessarily, having a plurality of support portions longitudinally spaced from one another, and each preferably, but not necessarily, being assembled by locating and securing a plurality of roll-formed web members between a roll-formed top chord and a roll-formed bottom chord. In the truss supporting step, the support portions of the truss members may preferably, but need not necessarily, be located and secured on the building support members. In the apparatus assembling step, the truss members may preferably, but need not necessarily, be nested and secured within a plurality of notched portions of a plurality of roll-formed purlin members. The purlin members may preferably, but need not necessarily, extend in a transverse direction relative to the elongate truss members, so as to preferably, but not necessarily, restrict sliding movement of the purlin members in the transverse direction. In the sheathing step, a substantially planar substrate sheathing member may preferably, but need not necessarily, be supported on the purlin members.  
      According to an aspect of one preferred embodiment of the invention, in the truss supporting step, the centers of gravity of the truss members may preferably, but need not necessarily, be located below the support portions.  
      According to an aspect of one preferred embodiment of the invention, in the apparatus assembling step, neighboring ones of the purlin members may preferably, but need not necessarily, be spaced in a substantially longitudinal direction by a purlin on-center distance that is selected from the group consisting of about 16 inches and about 24 inches.  
      According to an aspect of one preferred embodiment of the invention, in the truss supporting step, two load distribution plates, securely engaging the top chord, may preferably, but need not necessarily, be substantially securely interposed between the support portions and the building support members.  
      According to an aspect of one preferred embodiment of the invention, in the truss supporting step, the load distribution plates may preferably, but need not necessarily, be securely fastened to the building support members.  
      According to an aspect of one preferred embodiment of the invention, in the apparatus assembling step, each of the top chords may preferably, but need not necessarily, be substantially flush with each of the purlin members. In the sheathing step, the top chord may preferably, but need not necessarily, substantially support the substrate sheathing member.  
      According to an aspect of one preferred embodiment of the invention, the method may preferably, but need not necessarily, additionally include a gluing step, before the sheathing step, of applying a predetermined amount of an adhesive preferably, but not necessarily, to one of the substrate sheathing member and a upward-facing concave portion of the top chord. In the sheathing step, the predetermined amount of the adhesive may preferably, but need not necessarily, be operatively interposed in adhering relation substantially between the concave portion and the substrate sheathing member.  
      According to an aspect of one preferred embodiment of the invention, in the apparatus assembling step, up-set portions of the purlin members preferably, but not necessarily, substantially adjacent to the notched portions may preferably, but need not necessarily, engage each the top chord. In the sheathing step, the top chord may preferably, but need not necessarily, be vertically spaced from the substrate sheathing member.  
      Other advantages, features and characteristics of the present invention, as well as methods of operation and functions of the related elements of the structure, and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following detailed description and the appended claims with reference to the accompanying drawings, the latter of which are briefly described hereinbelow.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  of the drawings appended hereto is a top perspective view of a prior art floor system;  
       FIG. 2  is an enlarged view of encircled area  2  of  FIG. 1 ;  
       FIG. 3  of the drawings is a top perspective view of a floor support apparatus according to the present invention;  
       FIG. 3A  is an enlarged top perspective view of a portion of the floor support apparatus of  FIG. 3 ;  
       FIG. 4  of the drawings is a top perspective view of another floor support apparatus according to the present invention;  
       FIG. 5  is a top perspective view of a portion of one of the truss members shown in  FIG. 3 ;  
       FIG. 6  is an enlarged view of encircled area  6  of  FIG. 5 ;  
       FIG. 7  is a top perspective view of a portion of one of the top chords shown in  FIG. 5 ;  
       FIG. 8  is a top perspective view of one of the web members shown in  FIG. 5 ;  
       FIG. 8A  is a top perspective view of a support stiffening member shown in  FIG. 5 ;  
       FIG. 9  is a top front perspective view of one of the floor purlin members shown in  FIG. 3 ;  
       FIG. 10  is a top front perspective view of a roof purlin member of a roof support apparatus according to the invention;  
       FIG. 11  is a top perspective view of a low rise hotel installation of the floor support apparatus of  FIG. 3 ;  
       FIG. 12  is a top perspective view of a roof support apparatus according to the invention;  
       FIG. 13  is a top perspective view of portions of a top chord and a roof purlin member shown in  FIG. 12 ;  
       FIG. 14  of the drawings is a front view of the top chord of  FIG. 7 ;  
       FIG. 15  of the drawings is a front sectional view of the floor sheathing and one of the top chords shown in  FIG. 3 ;  
       FIG. 16  is a top rear perspective view of the roof purlin member of  FIG. 10 ;  
       FIG. 17  is a top rear perspective view of the floor purlin member of  FIG. 9 ;  
       FIG. 18  of the drawings is a top view of a portion of a light gauge steel sheet used in roll-forming the floor purlin member of  FIG. 9 ; and  
       FIG. 19  is a side view of a corresponding portion of a floor purlin member roll-formed from the sheet shown in  FIG. 18 ; 
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT  
      A truss and purlin support apparatus  40  according to the invention in shown in  FIG. 3  of the drawings in use with building support members  20  and substantially planar substrate sheathing members  26 . The apparatus  40  includes a plurality of Pratt-style elongate truss members  50  and a plurality of purlin members  120 .  
      Each of the truss members  50  has at least two support portions  52  longitudinally spaced from one another. The support portions  52  are adapted to operatively engage and transfer loads to the building support members  20 .  
      Each of the truss members  50  includes an elongate top chord  54   b , an elongate bottom chord  54   a , and a plurality of web members  80  securely extending between the top chord  54   b  and the bottom chord  54   a . The top chord  54   b , the bottom chord  54   a , the web members  80 , and the purlin members  120  are preferably constructed from roll-formed light gauge steel material. Each top chord  54   b  and each bottom chord  54   a  may preferably, but need not necessarily, be shaped, in profile, so as to define a substantially “U”-shaped chord portion  56  and two substantially “L”-shaped chord portions  72 .  
      The “U”-shaped chord portion  56  may preferably, but need not necessarily, include two substantially planar chord side portions  64  extending substantially at right angles from opposing ends  60  of a substantially planar central chord base portion  58 . The chord side portions  64  may preferably, but need not necessarily, define a web-receiving aperture  66  therebetween.  
      One or more of the central chord base portion  58  and the chord side portions  64  of each top chord  54   b  and each bottom chord  54   a  may preferably, but need not necessarily, be shaped so as to define a stiffening projection  68  substantially along a longitudinal extent thereof, whereby each top chord  54   b  and each bottom chord  54   a  may preferably, but need not necessarily, be provided with structural rigidity.  
      In each top chord  54   b  and in each bottom chord  54   a , the chord side portions  64  may preferably, but need not necessarily, be shaped so as to define a plurality of longitudinally spaced locator apertures  70  therein.  
      Each of the “L”-shaped chord portions  72  may preferably, but need not necessarily, include a substantially planar first chord segment  74  and a substantially planar second chord segment  76 . The first chord segment  74  may preferably, but need not necessarily, extend in a substantially outward direction “D” and substantially at right angles from a respective one of the chord side portions  64 . The second chord segment  76  may preferably, but need not necessarily, extend substantially at right angles from the first chord segment  74 .  
      In each of the truss members  50 , the web-receiving aperture  66  of the bottom chord  54   a  may preferably, but need not necessarily, face in a substantially upward direction “F” and the web-receiving aperture  66  of the top chord  54   b  may preferably, but need not necessarily, face in a substantially downward direction “G”. Each of the web members  80  may preferably, but need not necessarily, extend into and be located within each web-receiving aperture  66 , and securely engage each “U”-shaped chord portion  56 , of the top chord  54   b  and of the bottom chord  54   a.    
      As best seen in  FIG. 8 , each of the web members  80  may preferably, but need not necessarily, be provided with end portions that are each shaped to define a locator aperture mating portion  84 . Each locator aperture mating portion  84  may preferably, but need not necessarily, be substantially securely aligned with one of the locator apertures  70  by web fasteners (not shown).  
      Each of the web members  80  may preferably, but need not necessarily, be shaped, in profile, so as to define a substantially “C”-shaped web portion  86 . The “C”-shaped web portion  86  may preferably, but need not necessarily, include a substantially planar central web base portion  88  and two substantially “L”-shaped web side portions  90 . Each of the web side portions  90  may preferably, but need not necessarily, include a substantially planar first web segment  92  and a substantially planar second web segment  94 . The first web segment  92  may preferably, but need not necessarily, extend substantially at right angles from one respective end of the web base portion  88 . The second web segment  94  may preferably, but need not necessarily, extend in a substantially inward direction “E” and substantially at right angles from the first web segment  92 .  
      Each of the truss members  50  may preferably, but need not necessarily, have a center of gravity (not shown) that is operatively located below the support portions  52 .  
      Each of the truss members  50  may preferably, but need not necessarily, additionally include two support stiffening members  100 , each preferably, but not necessarily, securely engaging the top chord  54   b  substantially adjacent to a respective one of the support portions  52 . Each of the support stiffening members  100  may preferably, but need not necessarily, be positioned within the web-receiving aperture  66  of the top chord  54   b . The support stiffening members  100  may preferably, but need not necessarily, substantially maintain local structural integrity of the support portions  52  preferably, but not necessarily, whilst the support portions  52  operatively transfer the loads to the building support members  20 .  
      Each of the support stiffening members  100  (as best seen in  FIG. 8A ) may preferably, but need not necessarily, be shaped, in profile, so as to define a substantially “C”-shaped support stiffening portion  102 . The “C”-shaped support stiffening portion  102  may preferably, but need not necessarily, include two substantially planar support side portions  108  extending substantially at right angles from opposing ends  106  of a substantially planar central support base portion  104 . The central support base portion  104  may preferably, but need not necessarily, be positioned substantially vertically within the web-receiving aperture  66  of the top chord  54   b  (as best seen in  FIG. 6 ).  
      Each of the truss members  50  may preferably, but need not necessarily, additionally include two load distribution plates  110 , each securely engaging the top chord  54   b . Each of the load distribution plates  110  may preferably, but need not necessarily, be operatively substantially interposed between a respective one of the support portions  52  and one of the building support members  20 . The load distribution plates  110  may preferably, but need not necessarily, operatively transfer the loads to the building support members  20  preferably, but not necessarily, whilst substantially maintaining local structural integrity of the building support members  20 . Each of the load distribution plates  110  may preferably, but need not necessarily, be operatively securely fastened, through fastening apertures  112 , to one of the building support members  20 .  
      Each of the purlin members  120  extends in a substantially transverse direction “B” relative to the elongate truss members  50 . Each of the purlin members  120  has an underside portion  124  that is shaped to define a plurality of notched portions  126 . The notched portions  126  may extend to end portions  122  of the purlin members  120   
      The notched portions  126  are spaced from one another in the transverse direction “B” along the underside portion  124 . Each of the notched portions  126  is saddled over a respective top chord  54   b  of the truss members  50 , so as to restrict sliding movement of the purlin members  120  in the transverse direction “B”.  
      Each of the purlin members  120  may preferably, but need not necessarily, be shaped so as to define, remotely of the notched portions  126 , a substantially “C”-shaped purlin profile  132  that faces in the substantially downward direction “G”.  
      The “C”-shaped purlin profile  132  may preferably, but need not necessarily, be defined by a substantially planar central purlin base portion  134  and two substantially “L”-shaped purlin portions  136 . Each of the “L”-shaped purlin portions  136  may preferably, but need not necessarily, include a substantially planar first purlin segment  138  and a substantially planar second purlin segment  140 . The first purlin segment  138  may preferably, but need not necessarily, extend substantially at right angles from one respective end of the purlin base portion  134 . The second purlin segment  140  may preferably, but need not necessarily, extend in a substantially inward direction “E” and substantially at right angles from the first purlin segment  138 .  
      As best seen in  FIG. 3A , neighboring ones of the truss members  50  may preferably, but need not necessarily, be spaced by a truss on-center distance “J” in the substantially transverse direction “B” that is selected from the group consisting of about 36 inches and about 48 inches. Similarly, neighboring ones of the purlin members  120  may preferably, but need not necessarily, be spaced by a purlin on-center distance “K” in a substantially longitudinal direction “A” that is selected from the group consisting of about 16 inches and about 24 inches.  
      The purlin members  120  operatively support the substrate sheathing member  26  thereon.  
      In floor systems, the chord base portion  58  of the top chord  54   b  may preferably, but need not necessarily, securely engage the purlin base portion  134  adjacent to one of the notched portions  126 . In such floor systems, the chord base portion  58  may preferably, but need not necessarily, be substantially flush with the purlin base portion  134 . In floor systems, the chord base portion  58  may preferably, but need not necessarily, operatively substantially support the substrate sheathing member  26 .  
      As best seen in  FIG. 15 , the opposing ends  60  of the central chord base portion  58  of the top chord  54   b  may preferably, but need not necessarily, define a concave portion  62  therebetween. The concave portion  62  may preferably, but need not necessarily, face in the upward direction “F”. The apparatus  40  may preferably, but need not necessarily, be adapted to additionally include a predetermined amount  152  of an adhesive  150  operatively interposed in adhering relation substantially between the concave portion  62  and the substrate sheathing member  26 .  
      Alternately, and as may be particularly advantageous in the construction of roof systems according to the present invention, each of the purlin members  120  may preferably, but need not necessarily, be shaped so as to define, substantially adjacent to the notched portions  126 , a substantially “U”-shaped purlin profile  142  that faces in the substantially downward direction “G”. The “U”-shaped purlin profile  142  may preferably, but need not necessarily, include two purlin side portions  144  extending substantially at right angles from opposing ends of the purlin base portion  134 . The first purlin segment  138  may preferably, but need not necessarily, extend beyond the purlin side portions  144  in the downward direction “G”. The purlin side portions  144  may preferably, but need not necessarily, securely engage the chord base portion  58  of the top chord  54   b . The purlin side portions  144  may preferably, but need not necessarily, define an up-set portion (with the terms “purlin side portion” and “up-set portion” being herein used, mutatis mutandis, substantially interchangeably) that extends between each of the notched portions  126  and the purlin base portion  134 . In roof systems constructed according to the present invention, the chord base portion  58  of the top chord  54   b  may preferably, but need not necessarily, be operatively vertically spaced from the substrate sheathing member  26 .  
      The present invention also extends to a method of forming the apparatus  40  which may preferably include a chord forming step, a web forming step, a support stiffener forming step, a purlin sheet forming step, and a purlin forming step.  
      In the chord forming step, the top chords  54   b  and the bottom chords  54   a  are roll-formed by passing first elongate sheets (not shown) of light gauge steel material through a series of roll-forming chord tool sets (not shown). Passage of the first elongate sheets through each successive one of the chord tool sets progressively forms the top chords  54   b  and the bottom chords  54   a . In the chord forming step, each of the top chords  54   b  and the bottom chords  54   a  may preferably, but need not necessarily, be roll-formed so that a chord profile of each of the top chords  54   b  and the bottom chords  54   a  defines the “U”-shaped chord portion  56  and the two “L”-shaped chord portions  72 . One or more of the central chord base portion  58  and the chord side portions  64  of each of the top chords  54   b  and the bottom chords  54   a  may preferably, but need not necessarily, be roll-formed so as to define a stiffening projection  68  substantially along a longitudinal extent thereof. The locator apertures  70  may preferably, but need not necessarily, be punched in the chord side portions  64  of each of the top chords  54   b  and the bottom chords  54   a . In the chord forming step, the opposing ends  60  of the central chord base portion  58  of each of the top chords  54   b  may preferably, but need not necessarily, be roll-formed to define the concave portion  62  therebetween.  
      In the web forming step, the web members  80  are roll-formed by passing second elongate sheets (not shown) of light gauge steel material through a series of roll-forming web tool sets (not shown). Passage of the second elongate sheets through each successive one of the web tool sets progressively forms the web members  80 . In the web forming step, a locator aperture mating portion  84  may preferably, but need not necessarily, be punched in each end portion  82  of each of the web members  80 .  
      In the support stiffener forming step, the support stiffening members  100  may preferably, but need not necessarily, be roll-formed by passing the second elongate sheets through the series of roll-forming web tool sets. Passage of the second elongate sheets through each successive one of the web tool sets may preferably, but need not necessarily, progressively form the support stiffening members  100 , such that a support profile  102  of each of the support stiffening members  100  may preferably, but need not necessarily, define the substantially “C”-shaped support stiffening portion (with the terms “support profile” and “support stiffening portion” being herein used, mutatis mutandis, substantially interchangeably).  
      In the purlin sheet forming step, the plurality of third elongate sheets  200  (as shown in  FIG. 18 ) may preferably, but need not necessarily, be formed with a plurality of opposed notch pairs  204  along longitudinal edges  202  thereof. In the purlin sheet forming step, neighboring ones of the opposed notch pairs  204  may preferably, but need not necessarily, be spaced by a truss on-center distance “J” that is selected from the group consisting of about 36 inches and about 48 inches.  
      In the purlin forming step, the purlin members  120  are roll-formed by passing the third elongate sheets  200  (as shown in  FIG. 18 ) of light gauge steel material through a series of roll-forming purlin tool sets (not shown). Passage of the third elongate sheets  200  through each successive one of the purlin tool sets progressively forms the purlin members  120 , such that each of the purlin members  120  has the underside portion  124  that defines the notched portions  126 .  
      According to this method, each of the web members  80  so formed is adapted to be operatively secured between one of the top chords  54   b  and one of the bottom chords  54   a  to form the elongate truss members  50 . Each of the web members  80  may preferably, but need not necessarily, be operatively adapted to extend into each web-receiving aperture  66 , and to be secured to each “U”-shaped chord portion  56 , of each of the top chords  54   b  and the bottom chords  54   a . Each locator aperture mating portion  84  may preferably, but need not necessarily, be adapted to be operatively aligned with one of the locator apertures  70  and secured therewith by a web fastener (not shown). The web-receiving aperture  66  of each of the top chords  54   b  may preferably, but need not necessarily, be adapted to operatively receive two support stiffening members  100  therewithin. Each of the support stiffening members  100  may preferably, but need not necessarily, be substantially adjacent to the support portions  52 . The central support base portion  104  may preferably, but need not necessarily, be positioned substantially vertically. The truss members  50  are securable on the building support members  20 . The truss members  50  are adapted to be nested and secured within the notched portions  126  of the purlin members  120 . The purlin members  120  operatively extend in the transverse direction “B” relative to the elongate truss members  50 . Each of the purlin members  120  is adapted to operatively support the sheathing member  26  thereon.  
      The present invention additionally extends to a method of using the apparatus  40  with the building support members  20 . This method includes a truss assembling step, a truss supporting step after the truss assembling step, an apparatus  40  assembling step, a gluing step, and a sheathing step after the apparatus  40  assembling step.  
      In the truss assembling step, the truss members  50  may preferably, but need not necessarily, be assembled, each preferably, but not necessarily, having the support portions  52  longitudinally spaced from one another, and each preferably, but not necessarily, being assembled by locating and securing the web members  80  between the top chord  54   b  and the bottom chord  54   a.    
      In the truss supporting step, the support portions  52  of the truss members  50  may preferably, but need not necessarily, be located and secured on the building support members  20 . The centers of gravity of the truss members  50  may preferably, but need not necessarily, be located below the support portions  52 . In the truss supporting step, the load distribution plates  110 , securely engaging the top chord  54   b , may preferably, but need not necessarily, be substantially securely interposed between the support portions  52  and the building support members  20 . The load distribution plates  110  may preferably, but need not necessarily, be securely fastened, through fastening apertures  112 , to the building support members  20 .  
      In the apparatus  40  assembling step, the truss members  50  may preferably, but need not necessarily, be nested and secured within the notched portions  126  of the purlin members  120 . The purlin members  120  may preferably, but need not necessarily, extend in the transverse direction “B” relative to the elongate truss members  50 , so as to preferably, but not necessarily, restrict sliding movement of the purlin members  120  in the transverse direction “B”. Neighboring ones of the purlin members  120  may preferably, but need not necessarily, be spaced in the longitudinal direction “A” by the purlin on-center distance “K” being selected from the group consisting of about 16 inches and about 24 inches.  
      In the apparatus  40  assembling step, for floor systems, each of the top chords  54   b  may preferably, but need not necessarily, be substantially flush with each of the purlin members  120 .  
      In the apparatus  40  assembling step, for roof systems, the up-set portions  144  of the purlin members  120 —preferably, but not necessarily, substantially adjacent to the notched portions  126 —may preferably, but need not necessarily, engage each top chord  54   b.    
      In the gluing step, for floor systems, the predetermined amount  152  of the adhesive  150  may preferably, but need not necessarily, be applied to one of the substrate sheathing member  26  and a upward-facing concave portion  62  of the top chord  54   b.    
      In the sheathing step, the sheathing member  26  may preferably, but need not necessarily, be supported on the purlin members  120 .  
      In the sheathing step, for floor systems, the top chord  54   b  may preferably, but need not necessarily, substantially support the substrate sheathing member  26 . The predetermined amount  152  of the adhesive  150  may preferably, but need not necessarily, be operatively interposed in adhering relation substantially between the concave portion  62  and the substrate sheathing member  26 .  
      In the sheathing step, for roof systems, the top chord  54   b  may preferably, but need not necessarily, be vertically spaced from the substrate sheathing member  26 .  
      The construction of the truss members  50  according to the present invention is shown in  FIG. 3 , and are shown adjacent to the building support members  20 .  FIG. 3  shows the truss members  50  in use with the floor system. The truss members  50  have the purlin members  120  saddled on top. The sheathing member  26  (i.e., floor sheathing) is laid on top of the truss members  50  and the purlin members  120 . The truss member  50  is a Pratt-style truss member that is supported on the building support members  20  in a manner that may be best seen in  FIGS. 5 and 6 . The truss member  50  includes bottom and top chords  54   a ,  54   b  of substantially the same profile, as well as the web members  80 , which have a “C”-shaped web profile  86 . The apparatus  40  also includes the load distribution plates  110  with pre-drilled fastening apertures  112 , and support stiffening members  100  which may preferably each take the form of a short up-right piece of webbing having substantially the same profile  102  as the “C”-shaped web profile  86 . All elements may preferably be either of welded construction, and/or be screwed together, and/or be fastened by way of alternate fasteners, such as, for example, insert rivets. The bottom and top chords  54   a ,  54   b  and the web members  80  are provided with the locator apertures  70  and the locator aperture mating portions  84 , respectively, which are used to locate the positions of the web members  80  relative to the top and bottom chords  54   a ,  54   b.    
      The load distribution plates  110  may help to ensure loads are transferred to supporting structures below the building support members  20  without substantial localized distortion, and the support stiffening members  100  may help to prevent the top chord  54   b  from local collapse as a result of point loads.  
      The apparatus  40 , including the truss members  50 , is an open-web assembly. The apparatus  40  is shown in a floor configuration in  FIGS. 3 and 3 A, where the truss members  50  may preferably be spaced from one another by the truss on-center distance (as indicated generally by arrow “J” in  FIG. 3A ) of about 32″ or about 48″. As may be best appreciated by a person having ordinary skill in the art upon a consideration of  FIG. 3A , the Pratt-style top chord  54   b  has an inherent resistance to toppling and/or falling over under concentrated loads, since its center of gravity (not shown) is below the support portions  52 .  
      In floor systems, and as best seen in  FIG. 3A , the truss members  50  according to the present invention may span from the building support member  20  (alternately referred to hereinafter as a “party wall”) to the party wall  20  in an alternating sequence upon the building support members  20 . To accommodate this, it may have been generally thought, though it is not essential to the working of the present invention, that each of the truss members  50  may need to carry about twice the normal spans and therefore twice the loads. It may have been traditionally thought, though again not essential to the working of the present invention, that with the installation of ⅝″ thick or ¾″ thick sheathing members  26 , the maximum distance between sheathing support points thereunder should not exceed about 16″ or about 24″, respectively. According to the present invention, by positioning the truss members  50  at about double the usual spacing, the wall floor junction and bearing support problems may be overcome. To provide the desired level of comfort concerning whether adequate support is provided for the sheathing member  26  (hereinafter, alternately referred to at the “sub-floor”), the purlin members  120 , having the underside portions  124  with the notched portions  126  spaced therealong, are placed on top of the truss embers  50 , with the top chords  54   b  thereof nesting in the notched portions  126 . These purlin members  120  (hereinafter, alternately referred to as “notched purlins”) are shown in detail, inter alia, in  FIGS. 9 and 10 .  
      Also, though only the top chord  54   b  is shown in detail in  FIG. 7 , it should be appreciated that the bottom chord  54   a  may preferably have a substantially identical profile. The top chord  54   b  (e.g., as shown in  FIG. 7 ) may preferably include, among other things, the two “L”-shaped chord portions  72 , the stiffening projections  68 , and the locator apertures  70  which are used to position the web members  80  within the top and bottom chords  54   a ,  54   b.    
      The notched purlins  120  have the “C”-shaped purlin profile  132  and may preferably be placed structurally in their weakest axis against loads (not shown) to avoid and/or reduce an otherwise tendency to twist. Though not essential to the working of the invention, it is generally thought, that with the notched purlins  120  placed in their weakest axis against the loads, the shear center may run substantially directly inline with the load, such that there may be a reduced tendency for the LGS member to twist. The purlin members  120  according to the invention will preferably be sufficiently rigid to support the sub-floor sheathing  26 . In  FIG. 3A , the notched purlins  120  are shown in position over the truss members  50 , and may preferably be spaced from one another by the purlin on-center distance (as indicated generally by arrow “K”) of about 16″ or about 24″.  
      The purlin member  120  which is used in floor systems (i.e., the floor purlin member  120   a  best seen in  FIG. 19 ) is fastened onto the top chord  54   b  by a purlin fastener  130  extending through a fastening aperture  128  in the purlin base portion  134 . The floor purlin member  120   a  (such as that shown in  FIG. 17 ) may be substantially flat adjacent the notched portions  126 , contributing substantially little or no structural strength in vertical loadings. This flatness may help to avoid creating a bump over the top chord  54   b , but may or may not be necessary due to its intended use with features inherent in the sub-floor  26 . The notched purlins  120  provide the necessary support over the otherwise unsupported length “J” of 32″ or 48″, notwithstanding the flat element directly connecting to the top chord  54   b.    
      According to one aspect of the present invention, the truss members  50  may preferably be supported at the support portions  52  that are located either on the top chord  54   b  or substantially adjacent thereto. Such a configuration allows the truss member  50  to “hang” so as to inherently reduce the chances of collapse under load conditions and so as to greatly reduce the secondary installation work that might otherwise be required in order to stabilize the floor system.  
      By spacing the truss members  50  twice the distance apart from one another, the present invention may provide one or more significant advantages over prior art systems—possibly making it easier to install HVAC (heating and air conditioning) components, as well as electrical and plumbing components. With the truss members being spaced the distance “J” from one another of 48″ on-centers (hereinafter, alternately referred to as “OC”), and with wall studs being spaced from one another at about 16″ OC, then in comparison to prior systems, two of every three prior floor trusses may not be required.  
      It may be additionally thought, though it is not essential to the working of the present invention, that the amount of deflection of the floor truss members  50  may be substantially dependent upon the modulus of elasticity for steel, Young&#39;s modulus (i.e., with E approximately equal to about 29,500,000 psi), which may be much higher for steel than for wood. The comparatively low modulus of elasticity for wood may mean that a typical 10″ wood floor joist may deflect vastly more than one formed from LGS. Various governmental codes and standards may limit the acceptable amount of deflection for the truss member  50  under the load (not shown) to the unsupported spanning length (in inches) divided by 360. As a result, it may not be possible, for example, to provide double spans for most wood applications. As such, the concepts employed, and the functioning and utilities afforded, by the LGS construction of the present invention do not work the same way for, and do not have a historical equivalent in, wood applications.  
      Various features and capabilities of, and/or advantages afforded by, the present invention—e.g., alternating spacing of the truss members  50  as shown in  FIG. 3A , supporting the truss members  50  by the top chords  54   b  on the building support members  20 , forming the apparatus  40  from open-web truss members  50  and notched purlins  120 —are not present, either on their own or in combination with one another, in the prior art relating to the construction industry, and their use in floor and roof construction may preferably yield considerable cost savings and/or other great advantages over wood floor joist constructions.  
      A typical low rise hotel installation (e.g., about six building stories) according to the present invention is shown in  FIG. 11 , where the walls  24  can be seen to divide the structure into first  25   a , second  25   b , and third  25   c  rooms.  
      One advantage of the apparatus  40 , with the notched purlins  120 , may be that the notched portions  126  may be generally provided at the distance “J” of either 32″ or 48″ apart. Accordingly, the notched portions  126  may preferably be used as a template for measuring the location and distance between adjacent ones of the floor truss members  50 . As such, in use, one may generally need only to locate a starting point, after which the measuring tape may be no longer required until completion of the unit  25   a ,  25   b ,  25   c.    
      The “hat”-shaped design of the bottom and top chords  54   a ,  54   b , which is best seen  FIGS. 7, 14  and  15 , may be relatively easy to fabricate and/or install. Such “hat”-shaped top chords  54   b  have not previously been used with notched purlins  120 , and such use may results in many benefits.  
      A further feature of the top chord  54   b , which may be particularly useful when used in floor systems, is that base portion  58  of the top chord  54   b  includes a concave portion  62  (as best seen in  FIGS. 14 and 15 ). The concave portion  62  is defined between opposing ends  60  of the base portion  58  and faces in the upward direction (as indicated generally by arrow “F” in  FIG. 14 ). Through use of the concave portion  62 , a user may control the thickness of the adhesive  150  (e.g., glue) that is applied. Typically, as shown in  FIG. 15 , the sub-floor  26  must be glued as well as screwed to the top chord  54   b  by a sheathing fastener  28  extending through a chord base aperture  63  in the chord base portion  58 . The glue  150  may help to reduce squeaking that might otherwise be caused by movement of the sub-flooring  26  and the surface where the bond is applied. The ability to control glue thickness, so that the predetermined amount  152  of the adhesive  150  is applied, helps to increase the chances that a minimum amount of the glue  150  may be applied—i.e., as it might otherwise be squeezed out leaving no glue between the surfaces.  
      As may be appreciated by persons having ordinary skill in the art upon a consideration of  FIG. 15 , the use of the notched purlins  120  may help to provide improved (i.e., reduced) sound transmission characteristics underneath the floor sheathing  26 .  
      When used in roof systems, the notched purlins  120  (alternately herein referred to as roof purlin members  120   b  when used in such roof systems) as shown in  FIGS. 12, 13  and  16  may preferably include the up-set portion  144 . This feature may allow flow of air between the roof sheathing elements (not shown) and the top chord  54   b  so as to reduce the likelihood that moisture may become trapped.  
      As shown in  FIG. 12 , the roof system includes top chords  54   b , bottom chords  54   a , and web members  80 . In prior art roof systems, the truss members may heretofore have been spaced at about 24″ OC in order to comply with the maximum allowable unsupported span for a typical plywood or OSB board sheathing material. The top chords  54   b  in a roof system constructed according to the invention, however, may preferably be spaced at 48″ OC with notched purlins  120   b  being spaced at 24″ OC whilst still providing the desired level of support for the roof sheathing (not shown). Such a construction according to the present invention may save about ½ of the normal trusses which might otherwise have been installed according to the prior art.  
      In  FIG. 13 , the roof purlin member  120   b  is shown with the up-set portion  144  being in the approximate order of about ⅞″. Though not essential to the working of the present invention, it may be generally believed that such an up-set portion  144  may help to improve air circulation in the roof and to reduce the likelihood of moisture entrapment.  
      Various other modifications and alterations may be used in the design and manufacture of the truss and purlin support apparatus and in the method of making and using same with building supports and floor and roof sheathing according to the present invention without departing from the spirit and scope of the invention, which is limited only by the accompanying claims.