Patent Publication Number: US-2009223159-A1

Title: Firestop block and thermal barrier system for fluted metal decks

Description:
FIELD OF THE INVENTION 
     The present invention relates to firestop blocks and a thermal barrier system for building structures, and more particularly to thermal barriers for “head-of-wall” joint assemblies between tops of walls and ceilings or floors. 
     BACKGROUND OF THE INVENTION 
     Firestops are thermal barrier materials or combinations of materials used for filling gaps and openings such as in the joints between fire-rated walls and/or floors of buildings. For example, firestops can be used in walls or floors to prevent fire and smoke from passing through the gaps or openings required for cables, pipes, ducts, or other conduits. Firestops are also used to fill joint gaps that occur between walls, between a ceiling and the top of a wall (“head-of-wall” joints), and between a floor and vertical wall (“perimeter” joints). 
     So-called “head-of-wall” joints pose a number of challenges for the firestopping industry. Walls are generally made of concrete block or other type of fire resistant block. Ceilings (or floors) are increasingly being made by pouring concrete onto fluted steel. Walls are also increasingly being made of gypsum wallboard affixed to a framework of metal studs capped by a horizontally extending track. Although the distance between the concrete block wall or horizontally extending track at the top of the wall is often fixed in relationship to the ceiling, the concrete block and gypsum wallboards are subject to expansion and contraction due to motion of other building components, ground settling, or other causes. 
     For such head-of-wall joints, it is known to use mineral wool batt as a thermal resistant firestop material due to its ability to provide for cyclic movements in the wallboard material. Mineral wool batt is also used at the head-of-wall joints for block walls. See, e.g., U.S. Pat. No. 4,756,945. The mineral wool is cut into separate sheets that are appropriately sized depending on the specific geometry of the fluted steel ceiling. The sheets need to be stacked and compressed (e.g., a minimum 50%) when packed into the joint gap. In some situations, a fireproofing material is spray-applied into the spaces of the fluted ceiling to supplement the mineral wool in the joint. In either case, the mineral wool approach requires labor and time. 
     After packing of the mineral wool batt into place above the wall, the construction worker must then spray an elastomeric coating, using a minimum one-eighth inch thickness, against the exposed side surfaces of the compressed mineral wool layers. The coating must overlap a minimum of one half inch onto the ceiling and wall surfaces. Thus, the use of mineral wool batt and elastomeric spray coating provides for the ability of the resultant firestop to accommodate some cyclic movement (compression and extension) in various components such as the gypsum wallboards on either side of the head-of-wall joint. 
     In addition, a thermal barrier and method is known that employs introducing into the opening or gap at least one (empty) thermal barrier molding bag to receive a flowable firestop material that is to expand the bag within the hole or joint gap and harden within the bag; thereby molding a thermal barrier within the hole or joint gap. See U.S. Pat. No. 7,043,880. This method is inconvenient, labor intensive and time-consuming, and therefore quite costly. 
     One objective of the present invention is to provide a more convenient and cost-effective method for installing a thermal barrier in shaped openings and joint gaps such as are found in “head-of-wall” joints. 
     Another objective of the invention is to provide novel thermal barriers that may be used conveniently and safely in hard-to-reach building or ship vessel joint gaps or holes. For example, the location of a head-of-wall joint next to an elevator shaft or crawl space would render difficult the installation of mineral wool/coating systems, because the task of coating both sides would be complicated by the lack of convenient access. With the present invention, a thermal barrier for both sides could be completed while the wall is being built, thereby obviating this problem. 
     A still further objective of the invention is to enhance safety of installation. An applicator must climb up and down ladders on a frequent basis when working on head-of-wall joint assemblies. In the first instance, there is the fitting and hand-packing of mineral wool material into the joint gap. In the second instance, there is the coating of elastomeric material to create a continuous surface between the ceiling, firestop, and wall. In both cases, the ladder may require frequent repositioning, and this is especially the case where joint gaps extend lengthy distances of ten to twenty feet or more. Frequent climbing up and down ladders would also be required in “perimeter barrier” systems if it were desired to apply an elastomeric coating onto the bottom face of a mineral wool firestop that has been packed between a floor and a wall, because the installer would need to go to the floor below the firestop to coat the bottom face of the mineral wool material. With the present invention, it is not necessary to repeatedly access the work area. 
     In view of the prior art disadvantages, novel thermal barriers and methods are believed to be needed. 
     SUMMARY OF THE INVENTION 
     In surmounting the disadvantages of the prior art, the present invention provides a method and system for installing a thermal barrier in openings and gaps in or between building structures such as walls, ceilings and floors. In so doing, the present invention provides increased convenience, effectiveness and safety in comparison to the prior art mineral wool/coating and other methods. The thermal barriers of the present invention have the ability to conform to the openings and gap spaces between the tops of walls and fluted metal decks. The thermal barriers also have the ability to permit movement of the various building structures around the openings or gaps. In particular, protection on both sides of “head-of-wall” joint assemblies (arising between a wall and ceiling), may be conveniently accomplished by the thermal barriers and methods of the present invention. 
     An exemplary method of the present invention comprises providing a first and second structure which define therebetween a gap, such as the joint gap between a wall and a fluted ceiling, introducing into the opening or gap at least one firestop block that is constructed of firestop material and configured to be slideably inserted into the fluted opening between the wall and the floor. A flexible firestop material, such as an elastomeric sealant, silicone, polyethylene or polyurethane foam backer rod, or spray, as are commercially available, is supplied as a sealant of filler between any remaining space between the firestop block and the wall or fluted metal ceiling, thereby forming a molded a thermal barrier within the fluted hole or gap. 
     The firestop blocks of the invention can be made of any dense, firestop material as recognized in the UL Fire Resistance Directory, 2007 ed., which is incorporated herein by reference, but cementitious materials such as concrete blocks (CAZT) or pre-cast concrete units (CFTV) are preferred. In addition, the firestop blocks may be made of fire resistant intumescent materials, which expand when they are heated, as by a fire. Intumescent materials, however, may be more expensive than cementitous materials. Although the firestop blocks can be of any shape to match the shape of the fluted metal deck, they are generally configured as trapezoidal shaped bars and are dimensioned to be slidably inserted into the openings created at the tops of walls and the fluted metal deck setting on top of the wall. The base and height of the firestop blocks may be of any dimension as required by the shape of the flutes on the metal deck, but are generally about 4-6 inches wide, with about 5 inches being preferred, are generally 1-4 inches high, with 2½ inches being preferred. The firestop blocks may also be of any length, but generally, 16 to 18 inches is preferred. 
     Typically, both the floor and fluted metal ceiling of the structure are in place when the walls are constructed. The walls are thus built up to the fluted metal ceiling, leaving a space at the top, particularly with respect to the position of the flutes. The firestop blocks are then set on the tops of the walls and, in the case of cement block walls, are held in place by mortar on the underside of the firestop blocks. Where the wall is made of gypsum and is capped by a metal track, fire resistant adhesive can be used to attach the firestop block to the metal track. The spaces that remain on the top and sides of the firestop block and the fluted metal deck can be filled or sealed using intumescent fillers, caulks or sealers as are available commercially, e.g., such as hydratable cementitious slurry, an intumescent material, a superabsorbent polymer; silicone; polyurethane (foam); hydrated silica gel; inorganic dessicants (e.g., molecular sieves such as zeolites; silica gel; calcium oxide; calcium sulfate; calcium chloride; barium oxide; phosphorous pentoxide); fibers; mineral wool; fiber glass; or mixture thereof. 
     Firestop barriers made in accordance with the above-described in-situ methods of the present invention provide excellent fire resistance and sealing ability as well as smoke and acoustic barrier properties that also provides for flexibility. They are also sufficiently strong to resist dislodgement from the gap or opening due to pressure (e.g., force from a water hose) and are highly amenable to visual inspection. 
     Further features and advantages of the invention are described in detail hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following detailed description of exemplary embodiments may be more readily appreciated in conjunction with appended drawings, wherein: 
         FIG. 1  is a perspective view of a so-called “head-of-wall” joint assembly for a gypsum wall (PRIOR ART); 
         FIG. 2  is a perspective view of a so-called “head-of-wall” joint assembly for a block wall (PRIOR ART); 
         FIG. 3  is a perspective diagram of a mineral wool batt firestop “head-of-wall” joint assembly (PRIOR ART); 
         FIG. 4  is a perspective view of a firestop block for a fluted metal deck; 
         FIG. 5  is an elevation sectioned view of a firestop block for a fluted deck in use on a concrete masonry (“CMU”) wall illustrating deck flutes perpendicular to the CMU wall; and 
         FIG. 6  is an elevation sectioned view of a firestop block for a fluted deck in use on a CMU wall illustrating deck flutes parallel to the CMU wall. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings wherein the showings are for purposes of illustrating different embodiments of the present invention and not for purposes of limiting the same,  FIG. 4  perspectively illustrates a firestop block  10  configured to be slidably inserted into a fluted opening  42  (see  FIG. 1 ) of a fluted metal deck  40 . 
     The present invention employs one or more thermal barrier firestop blocks  10  that may be conveniently placed in openings in a structure, such as a wall, ceiling, or floor, or conveniently placed in gaps such as are defined in the joints between walls, ceilings, and/or floors. The firestop blocks are placed in the hole or joint gap formed between the head of a wall and a fluted metal deck. A flexible firestop material is introduced around the firestop block, thereby filling and sealing the space within the hole or joint gap and the fluted deck, and the filler/sealant firestop material is then allowed to harden within the hole or joint gap to provide a strong thermal barrier. 
     As shown in  FIG. 1 , a “head-of-wall” joint gap fluted opening  42  appears between the top of a vertical wall  44  and fluted metal ceiling or deck  40  (PRIOR ART). In this case, the wall is made by attaching a horizontal metal track  46  or runner to a fluted metal ceiling  40  which runs in a perpendicular manner to the wall  44 . The fluted metal ceiling  40  has fluted portions  40 B which are somewhat lower than the top ceiling portion  40 A, and thus a fluted opening  42  is defined between the top ceiling portion  40 B and the top of the wall, which in this case is the horizontal track  46 . Metal studs  48  are attached to the horizontal track  46  and connected to the floor below. Gypsum wallboards can be affixed on either side of the studs  48  to complete the wall assembly (PRIOR ART), and gaps  49  are typically left between the tops of the horizontal track  46  to permit movement of the wallboards. Typically, the fluted joint gap openings  42  can be about 5 inches wide at its narrowest point and about 6 inches wide at its widest point, although these dimensions may vary. Also, the height of the fluted joint gap openings  42  can vary, but generally is about three inches. 
     Similarly,  FIG. 2  illustrates a “head-of-wall” joint for a concrete block wall where gap fluted joint gap openings  42  appear between the top of the concrete block wall  45  and fluted metal ceiling or deck  40  (PRIOR ART). The fluted metal ceiling  40  has fluted portions  40 B which are somewhat lower than the top ceiling portion  40 A, and thus a fluted joint gap opening  42  is defined between the top ceiling portion  40 B and the top of the wall. Metal studs  48  are attached to the horizontal track  46  and connected to the floor below. Gaps  49  are typically left between the tops of the concrete block wall  45  and the fluted metal deck  40 . As illustrated, the fluted joint gap openings  42  can be about 6 inches wide and the height of the fluted joint gap openings  42  is about 3 inches. 
       FIG. 3  illustrates the prior art mineral wool batt system used to fill the fluted joint gap opening  42  and gaps  49 . There, the mineral wool batt is folded into the desired thickness and inserted into the corresponding openings. 
     As shown if  FIG. 4 , an exemplary firestop block  10  of the invention. The firestop blocks of the invention are made of any dense, firestop (or fire resistant) material as recognized in the UL Fire Resistance Directory, 2007 ed., which is incorporated herein by reference. Cementitious materials such as concrete blocks (CAZT) or pre-cast concrete units (CFTV) are preferred. Hydratable cementitious materials are also preferred. In addition, the firestop blocks may be made of fire resistant intumescent materials, which expand when they are heated, as by a fire. 
     The firestop blocks  10  of the invention are configured to conform to fluted joint gap openings  42 . Specifically, firestop block  10  is shaped as an elongated trapezoid, having a width dimension  12 , a height dimension  14  and a length dimension  16 . These dimensions are designed to generally conform to the corresponding dimensions of fluted joint gap openings  42 , but are sufficient to allow a space between the firestop block  10  and the fluted metal deck  40 . The base and height of the firestop block  10  may be of any dimension as required by the shape of the flutes  40 A and  40 B on the metal deck  40 , but generally, the width  12  of firestop block  10  is about 4-6 inches, with about 5 inches being preferred. The height  14  of the firestop blocks  10  are generally about 1-4 inches, with 2½ inches being preferred. The firestop blocks  10  may also be of any length  16 , but generally, about 16 or 18 inches is preferred. In addition, the firestop blocks  10  of the invention may contain scoring  18  on the upper surface  17  of the block  10 , so that the length  16  of the blocks  10  can be easily shortened by breaking the blocks at the scoring points in, in a manner known by masons. The scorings  18  can be located in any desired position on the upper surface  17  of the blocks, but are preferred to be in the center and in “quarter” positions so that the blocks  10  can be broken into 12 inch, 8 inch and 4 inch blocks to match the width of a CMU wall. 
     As shown in  FIG. 5 , an exemplary thermal barrier  1  of the invention is made by inserting at least one firestop block  10  at the top of a CMU wall  30  between the top of the wall  32  and top ceiling portion  40 A of the fluted metal ceiling  40 . As seen in  FIG. 5 , the direction of the wall  30  is perpendicular to the direction of the fluted joint gap openings  42  of the fluted metal ceiling  40 . In this embodiment, the firestop blocks  10  can be inserted lengthwise into the fluted joint gap openings  42 , after the length  16  is adjusted to the width of the wall  30 , if necessary. The fluted metal ceiling  40  is connected to the top  32  of wall  30  by applying a mortar material  50  to the top of the wall  30 . Thus, the fluted metal ceiling  40  is on the top of mortar  50  on top of wall  30 . When the firestop blocks  10  are inserted into the fluted joint gap openings  42 , the firestop blocks rest on top of the mortar  50  and are held in place when the mortar  50  hardens. 
     A flexible sealant or filler material  20  is then introduced into the remaining gap  22  in the fluted joint gap opening  42  between the firestop block  10  and the fluted ceiling  40 , which is generally about ½ of an inch. Both the mortar  50  and the sealant material  20  protect the exposed fluted joint gap opening  42 , so that heat and smoke do not penetrate through the wall at the top portion. 
     The sealant material  20  can be made of any flexible spacer material, such as intumescent fillers, caulks or sealers as are available commercially, e.g., such as hydratable cementitious slurry, an intumescent material, a superabsorbent polymer; silicone; polyurethane (foam); hydrated silica gel; inorganic dessicants (e.g., molecular sieves such as zeolites; silica gel; calcium oxide; calcium sulfate; calcium chloride; barium oxide; phosphorous pentoxide); fibers; mineral wool; fiber glass; or mixture thereof. 
     As shown in  FIG. 6 , another exemplary thermal barrier  1  of the invention can be made when the fluted metal ceiling  40  is oriented in the same direction as, or parallel to, the CMU wall  30 . In this case, the firestop blocks  10  are positioned on top of the wall  30  parallel to the direction of the wall. Enough firestop blocks  10  are inserted to fill the entire length of the fluted joint gap opening  42 . Thus, no fluted joint gap opening  42  appears on top of the wall in this case (because the spaces defined between ceiling surfaces  40 A and  40 B do not appear on either side of the wall). However, firestop sealant material  20  is introduced along the edges, such that a thermal firestop barrier is formed at the top of the wall  30 . 
     Thus, an exemplary method of the invention comprises inserting at least one firestop block  10  into the fluted joint gap opening  42  between two structures, such as a wall and ceiling, affixing the firestop blocks  10  on its bottom surface using a mortar material, then introducing a firestop sealant material into the spaces  22  ( FIG. 5 ) between the top and sides of the firestop block  10  and the fluted ceiling  40 , allowing the mortar and sealant material to harden inside the fluted joint gap openings  42 , whereby a thermal barrier is formed. 
     The thermal barriers of the invention are contemplated primarily for use in joint assemblies (e.g., floor-to-floor joint systems, wall-to-wall joint systems, floor-to-wall joint systems, and head-of-wall joint systems). 
     The term “hydratable cementitious” material as used herein refers to material that comprises at least one cementitious binder that begins to harden when mixed with water. Such a binder may be Portland cement, masonry cement, or mortar cement, gypsum, stucco, Plaster of Paris, aluminous cement, pozzolanic cement, magnesium oxychloride, magnesium oxysulfate, calcium silicate-hemihydrate, as well as materials such as limestone, hydrated lime, fly ash, blast furnace slag, and silica fume. The hydratable cementitious materials may in addition optionally include fine aggregates (e.g., sand), coarse aggregates (e.g., crushed stone, gravel, carbon flakes), or other fillers. Further exemplary cementitious materials may optionally contain, in addition to the cementitious binder, an intumescent material as will be further described hereinafter. 
     Exemplary hydratable cementitious materials used as flexible firestop materials in the present invention may further include one or more admixtures or additives, such as set accelerators, set retarders, water reducers (including superplasticizers and fluidity enhancing agents), rheology modifiers, air entraining agents, pigments or colorants, porous aggregates (e.g., shredded expanded polystyrene, expanded vermiculite, perlite, etc.), fibers, rheopectic agents (e.g., granular attapulgite, sepiolite, or mixtures thereof), surfactants, and other admixtures as conventionally known in the art. 
     Numerous patents and publications have disclosed intumescent compositions containing one or more polymeric materials in combination with phosphate-containing materials and carbonific or carbon-yielding materials, and such compositions, as known in the art, are believed to be suitable for use as firestop materials of the present invention. See, e.g., U.S. Pat. No. 3,513,114 of Hahn et al.; U.S. Pat. No. 5,487,946 of McGinniss et al.; U.S. Pat. No. 5,591,791 of Deogon; U.S. Pat. No. 5,723,515 of Gottfried; World Patent No. WO 94/17142 (PCT/US94/00643) of Buckingham; and World Patent No. WO 98/04639 (PCT/US96/12568) of Janci, all of which are incorporated fully herein by reference. 
     Other exemplary intumescent materials include graphite flakes impregnated with sulfuric or nitric acids. Inorganic material flakes capable of exfoliation when heated include vermiculite and perlite. 
     When installed in the joint gap of a building structure, the in-situ thermal barriers of the invention are tightly conformed to the shape of the structure or structures surrounding/defining the joint gap. It is envisioned that preferred thermal barriers of the invention, when installed in joint assemblies, are capable of passing fire endurance tests and hose stream tests in accordance with the “UL Standard for Safety for Tests for Fire Resistance of Building Joint Systems, UL 2079,” Third Edition, Dated Jul. 31, 1988, (Underwriters Laboratories, Inc., Northbrook, Ill.), incorporated fully herein by reference. 
     The foregoing discussion and examples are provided for illustrative purposes and not intended to limit the scope of the invention as claimed.