Head-of-wall fireblock systems and related wall assemblies

Abstract

A fire retardant head-of-wall assembly configured to seal a linear head-of-wall construction joint or gap when exposed to a heat source such as a building fire is disclosed. The inventive fire retardant head-of-wall assembly comprises a header track having an elongated intumescent strip affixed lengthwise on at least one of the outer sidewall surfaces of the header track and above a centrally located and outwardly protruding lengthwise corrugated groove. The intumescent strip comprises expandable graphite and a fire retardant (C 2 -C 8 alkyl diamine phosphate). When exposed to a heat source such as a building fire, the intumescent strip expands so to fill the head-of-wall construction joint or gap, thereby retarding or preventing the spread of smoke and fire. The inventive fire retardant head-of-wall assembly has been certified as complaint with respect to Underwriters Laboratories, Inc.'s standards set forth in its Tests for Fire Resistance of Building Joint Systems—UL 2079.

1 . A fire retardant head-of-wall assembly, comprising:
 an elongated sheet-metal footer track;   an elongated sheet-metal header track confronting and vertically spaced apart from the footer track, the header track including a web integrally connected to a pair of spaced apart and downwardly extending sidewalls, each sidewall having an upper sidewall portion adjacent to the web and a lower sidewall portion separated from the upper sidewall portion by an outwardly facing protrusion that runs lengthwise along each sidewall;   an elongated intumescent strip affixed lengthwise on at least one of the outer sidewall surfaces of the pair of sidewalls and above the outwardly facing protrusion;   a plurality of sheet-metal studs having upper and lower end portions, the studs being vertically positioned between the spaced apart and confronting footer and header tracks such that the lower end portions are received into the footer track and the upper end portions are received into the header track;   wallboard attached to at least one side of the plurality of studs, the wallboard having an elongated upper interior wallboard surface in contact with or proximate to the outer strip surface of the elongated intumescent strip.   
     
     
         2 . The fire retardant head-of-wall assembly of  claim 1  wherein the elongated intumescent strip comprises expandable graphite and a fire retardant. 
     
     
         3 . The fire retardant head-of-wall assembly of  claim 2  wherein the fire retardant is a C 2 -C 8  alkyl diamine phosphate. 
     
     
         4 . The fire retardant head-of-wall assembly of  claim 2 , further comprising a plurality of fasteners securing the upper end portions of the plurality of studs to the header track, each fastener extending through one of the pair of sidewalls of the header track and the upper end portion of one of the plurality of studs. 
     
     
         5 . The fire retardant head-of-wall assembly of  claim 4  wherein the elongated sheet-metal header track includes a plurality of vertically aligned slots positioned along at least one of the pair of downwardly extending sidewalls, with each fastener extending through one of the plurality of slots. 
     
     
         6 . The fire retardant head-of-wall assembly of  claim 5  wherein the fasteners are positioned about in the middle of its respective vertically aligned slot. 
     
     
         7 . The fire retardant head-of-wall assembly of  claim 6  wherein the intumescent strip partially covers each of the plurality of vertically aligned slots. 
     
     
         8 . The fire retardant head-of-wall assembly of  claim 7  wherein a top linear end surface of the wallboard is positioned perpendicular and about midway along the width of the intumescent strip. 
     
     
         9 . The fire retardant head-of-wall assembly of  claim 2 , further comprising an adhesive interposed between the intumescent strip and the at least one of the outer sidewall surfaces of the pair of sidewalls. 
     
     
         10 . The fire retardant head-of-wall assembly of  claim 2  wherein the intumescent strip has an outer protective polymeric coating. 
     
     
         11 . The fire retardant head-of-wall assembly of  claim 2  wherein the elongated sheet-metal header track has a generally U-shaped cross-section. 
     
     
         12 . The fire retardant head-of-wall assembly of  claim 2  wherein each of the plurality of sheet-metal studs has a C-shaped cross-section. 
     
     
         13 . The fire retardant head-of-wall assembly of  claim 1 , further comprising a compressible material sheet positioned between the web and the ceiling. 
     
     
         14 . An elongated U-shaped sheet-metal track, comprising:
 an elongated web integrally connected to a pair of spaced apart and outwardly extending sidewalls with the web and sidewalls defining a U-shaped profile, each sidewall having inner and outer sidewall surfaces, each sidewall having a first sidewall portion adjacent to the web and a second sidewall portion separated from the first sidewall portion by an outwardly facing protrusion that runs lengthwise along the sidewall, each sidewall having a plurality of slots positioned perpendicular to the lengthwise direction of the elongated web; and   an elongated heat expandable intumescent strip affixed lengthwise on at least one of the outer sidewall surfaces of the pair of sidewalls, the intumescent strip being positioned on the first sidewall portion and not on the second sidewall portion.   
     
     
         15 . The elongated U-shaped sheet-metal track of  claim 14  wherein each of the plurality of slots is positioned on the first and second sidewall portions. 
     
     
         16 . The elongated U-shaped sheet-metal track of  claim 15  wherein the intumescent strip partially covers each of the plurality of slots. 
     
     
         17 . The elongated U-shaped sheet-metal track of  claim 16 , further comprising a fire retardant adhesive interposed between the intumescent strip and the at least one of the outer sidewall surfaces of the pair of sidewalls. 
     
     
         18 . The elongated U-shaped sheet-metal track of  claim 17  wherein the intumescent strip further comprises an outer polymeric coating.