Roof joist for modular building and methods

Abstract

A roof joist for a roof section of a modular building having an interior ceiling with a length, having an upper chord, central chord, and lower chord. The lower chord comprises: (i) a top chord segment joined to, and parallel with, the central chord; (ii) a pair of sidewall chord segments that oppose one another and extend parallel to the top chord segment; and (iii) a pair of outer flanges that extend outwardly from the sidewall chord segments to support the interior ceiling. A pair of inner flanges can also extend inwardly from the sidewall chord segments to support fixtures in the interior of the building.

1 . A roof joist for a roof section of a modular building, the modular building having an interior ceiling with a length, and the roof joist comprising:
 (a) an upper chord comprising a length sufficiently long to extend substantially across the entire length of the interior ceiling of the roof section of the modular building;   (b) a central chord joined to the upper chord; and   (c) a lower chord joined to the central chord, the lower chord comprising:
 (i) a top chord segment; 
 (ii) first and second sidewall chord segments that extend downwardly from the top chord segment and oppose one another; and 
 (iii) first and second outer flanges that extend outwardly from the first and second sidewall chord segments, respectively, the flanges being capable of supporting the interior ceiling. 
   
   
   
       2 . A roof joist according to  claim 1  wherein the upper chord comprises a longitudinal and planar beam. 
   
   
       3 . A roof joist according to  claim 2  wherein the central chord comprises a flat beam that is perpendicular to the longitudinal and planar beam of the upper chord. 
   
   
       4 . A roof joist according to  claim 2  wherein central chord comprises two opposing sidewall members that are parallel to one another. 
   
   
       5 . A roof joist according to  claim 1  wherein the upper chord comprises a first longitudinal hollow channel having a first enclosed volume. 
   
   
       6 . A roof joist according to  claim 5  wherein the central chord comprises two opposing sidewall members that are parallel to one another and define a second longitudinal hollow channel having a second enclosed volume, and wherein the second enclosed volume is sized larger than the first enclosed volume. 
   
   
       7 . A roof joist according to  claim 6  wherein the first and second enclosed volumes each comprise a rectangular cross-section. 
   
   
       8 . A roof joist according to  claim 1  further comprising first and second inner flanges that extend inwardly from the first and second sidewall chord segments, respectively. 
   
   
       9 . A roof joist according to  claim 8  wherein a length of each of the first and second inner flanges of the lower chord is smaller than a length of an outer flange. 
   
   
       10 . A roof joist according to  claim 9  wherein each outer flange is sized from about 2 to about 4 cm. 
   
   
       11 . A roof joist according to  claim 9  wherein each inner flange is sized from about 1 to about 3 cm. 
   
   
       12 . A roof joist according to  claim 8  wherein each inner flange comprises an inner ridge. 
   
   
       13 . A modular building comprising a roof section defined by a plurality of the roof joists of  claim 1 , a ceiling supported by the roof joists, sidewalls, and a support sled. 
   
   
       14 . A method of forming a roof joist for a roof section of a modular building having an interior ceiling with a length, the method comprising:
 (a) extruding a material to form an extrusion preform comprising an upper chord, a central chord joined to the upper chord, and a lower chord joined to the central chord, the lower chord comprising:
 (i) a top chord segment; 
 (ii) first and second sidewall chord segments that extend downwardly from the top chord segment and oppose one another; and 
 (iii) first and second outer flanges that extend outwardly from the first and second sidewall chord segments, respectively, the flanges being capable of supporting the interior ceiling; and 
   (b) cutting the extrusion preform when the lengths of the upper, central and lower chords are each sufficiently long to extend substantially across the entire length of the interior ceiling of the roof section of the modular building.   
   
   
       15 . A method according to  claim 14  wherein the material comprises a metal. 
   
   
       16 . A method according to  claim 15  wherein the metal comprises steel, aluminum, iron, tin, or alloys thereof. 
   
   
       17 . A method according to  claim 14  wherein the material comprises a polymer or composite material. 
   
   
       18 . A method according to  claim 14  wherein the material comprises a reinforced composite material.