Patent Publication Number: US-2007094945-A1

Title: Fire resistant construction

Description:
BACKGROUND OF THE INVENTION  
      (1) Field of the Invention  
      The present invention relates generally to a structure having a fire resistance rated, area separation wall and, more particularly, to a two-hour fire resistance rated, area separation wall for a structure including an interior support structure; only an outer membrane on each side of said interior support structure; and a substantially organic thermal insulation barrier between the outer membranes.  
      (2) Description of the Prior Art  
      Multi-family residential constructions typically include a separation wall constructed of wood members and having an insulating material between the units. These wood members may include dual two-by-four framing with a drywall surface on both sides of the framing. In most cases, this type of construction requires that the drywall be attached to the interior surface of the framing before the framing is placed upright to serve as a wall. After the framing is placed upright, insulation material may be positioned in the framing, and later an additional drywall membrane is fastened to the outside of the framing to complete an interior wall. This process is expensive, labor-intensive and time consuming.  
      One purpose of such a dual membrane construction of an area separation wall is to provide a fire resistance separation between adjacent spaces to meet federal, state and local regulations concerning the fire resistance of such a construction. Underwriters Laboratories Inc. (UL), an independent, not-for-profit product safety testing and certification organization, has been testing products for public safety for more than a century. Because UL has an undisputed reputation as the leader in U.S. product safety and certification, it is advantageous to obtain classification of a building product by UL. One UL test, ANSI/UL 263 (ASTM E119 and NFPA 251), involves rating such a separation wall for fire resistance. If a separation wall including only an outer membrane could be developed that is sufficiently fire resistant to gain UL classification for two-hour fire resistance, such a separation wall would be less costly to construct than conventional separation wall.  
      Thus, there is a need for a structure having a fire resistance rated, area separation wall, the structure including a first and second building units and a two- hour fire resistance rated, area separation wall having only outer membranes.  
     SUMMARY OF THE INVENTION  
      The present invention is directed to a structure having a fire resistance rated, area separation wall including: a first building unit; a second building unit; and a two- hour fire resistance rated, area separation wall having only outer membranes. In the preferred embodiment, the two-hour fire resistance rated, area separation wall includes: (a) an interior support structure; (b) only an outer membrane on each side of the interior support structure; and (c) a substantially organic thermal insulation barrier between the outer membranes. Also, in the preferred embodiment, the structure having a fire resistance rated, area separation wall may include a tying structure connecting the fire resistance rated, area separation wall to the first unit and the second unit.  
      Accordingly, one aspect of the present invention is to provide a structure having a fire resistance rated, area separation wall including: a first building unit; a second building unit; and a two-hour fire resistance rated, area separation wall having only outer membranes.  
      Another aspect of the present invention is to provide a two-hour fire resistance rated, area separation wall for a structure including: an interior support structure; only an outer membrane on each side of the interior support structure; and a substantially organic thermal insulation barrier between the outer membranes.  
      Still another aspect of the present invention is to provide a structure having a fire resistance rated, area separation wall, the structure including: a first building unit; a second building unit; and a two-hour fire resistance rated, area separation wall having only outer membranes, The area separation wall including: (a) an interior support structure; (b) only an outer membrane on each side of the interior support structure; and (c) a substantially organic thermal insulation barrier between the outer membranes; and a tying structure connecting the fire resistance rated, area separation wall to the first unit and the second unit.  
      These and other aspects of the present invention will become apparent to those skilled in the art after a reading of the following description of the preferred embodiment when considered with the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       FIG. 1  is a front perspective view of a structure having a fire resistance rated, area separation wall constructed according to the present invention;  
       FIG. 2  is a side view of the two-hour fire resistance rated, area separation wall for a structure shown in  FIG. 1  including a tying structure; and  
       FIG. 3  is a side view of the two-hour fire resistance rated, area separation wall for a structure shown in  FIG. 1  without a tying structure 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      In the following description, like reference characters designate like or corresponding parts throughout the several views. Also in the following description, it is to be understood that such terms as “forward,” “rearward,” “left,” “right,” “upwardly,” “downwardly,” and the like are words of convenience and are not to be construed as limiting terms.  
      Referring now to the drawings in general and  FIG. 1  in particular, it will be understood that the illustrations are for the purpose of describing a preferred embodiment of the invention and are not intended to limit the invention thereto. As best seen in  FIG. 1 , a structure having a fire resistance rated, area separation wall, generally designated  10 , is shown constructed according to the present invention. The structure having a fire resistance rated, area separation wall includes a first building unit  12  and a second building unit  14 . Additional building units  16  may also be part of the structure  10 . The first building unit  12  and second building units  14  may be occupiable spaces, which may be residentially occupiable spaces, such as town homes. A town house is generally defined by the 2000 International Residential Code as a single-family dwelling unit constructed as a group of three or more attached units in which each unit extends from foundation to roof with open space on at least two sides. A two-hour fire resistance rated, area separation wall  18 , constructed according to the present invention, is located between each building unit  12 ,  14 ,  16 .  
       FIG. 2  is a side view of one embodiment of the two-hour fire resistance rated, area separation wall  18  including an interior support structure  22  having only an outer membrane  24  on each side of the interior support structure  22 , and a substantially organic thermal insulation barrier  26  between the outer membranes  24 . The interior support structure  22  includes at least two structurally independent interior support members  28 . The structurally independent interior support members  28  include a plurality of vertical members such as conventional 2×4. The plurality of vertical members may be spaced apart no more than about 16 inches and include cross bracing  30  at about their mid height. The two-hour fire resistance rated, area separation wall  18  includes a physical gap  32  between the structurally independent interior support members  28 . A tying structure  34  connects the first unit  12  and the second unit  14 . The tying structure  34  may be a conventional 2×8. The tying structure is overlaid top plates  37  that is attached to the top edge of the interior support members  28 . A bottom plate  36  is attached to the bottom edge of the interior support members  28 . Also, the maximum height of the fire resistance rated area separation wall preferably is 10 feet, whereupon another wall would begin.  
      The outer membranes  24  preferably are a fire resistant wallboard, including Type X and Type C gypsum wallboard (GWB) as defined in ASTM C11. The gypsum wallboard preferably conforms to ASTM Test C-36-96. The substantially organic thermal insulation barrier  26  between the outer membranes  24  may be selected from the group consisting of fibrous material, granular material, pellet material, aggregated material, agglomerated material and mixtures thereof. The substantially organic thermal insulation barrier  26  may be a natural material. The natural material may be cellulosic. The substantially organic thermal insulation barrier  26  may be an acoustically non-conductive material.  
       FIG. 3  is a side view of the preferred embodiment of the two-hour fire resistance rated, area separation wall  18  that does not include a tying structure  34  connecting the first unit  12  and the second unit  14 . Instead, the two-hour fire resistance rated, area separation wall  18  described in  FIG. 3  includes a separate top plate  37  attached to another top plate  37  that is attached to the top edge of the interior support members  28 . In both embodiments, a bottom plate  36  is attached to the bottom edge of the interior support members  28 . Also, in both embodiments, the maximum height of the fire resistance rated area separation wall preferably is 10 feet, whereupon another wall would begin.  
      As can be seen, the top of the area separation wall can be formed either by a top plate  37  overlaid with a tying structure  34  or by a top plate  37  overlaid with a second top plate  37  separated by an inch. Thus, there are two configurations. One is with a single top plate  37  and a tying structure  34  that joins the two walls (shown in  FIG. 2 ) and the other is two separate top plates with a space between them (shown in  FIG. 3 ). In either case, this results in a double top plate being formed.  
      Certain modifications and improvements will occur to those skilled in the art upon reading of the foregoing description. It should be understood that all such modifications and improvements have been deleted herein for the sake of conciseness and readability but are properly within the scope of the following claims.