DESCRIPTION OF A PREFERRED EMBODIMENT

[0037] Referring to FIGS. 1, 2 and 3 of the drawings, the numeral 10 generally designates a steel roof deck comprising a plurality of sheets 12 of corrugated material, optional sheets 14 of foamed insulation material and sheets 16 of rigid mineral board, the sheets of mineral board 16 being secured by screws 18 to ridges 11 of the corrugated sheets, as will be hereinafter more fully explained. Valleys 13 of the corrugated sheet are secured to span across space between purlins 20, which in the illustrated embodiment are formed by open web steel joists. Valleys 13 are preferably secured to purlins 20 by powder actuated drive pins 21, self-drilling screws or by welding.

[0038] Corrugated sheet 12 preferably has flat ridge portions 11 and flat valley portions 13 of substantially equal length joined by connector portions 15 providing straight, parallel, regular and equally curved ridges and hollows. As best illustrated in FIG. 2, this configuration has a substantially equal distribution of surface area of the corrugated sheet above and below a neutral axis 19.

[0039] The sheet 14 of insulation material preferably comprises a closed cell foamed material such as polystyrene or polyisocyanurate formulated to provide a high degree of thermal insulating quality at ambient atmospheric temperatures. This component is optional and is used when a high degree of thermal insulation is desired.

[0040] Sheet 16 of mineral board preferably comprises a flat smooth sheet of incombustible, water resistant, fiberglass reinforced material having an impervious paper cover to permit migration of moisture from the mineral board when hot asphalt is applied thereto.

[0041] Screws 18 extend through sheets 14 of thermal insulation and sheets 16 of mineral board and are anchored in upper ridges 1 1 of corrugated sheet 12. It will be appreciated that screws 18 secure sheets 14 and 16 relative to upper ridges 11 of the corrugated sheet but do not extend into purlins 20. Thus, screws 18 contribute to the shear strength and shear stiffness of roof deck 10, but are not employed for securing the roof deck to the purlins.

[0042] It should be noted that screws 18 have enlarged heads 17 which engage the rigid sheet 16. As hereinbefore noted, sheet 14 of thermal insulation material has very low density and consequently has insufficient internal strength to hold screw heads 17 without pulling through the material.

[0043] The roof deck assembly 10 provides a flat surface having sufficient strength to support a waterproof roofing membrane and permits use of a symmetrical rib pattern in the corrugated sheet 12 which provides both flexural and diaphragm shear strength and shear stiffness when the upper ridges 11 are restrained against movement in a horizontal direction by the flat sheet 16 and screws 18.

[0044] Ridges 11 are in compression when a downwardly directed force is applied to the upper surface on the roof deck. Ridges 11 on the thin corrugated sheet 12 are somewhat analogous to a slender column when in compression. Screws 18 are positioned such that the unsupported length of the thin ridges is significantly less than the distance between spaced purlins 20 to increase the load carrying capability of corrugated sheet 12. The horizontally disposed sheet 16, screws 18, and connector portions 15 of the symmetrically corrugated sheet 12 of high tensile strength steel interact to form a truss-like structure extending generally parallel to the purlins intermediate ends of the span. This truss-like structure greatly increases the shear strength of the corrugated sheet 12.

[0045] If corrugated sheet 12 is 32 feet long, spanning over purlins 20 spaced apart 8 feet, the total expansion of sheet 12 is approximately 0.124 inches (⅛inch) as a result of a 50 degree Fahrenheit temperature change. The thermal expansion of one of the eight-foot spans is approximately 0.0312 inches ({fraction (1/32)}inch). The thermal expansion of steel sheet 12 generates popping sounds as a result of the rubbing action of one hard metallic surface on another.

[0046] As will be hereinafter more fully explained, an ideal sound deadening material positioned between the upper surfaces of purlins 20 and lower surfaces of steel sheets 12 for preventing the popping noises is a thin relatively soft, compressible sound absorbing material which permits relative movement of the upper and lower surfaces of the sound deadening material a distance of at least the distance the span moves as a result of thermal expansion or contraction. In the example above, assuming that pins 12c securing corrugated sheet 12 to purlins 20 securely attaches the sheet 12 to the intermediate supporting purlins 20, then the thermal expansion will be equally divided between the supporting purlins 20. This thermal expansion will cause the corrugated steel sheets 12 to buckle upwardly or downwardly, since the sheet 12 cannot move along its length due to being restrained by the supporting purlins. In the example above, the eight-foot span, when experiencing a fifty degree temperature change would expand approximately {fraction (1/32)}inch which would result in either a slight vertical movement of contact points between the steel deck 12 and purlin 20 which may result in a sudden impact or deformation of the steel sheet 12 at contact points with purlin 20. In the event that the steel corrugated sheet 12 is already in contact with surfaces of purlin 20, the thermal expansion may result in slight sliding action of surfaces in a horizontal direction. In either case, we have found that positioning sound deadening material between the lower surface of sheet 12 and the upper surface of purlin 20 alleviates the problem. The sound deadening material should be sufficiently resilient to permit relative movement between sheet 12 and purlin 20 in a horizontal or vertical direction by an amount sufficient to accommodate the thermal expansion of the span distance between purlins 20 of sheet 12. The materials hereinafter described are selected to provide a cushioning effect resulting from vertical movement which may result from slight buckling of sheets 12 as a result of thermal expansion and also to keep the surfaces separated to prevent generation of noise as a result of wiping action which may result from horizontal movement of lower surfaces of sheet 12 relative to contact points with purlin 20. Heretofore, vapor barriers, constructed of materials which have good resistance to the passage of water vapor and gasses have been positioned above and below corrugated sheets in decks. Such vapor barriers have included polyethylene film, asphalt saturated felt, metal foil and vinyl sheet material. These vapor barriers generally have hard impervious surfaces and consequently are not sufficiently resilient to permit deformation of the material vertically or horizontally to function as a sound barrier to eliminate the popping sounds hereinbefore described. It is important that the material be compressible to absorb energy as the deck expands or contracts. The sound deadening material functions as a resilient cushion or shock absorber.

[0047] Materials such as EPDM, Neoprene rubber, felt which is not saturated with asphalt or tar, and inorganic felt are soft, pliable, porous and generally noncombustible. These materials are sufficiently resilient, capable of being deformed by shear loading to permit movement of the lower surface of the material relative to the upper surface when oppositely directed forces are applied to upper and lower surfaces of the material. Further, the materials provide a cushioning effect and deform slightly when forces are applied generally perpendicular to upper and lower surfaces of the material.

[0048] Referring to FIGS. 1, 2 and 3 of the drawing, a strip 25 of sound deadening material is positioned to extend longitudinally of the upper surface of each purlin 20 for separating the upper surface of the purlin from the lower surface of the steel sheet 12. Strip 25 of sound deadening material is preferably formed of heavy glass reinforcing felt or polymeric membrane, such as vulcanized ethylene propylene diene terpolymer (EPDM). However, other elastomeric polymer materials which are generally classified as “M” class rubbers may be used. Further disclosure of the EPDM material can be found in U.S. Pat. No. 4,783,942 entitled “COMPOSITE ROOF DECK ASSEMBLY WITH POLYMERIC MEMBRANE ADHERED TO FIBERGLASS MAT.”

[0049] For maintaining the diaphragms performance and stiffness, the thickness of the sound deadening material 25 positioned between the upper surface of purlins 20 and the lower surface of corrugated sheet 12 and sheet 30 positioned above corrugated sheet 12 is preferably less than about ½inch.

[0050] Powder actuated pins 21 extend through valley 13 of corrugated sheets 12 of high tensile steel, through strip 25 of sound deadening material and the upper flange of purlin 20. Suitable power actuated pins for metal deck attachment are commercially available for ITW Buildex, product number BX14.

[0051] Referring again to FIGS. 1, 2 and 3 of the drawing, a sheet 30 of sound deadening material is positioned to cover ridges 11 of corrugated sheets 12 to separate upper surfaces of the sheet 12 from the lower surface of thermal insulation material 14. If the optional sheet of thermal insulation material is not utilized, sheet 30 of sound deadening material would engage the lower surface of mineral board 16 or any other material positioned therebetween.

[0052] As best illustrated in FIG. 4 of the drawing, each corrugated sheet 12 has side edges 12a and 12b which are positioned in overlapping relation to form joints between adjacent sheets 12 of corrugated material. Strips 26 of sound deadening material are positioned between the lower surface of edge 12a of one sheet and the upper surface of edge 12b of an adjacent sheet 12 such that the metallic surfaces on sheets 12 are separated by the strip 26 of sound deadening material. Side edges 12a and 12b preferably overlap about three inches and are secured together by pins 12c or sheet metal screws (not shown).

[0053] As best illustrated in FIG. 5 of the drawing, end edges 12e and 12f on adjacent sheets 12 are positioned one above the other to form overlapping joints separated by a strip 27 of sound deadening material and secured together by pins 12c′or sheet metal screws (not shown). Edges 12e and 12f preferably overlap about four inches.

[0054] In the embodiment of the invention illustrated in FIG. 6 of the drawing, corrugated sheet 12 is provided with side strips 36 and end strips 37 of non-metallic material, such as polyurathane foam, sprayed onto the lower surface and positioned to extend around the periphery of corrugated sheet 12. In the embodiment illustrated in FIG. 6, sound deadening strips 36 and 37 may be applied to upper and lower surfaces of the corrugated sheet. However, in most instances strips 36 and 37 can be formed on only one surface, such as the top or the bottom of the sheet such that a strip 36 is positioned between overlapping side edges of adjacent sheets and sound deadening strips 37 are positioned between adjacent surfaces of end edges of adjacent sheets 12 to prevent physical contact between adjacent metal surfaces on the sheets.

[0055] In the embodiment of FIG. 7, resilient molding strips 40 and 41 are positioned to extend around the periphery of each corrugated sheet 12 such that molding strips are positioned in substantially the same position as the sprayed-on strips 35 and 37 illustrated in FIG. 6 of the drawing.

[0056] Strips 25, 26, 27, 36 and 37 and sheet 30 of sound deadening material are a porous material which does not block passage of vapor and has a relatively soft sound absorbing characteristic in both its composition and surface finish.

[0057] It should be understood that while the best mode of the invention hereinbefore described relates to a composite roof deck constructed with high tensile steel, it should be appreciated that the problem exists with conventional assemblies constructed of mild steel decking and we contemplate the use of sound deadening material disclosed herein in other and further assemblies. Further, while a roof deck has been disclosed, it should be understood that the invention applies to floor decks, walls and partitions.

[0058] Terms such as “left,” “right,” “horizontal,” “vertical,” “up” and “down,” when used in reference to the drawings, generally refer to the orientation of the parts in the illustrated embodiment and not necessarily during use. These terms used herein are meant only to refer to relative positions and/or orientations, for convenience, and are not to be understood to be in any manner otherwise limiting.

[0059] It should be readily apparent that other and further embodiments of the invention may be devised without departing from the spirit and scope of the appended claims.