Patent Publication Number: US-11649628-B2

Title: Area separation firewall system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims benefit of U.S. Provisional Patent Application No. 63/262,268 filed Oct. 8, 2021, titled “AREA SEPARATION FIREWALL SYSTEM,” which is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure relates to area separation firewalls. More particularly, the disclosure relates to an improved firewall for use in area separation firewall systems, with this system including wider, thinner pieces of gypsum wallboard that are easier to manufacture and install as compared to traditional 1″ thick shaft liner wallboard. 
     BACKGROUND 
     International, state, regional and local building codes require that multi-family residential buildings include certain fire protection features, such as firewalls between residential units. The standard for qualifying fire rated systems is either ASTM E119 (“Standard Test Methods for Fire Tests of Building Construction and Materials”) or ANSI/UL 263 test (“the Standard for Safety of Fire Tests of Building Construction Materials”). During this testing, an area separation firewall system therein is heated to 1000° F. and then ramped to 2000° F. The firewall must be able to resist this heat for a specified period of time, such as two hours. Another aspect of this testing is a hose stream test, wherein a pressurized stream of water is directed at the vertical fire resistive wall assembly after fire endurance exposure simulating a fire being extinguished. The vertical firewall must be able to maintain its structural integrity, and not allow water to pass through it. 
     For decades, multi-family residential firewalls have been constructed with two pieces of 1″ thick shaft liner wallboard. These wallboard panels are particularly difficult to manufacture and typically slows production by a factor of two or more. These thick pieces of wallboard are also cumbersome and only 2′ wide—as compared with a 4′ width for other wallboard panels—in order to manage the weight thereof. This decreased width translates to added materials and labor when installing the firewall, since the 2 pieces of shaft liner wallboard must be joined with the next section using a metal H-Stud. Despite the long tenure of these firewalls, little improvement has been made to the conventional design. As such, there remains a great need for an improved firewall wallboard that can be efficiently manufactured and installed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments of the present disclosure will be understood more fully from the detailed description given below and from the accompanying drawings. In the drawings, like reference numbers may indicate identical or functionally similar elements. Embodiments are described in detail hereinafter with reference to the accompanying figures, in which: 
         FIG.  1    is a top view of a prior art area separation firewall. 
         FIG.  2    is a top view of an area separation firewall according to an embodiment of the present disclosure. 
         FIG.  3    is a side view of an area separation firewall according to an embodiment of the present disclosure. 
         FIG.  4    is a side view of an area separation firewall according to another embodiment of the present disclosure. 
         FIG.  5    is an opposite side view of the area separation firewall of  FIG.  3    or  FIG.  4   . 
         FIG.  6    is a cross-sectional side view of an area separation firewall within an intermediate floor intersection according to an embodiment of the present disclosure. 
         FIG.  7    is a cross-sectional side view of an area separation firewall at a roof junction according to an embodiment of the present disclosure. 
         FIG.  8    is a cross-sectional top view of an area separation firewall at an exterior wall intersection according to an embodiment of the present disclosure. 
         FIG.  9    is a graph showing the results of Example 1. 
         FIG.  10    is a graph showing the results of Example 2. 
     
    
    
     DETAILED DESCRIPTION 
     The following disclosure provides many different embodiments or examples. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. 
       FIG.  1    is a top view of a conventional 2-hour area separation firewall. The area separation firewall includes a pair of opposite interior walls  5  each supported on a series of studs  4 , which are typically made of wood. Between the interior walls  5  is a firewall  8  spaced from the studs  4  by an airgap  7 , which may be about ¾″. The firewall  8  includes two-wallboard-thick panels comprising two, 1″ thick wallboards  3 . Each wallboard  3  may have a width W 0  of about 2′. The panels of the firewall  8  are joined together by H-studs  2  and an end panel of the firewall  8  is capped with a C-stud  1 . The C-studs  1  and H-studs  2  may be made of metal, such as steel. The H-studs are fixed to wood framing via clips  6 , which are typically made from aluminum and configured to break away if the wood framing collapses in a fire thereby leaving the firewall  8  standing. 
       FIG.  2    is a top view of a 2-hour area separation firewall  100  according to an embodiment of the present disclosure. The area separation firewall  100  includes a pair of opposite interior walls  50  each supported on a series of studs (framing)  40 , which are typically made of wood or metal. The studs  40  are separated by a maximum distance W 2  of about 2′. Between the interior walls  50  is a firewall  80  spaced from the studs  40  by an airgap  70  of a minimum of ¾″. The firewall  80  includes four-wallboard-thick panels comprising four wallboards  30  each having a nominal thickness of, e.g., less than 1″ or about 0.5″. Accordingly, the firewall  80  may be about as thick as a traditional firewall having two 1″ thick pieces of wallboard. Each wallboard  30  may have a width W 1  of about 2′, greater than 2′, about 3′, about 3.5′, about 4′, greater than 4′, about 54″, or at most 54″. The increased width of the wallboards  30  is made possible due to the thinner profile, whereby the wallboards  30  may be about as heavy as traditional firewall wallboards. The panels of the firewall  80  are joined together by H-studs  20  and an end panel of the firewall  80  is capped with a C-stud  10 , such as a 2″ C-stud. The firewall  80  may be friction fit into each of the C-studs  10  and H-studs  20 . The H-studs  20  and/or C-studs  10  may be attached to the wood framing  40  with aluminum clips  60 . In some embodiments, the clips  60  are made from aluminum and designed to melt or break away if the wood framing  40  collapses in a fire thereby leaving the firewall  80  standing. 
     In any embodiment, the material used for the wallboard  30  is typically more fire resistant than that used for the interior walls  50 . In some embodiments, the wallboard  30  may be comprised of gypsum, fiber glass, and vermiculite. In one or more embodiments, the wallboard  30  comprises one or more of a dispersant, a fire retardant (retarder), a chelating agent, a soap, a binder or adhesive, an accelerator, a surfactant, an acid, a stabilizing agent, and/or a foaming agent. In some embodiments, the dispersant may include polynaphthalene sulfonate in a sodium or calcium salt solution (having 2-80% solids content). In some embodiments, the binder or adhesive may include starch, such as acid-modified corn starch (AMCS) or pre-gelatinized corn starch. In some embodiments, the retarder or chelating agent may include pentasodium diethylenetriaminepentaacetate. In some embodiments, the acid may include boric acid. In some embodiments, the stabilizing agent is sodium trimetaphosphate (STMP). In some embodiments, the soap, surfactant, and/or foaming agent may include ammonium alkyl ether sulfate. In one embodiments, the wallboard may have the following formulation: 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Component 
                 Content (lbs./msf) 
               
               
                   
                   
               
             
            
               
                   
                 Retarder 
                 0.02-4.0  
               
               
                   
                 Stucco 
                 1300-1700 
               
               
                   
                 Soap 
                 1.0-7.0 
               
               
                   
                 Starch 
                  3.0-12.0 
               
               
                   
                 Vermiculite 
                 25.0-65.0 
               
               
                   
                 Fiber glass 
                  3.0-16.0 
               
               
                   
                 Core adhesive 
                  6.0-25.0 
               
               
                   
                 Dispersing agent 
                 1.0-8.0 
               
               
                   
                 Foaming agent 
                 0.01-5.0  
               
               
                   
                 Boric acid 
                 0.02-5.0  
               
               
                   
                 STMP 
                 1.50-9.0  
               
               
                   
                 Accelerator 
                  6.0-15.0 
               
               
                   
                 Average Weight 
                 1950-2100 
               
               
                   
                   
               
            
           
         
       
     
     In one or more embodiments, the wallboard  30  may be a commercially available wallboard from American Gypsum sold under the tradename M-BLOC® Ekcel™ TYPE X. In one or more embodiments, the wallboard  30  does not include asbestos and/or does not include detectable levels of formaldehyde. Since the firewall  80  is usually installed prior to the completion of the roof and exterior walls, the wallboards  30  may be exposed to the elements for a period of time. As such, in some embodiments, an exterior surface of the wallboard  30  may be wrapped in a mold and moisture resistant covering. In some embodiments, the mold and moisture resistant covering may be one that has scored at least a 8, 9 or 10 under the ASTM D3273 (Standard Test Method for Resistance to Growth of Mold on the Surface of Interior Coatings in an Environmental Chamber). In some embodiments, coverings, such as the mold and moisture resistance covering discussed above, may cover the face and back of the wallboard  30 . In some embodiments, the coverings comprise a paper or a glass mat. 
     In some embodiments, the interior walls  50  may be formed from ½″ or ⅝″ thick gypsum board available from American Gypsum under the tradenames LIGHTROC® or CLASSICROC® or any other fire rated or non-fire rated wallboard panel. 
     Turning to  FIG.  3   , each four-wallboard-thick panel may be supported at the top and bottom thereof with a C-Runner channel  12 . The pieces of wallboard  30  each have a height H 4  that corresponds to the height of the H-stud  20  in use. In some embodiments, the height H 4  may be up to 8′, up to 10′, up to 12′, up to 14′ or up to 16′. As will be described in more detail below, the area separation firewall  100  will typically extend through all floors of the building and therefore will have a height that is generally equivalent to the height of the building. In order to provide additional support to the wallboards  30 , fasteners  94  may by installed to fasten the four layers of wallboard  30  to one another. In some embodiments, the fasteners  94  are nails, screws, or an adhesive. In some embodiments, the fasteners  94  are 1½″ Type G laminating screws. In some embodiments, the fasteners  94  are long enough to penetrate through one, two, or three layers of wallboard  30 . In some embodiments, the fasteners  94  are shorter than a thickness of the firewall  80  so that the fasteners  94  do not protrude out of the firewall  80 . In some embodiments, the fasteners  94  are greater than ½ the thickness of the firewall  80  such that fasteners  94  installed on opposite sides of the firewall  80  are capable of laminating the layers of wallboard  30  to each other. 
     When the fasteners  94  are employed, they may be configured in a random assortment or they may be configured in a pattern  90 . In the embodiment shown in  FIG.  3   , the fasteners  94  are equally spaced from each other within the pattern  90  and the pattern  90  is spaced from the edges of the wallboard  30 . In particular, within the pattern  90 , the fasteners  94  are spaced by a lateral distance D 2  and a vertical distance H 2 . The distances D 2  and H 2  may be the same or different. In some embodiments, the distance D 2  is less than the distance H 2 . In other embodiments, the distance D 2  is greater than the distance H 2 . The pattern  90  is spaced from the vertical edges of the wallboard  30  by distances D 1  and D 3 , which may be the same or different. In some embodiments, one or both of the distances D 1  and D 3  is the same as the distance D 2 . The pattern  90  is spaced from horizontal edges of the wallboard  30  by distances H 1  and H 3 , which may be the same or different. In some embodiments, the distances D 1 , D 2 , D 3 , H 1 , H 2 , and H 3  are each independently from about 3″ to about 36″, from about 6″ to about 24″, from about 12″ to about 30″, from about 20″ to about 36″, about 16″, about 24″, or about 12″. 
     With reference to  FIG.  4   , an alternative pattern  90 A is shown. In  FIG.  4   , the pattern  90 A is spaced from the edges of the wallboard  30  by distances D 4  and D 7 , which may be the same or different from one another. The pattern  90 A includes a middle column of fasteners  94  spaced from the outer columns of fasteners  94  by distances D 5  and D 6 , which may be the same or different from one another. In some embodiments, the distances D 4 , D 5 , D 6 , and D 7  are each independently from about 3″ to about 36″, from about 6″ to about 24″, from about 12″ to about 30″, from about 20″ to about 36″, about 16″, about 24″, or about 12″. 
     Turning to  FIG.  5   , an opposite side of the wallboard  30  panel may also include a set of fasteners  94 . In some embodiments, the fasteners  94  are arranged in a second pattern  92 , which may be the same or different from the pattern  90 . In  FIG.  5   , the pattern  92  is distinct from, but complementary to, the pattern  90 . Arranging the fasteners  94  in this manner provides excellent structural support while conserving materials. The fasteners  94  are spaced from one another within the pattern  92  by a lateral distance D 9  and a vertical distance H 2 . Although the embodiment shown includes the same vertical spacing for patterns  90  and  92 , the respective vertical spacings may be, for example, offset by a distance of about 3″, about 6″, about 9″, or about 12″. In some embodiments, the distance D 9  is greater than the distance D 2 . In other embodiments, the distance D 9  is less than the distance D 2 . In yet other embodiments, the distance D 9  is equal to the distance D 2 . The pattern  92  is spaced from the vertical edges of the wallboard  30  by distances D 8  and D 10 , which may be the same or different. In some embodiments, one or both of the distances D 8  and D 10  is the same as the distance D 9 . In some embodiments, the distances D 8 , D 9 , and D 10  are each independently from about 3″ to about 36″, from about 6″ to about 24″, from about 12″ to about 30″, from about 20″ to about 36″, about 16″, about 24″, or about 12″. In an embodiment, the distance D 1  is about 12″, the distance D 2  is about 24″, the distance D 3  is about 12″, the distance D 4  is about 12″, the distance D 5  is about 12″, the distance D 6  is about 12″, the distance D 7  is about 12″, the distance D 8  is about 16″, the distance D 9  is about 16″, the distance D 10  is about 16″, the distance H 1  is about 12″, the distance H 2  is about 24″, the distance H 3  is about 12″, and the distance H 4  is about 10′. 
     In any of the above embodiments, the fasteners  94  may be spaced such that any one fastener  94  has at least one adjacent fastener  94  within a set maximum distance. The at least one adjacent fastener  94  may be on the same side of the firewall  80  as the any one fastener  94  or may include fasteners  94  on the opposite side of the firewall  80 . In some embodiments, the set maximum distance is from about 6″ to about 24″, about 8″, about 12″, about 14″, about 16″, about 18″, about 20″, about 22″, or about 24″. 
     With reference to  FIG.  6   , in multi-level buildings, the area separation firewall  100  may need to traverse an intermediate floor junction. As shown, an airgap  70  is maintained along an entire length of the area separation firewall  100 . In some embodiments, an additional fire blocking material  32  may be required proximate the floor joists  46 . The fire blocking material  32  may comprise, for example, gypsum wallboard (such as that described for wallboard  30 ) or a mineral or glass fiber insulation. Insulation  48 , such as glass fiber batt, may be placed as needed between the interior walls  50 . Between levels  80   a  and  80   b  of the firewall  80 , two C-studs  10  may be positioned back-to-back. Although the junction (at C-studs  10 ) between levels  80   a  and  80   b  is shown at a position above the upper floor  52   a , the junction may be between the floor  52   a  and ceiling  52   b  or below the ceiling  52   b . In some embodiments, caulk or another sealant may be used at the junction between C-studs  10  to create a smoke-tight joint. 
     Next, turning to  FIG.  7   , the area separation firewall  100  is shown at a junction with a roof deck  56 . The roof deck  56  includes roofing  56   a . In some embodiments, a layer  54  is needed below the roof deck  56 , wherein the layer  54  may be, for example, a layer of wallboard such as that described above. In some embodiments, the layer  54  is about ⅝″ thick. A C-stud  10  may cap the firewall  80  where it meets the roof deck  56 . At this juncture, caulk or another sealant may be used to create a smoke-tight joint. In some embodiments, an additional fire blocking material  32  may be required proximate the framing  44  (including ceiling joists). The fire blocking material  32  may be as described above. 
     With reference to  FIG.  8   , the area separation firewall  100  is shown at a junction with an exterior wall  58 . In some embodiments, a sheathing layer  48  may be included inside of the exterior wall  58 . In some embodiments, the sheathing layer  48  is about ⅝″ thick. A C-stud  10  may cap the firewall  80  where it meets the sheathing layer  48  or the exterior wall  58 . At this juncture, caulk or another sealant  12  may be used to create a smoke-tight joint. 
     Although the firewall  80  is described herein as comprising four pieces of wallboard  30 , the firewall may include, for example, three, five, or six pieces of wallboard  30 . In any embodiment, the thickness of the firewall  80  may be maintained at, for example, approximately 2″ by appropriately adjusting the thickness of the wallboard  30 . For example, three pieces of wallboard  30  may each have a thickness of about ⅔″. 
     According to embodiments of the present disclosure, the firewall  80  may provide similar or improved fire protection as compared with conventional firewalls while significantly decreasing the cost of production and installation. As discussed above, conventional 1″ thick, 2′ wide wallboard can slow production by a factor of two or more. Conversely, the wallboard  30  disclosed herein does not cause such reduction of production. Additionally, even though four pieces of wallboard  30  are used for each panel (as compared to two in conventional firewalls) and fasteners  94  may be required, installation of the firewall  80  of the present disclosure is still faster than that of conventional firewalls. This is primarily because the wider pieces of wallboard  30  result in fewer H-studs  20  being required. 
     EXAMPLES 
     Example 1 
     An area separation firewall generally as shown in  FIG.  2    was assembled using four pieces of ½″ thick wallboard for the firewall, type G laminating screws as fasteners for the wallboard, steel H-studs, steel C-studs, wood studs spaced at 16″, glass fiber insulation batts friction fitted into cavities between the wood studs, and regular ½″ thick gypsum wallboard secured to the wood studs for the interior walls. This assembly was then tested according to standard ASTM E90-09 (2016): Laboratory Measurement of Airborne Sound Transmission of Building Partitions and Elements. The results of this test are shown in  FIG.  9   , wherein the Sound Transmission Class (STC) contour is shown as a double line, the transmission loss (TL) is shown as a single line, and the STC deficiencies are shown as a bar graph. This test resulted in an STC rating of 56, which corresponds to the STC contour shown. 
     Example 2 
     An area separation wall was assembled as described in Example 1, except that the wood studs were spaced at 24″ o/c. This assembly was then tested according to standard ASTM E90-09 (2016). The results of this test are shown in  FIG.  10   . This test resulted in an STC rating of 61, which corresponds to the STC contour shown. 
     Example 3 
     An area separation wall was assembled as described in Example 2. This assembly was then tested according to standard, Fire Tests of Building Construction and Materials, UL 263 (ASTM E119), 14 th  Edition dated Aug. 5, 2021 and the Standard, Standard Methods of Fire Endurance Tests of Building Construction and Materials CAN/ULC-S101-14, Fifth Edition, dated Dec. 2, 2020. The observations during the fire test are summarized in Table 2 below. 
     
       
         
           
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                   
                 Exposed  
                   
               
               
                   
                 (E) or 
                   
               
               
                   
                 Un- 
                   
               
               
                 Test 
                 exposed 
                   
               
               
                 Time, 
                 (U)  
                   
               
               
                 Min 
                 Surface 
                 Observations 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 0 
                 U 
                 The measured velocity across the unexposed surface  
               
               
                   
                   
                 of the test assembly was 0 feet per second. 
               
               
                 0 
                 E&amp;U 
                 Gas on. 
               
               
                 5 
                 E 
                 Entire exposed face has turned black. 
               
               
                 10 
                 E 
                 Exposed side board has turned gray/white. Paper is  
               
               
                   
                   
                 burning away, core visible in various spots. 
               
               
                 17 
                 E 
                 Exposed side board joints have started to open (less  
               
               
                   
                   
                 than½ in.). Upper most panel exhibiting cracks. 
               
               
                 22 
                 E 
                 Upper most board joint has opened to about 1 in.,  
               
               
                   
                   
                 wood studs are visible and flaming. Top and bottom  
               
               
                   
                   
                 boards showing cracks. 
               
               
                 26 
                 E 
                 Stud pattern visible through boards. 
               
               
                 28 
                 E 
                 Bottom board joint has opened to about 1 in. Crack in 
               
               
                   
                   
                 center of bottom board has grown. 
               
               
                 33 
                 E 
                 Significant flaming at exposed board joints. No  
               
               
                   
                   
                 exposed side board fall off at this point. 
               
               
                 40 
                 E 
                 Middle board engulfed in flame. Top board joint  
               
               
                   
                   
                 opened to more than 1 in. Top board showing 
               
               
                   
                   
                 significant waving. No board fall off at this time. 
               
               
                 46 
                 E 
                 Middle exposed panel has fallen. Top and bottom still 
               
               
                   
                   
                 attached. 
               
               
                 48 
                 E 
                 Middle north side of exposed panel had fallen. 
               
               
                 51 
                 E 
                 Top exposed board still attached. Studs visible at  
               
               
                   
                   
                 center area and still intact. 
               
               
                 54 
                 E 
                 Exposed side wood studs have fallen. ½ in.  
               
               
                   
                   
                 Wallboard paper is charring 
               
               
                 60 
                 E 
                 Paper on wallboard had turned fully white. 
               
               
                 65 
                 E 
                 H-studs showing rippling. 
               
               
                 70 
                 E 
                 Wallboard showing rippling in center of assembly. 
               
               
                 95 
                 E 
                 Majority of top panel of unclassified board (interior 
               
               
                   
                   
                 wallboard) has fallen. 
               
               
                 130 
                 E 
                 Wallboard layers start to deflect further and pull away. 
               
               
                 135 
                 E 
                 Second layer of wallboard, north side has fallen. First  
               
               
                   
                   
                 laye rof wallboard south side has fallen. 
               
               
                 145 
                 E 
                 Down to third layer of wallboard both north and  
               
               
                   
                   
                 south side. 
               
               
                 159 
                 E&amp;U 
                 Gas off, assembly no longer maintained load. All  
               
               
                   
                   
                 framing and gypsum board except for the outer  
               
               
                   
                   
                 most unclassified layer and wood studs had 
               
               
                   
                   
                 fallen into the furnace. 
               
               
                   
               
            
           
         
       
     
     As shown above, the assembly met the requirements for a 2-1/2 hour (150 minutes) load bearing wall. The finish rating is defined as the time necessary to raise the average temperature measured on the face of the wood studs nearest the fire by 250° F. or the time required to raise the temperature on the wood studs by 325° F. at any point. The average temperature measured on the wood studs was 65° F. before the test. Therefore, the average limiting temperature was 315° F. and the individual limiting temperature was 390° F. 
     The limiting temperatures for the unexposed surfaces did not occur during the 159 min. test duration. The average limiting average temperature and individual limiting temperatures were 162° F. and 180° F., respectively, at 159 min. 
     No suspected hot spots developed during the test requiring the application of cotton waste or the roving thermocouple. 
     Next, a duplicate assembly was heated according to the above standards for 1 hour prior to a hose stream test. The observations during the heating are summarized in Table 3 below. 
     
       
         
           
               
               
               
             
               
                 TABLE 3 
               
               
                   
               
               
                   
                 Exposed  
                   
               
               
                 Test  
                 (E) or 
                   
               
               
                 Time, 
                 Unexposed 
                   
               
               
                 Hr:Min 
                 (U) Surface 
                 Observations 
               
               
                   
               
             
            
               
                 0:00 
                 E/U 
                 The measured velocity across the unexposed  
               
               
                   
                   
                 surface of the test assembly was 0 FPS. 
               
               
                 1:00 
                 E/U 
                 No significant changes occurred. Gas off. 
               
               
                   
               
            
           
         
       
     
     The assembly was then subjected to the impact, cooling, and eroding action of a 30 psi water stream applied through a 1-1/8 in. diameter nozzle at a distance of 20 ft. for 2-1/2 min. During the hose stream test, no water penetrated through the 4 layers of ½″ gypsum. boards that created the area separation wall. Also, no water penetrated beyond the unexposed surface during the 2-1/2 minute hose stream test. Instead, the assembly remained intact during the 2-1/2 minute hose stream test. 
     Although various embodiments have been shown and described, the disclosure is not limited to such embodiments and will be understood to include all modifications and variations as would be apparent to one of ordinary skill in the art. Therefore, it should be understood that the disclosure is not intended to be limited to the particular forms disclosed; rather, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure as defined by the appended claims.