US 3733231 A
Description (OCR text may contain errors)
y 9 3 E. J. RUTKOWSKI ETAL 3,733,231
WALLBOARD ATTACHMENT Filed June 16, 1971 2 Sheets-Sheet 1 INVENTORS Edwu rd J. Ru'rkowski Flg-s BY Joseph W. Schneller ATTORNEY y 15, 1973 E. J. RUTKOWSKI ETAI- 3,733,231
WALLBOARD ATTACHMENT Fi l e d J u n e l 6 l 9 '71 United States Patent 3 Claims ABSTRACT OF THE DISCLOSURE Wallboard afiixed to studs or trusses by a strip of metal foil with hot melt adhesive on both surfaces, disposed between the board and the framing member and held there firmly while heating the foil with an electric current.
The usual attachment of wallboard to framing members involves fasteners disposed through the board and into the framing member, leaving an unsightly fastener head portion exposed which must somehow be covered, hidden or camouflaged.
It is an object of the present invention to provide an improved fastening means for wallboard with no fasteners extending through the board.
It is a further object to provide a very rapid means for firmly affixing a wallboard back face against a framing member front face.
It is a still further object to provide a novel means for attachment of wallboard which is particularly adapted for manufactured homes.
These and other objects and advantages of the invention will become readily apparent from the following description and the drawings in which:
FIG. 1 is an isometric view of a hot melt coated metal foil strip attaching means formed in accordance with the invention.
FIG. 2 is an isometric view of a truss having the strip of FIG. 1 attached to the bottom surface.
FIG. 3 is an enlarged view of the end portion of the truss of FIG. 2.
FIG. 4 is an isometric view of a plurality of the trusses of FIG. 2 during attachment thereof to a ceiling board.
FIG. 5 is a view similar to FIG. 3 of a truss having a modified strip attached to the bottom surface.
Referring to FIG. 1 there is shown a board attaching strip consisting of a steel foil 12 of 1 mil thickness, one inch width and a length which is about three inches longer than the length of board with which it is intended to be used, on each face of which said foil 12 there is adhered a thin adhesive coating 14 of a hot melt type of adhesive.
Each adhesive coating 14 has a thickness of about .013 inch, and is equal in width to the width of foil 12. The adhesive coatings 14 completely cover each face of the foil 12 throughout that portion of the length equal to the length of a board with which it is to be used, leaving an uncoated portion 16 of foil 12 of about one and a half inches in length at each end thereof. Coatings of about .010 inch and .025 inch have also Worked well.
In FIG. 2, strip 10 is shown affixed by staples 18 to the bottom face 20 of a bow string truss 22 with coating 14a contacting the bottom face 20, coating 14b being exposed. The truss bottom face 20 is equal in length to the length of the coating 14. The staples 18 are placed about every four feet, and function as a temporary means of maintaining strip 10 in proper relation to bottom face 20.
Enlarged view, FIG. 3 shows the hot melt adhesive coatings 14 coextensive with the truss 22. Also shown is the preferred form of steel foil 12 with a plurality of perforations 24 through which the coatings 14 of two op- 3,733,231 Patented May 15,, 1973 ice posite sides are in contact with each other and need not rely solely on the adhesive to metal bond.
In FIG. 4, a plurality of trusses 22, with strips 10 stapled thereunder, are disposed with the exposed coating 14b resting on the top surface 26 of wallboard 28, or preferably, as shown, on the polyethylene film vapor barrier 29 disposed over the entire top surface 26. Suitable spring loaded electrical clips 30 are afiixed to each uncoated portion 16, with electrical leads 32 therefrom to bus bars 34. In the embodiment shown, three strips 10 are connected to one bus bar 34 at the near end and a second bus bar 34 at the far end. The bus bars are connected to a suitable power supply (not shown).
The wallboards are firmly supported thereunder, as by a roller conveyor in a manufactured home plant (not shown). The trusses 22 rest throughout their length firmly pressing the entire length of strip 10 against the vapor barrier 29 on the board top surface 26. The trusses may be of the common form of a bow string truss with a straight bottom chord 36, a bowed top chord 38 and a plurality of gussets 40, adjoining the bottom and top chords. A pair of let-in stringers 42, with notched bottom edges, extend perpendicular to trusses 22, extending between the upper and lower chords, with the notches 44 engaging the bottom chords 36.
In order to firmly afiix wallboard 28 to the trusses 22, an electric current is passed through the foil 12 of each strip 10, sufficient to heat the foil and raise the temperature of the hot melt adhesive to about 250 F. Preferably a relatively uniformly distributed load, about one or two pounds per square inch, is applied throughout the length of truss 22, tending to squeeze slightly the strip 10 throughout its length, assuring intimate contact of the strips to the board and trusses, during heating. An alternating current may be, initially, 60 amperes, with 45 volts, with a twelve foot strip 10 of an initial total resistance of about 0.4 to 0.5 ohm. As the foil 12 becomes heated the resistance increases and the amperage is proportionately reduced. With the above said voltage and amperage, a total time of about 50 seconds is required to soften the hot melt coatings 14 and the polyethylene film of the vapor barrier 29 immediately thereunder, and permit the softened materials to flow and effectively wet the truss bottom face 20 and the wallboard top surface 26. The resulting melted and subsequently cooled polyethylene still provides a vapor seal equal to or better than the original film.
As mentioned, the length of the truss bottom face 20 and of the coatings 14 is equal to the length of the wallboard 28. Care should be taken to dispose the strip 10 so that the hot melt coatings 14 extend exactly between the extents of the truss 22 and the wallboard 28. If the coatings 14 do not extend to the edges of the truss and wallboard, the truss and wallboard will be burnt by the hot uncoated portion 16. If the coatings 14 extend beyond the edges of the truss and wallboard, the coatings 14 become excessively hot and flame, which flame may spread and cause damage.
The strip 10 may be used on ceiling board 28 which has a compatible plastic vapor barrier 29 thereover, or on other board without a vapor barrier thereover. Instead of trusses 22, the board may be attached to studs in vertical walls. The wallboard 28 may be a paper covered gypsum wallboard, a wood fiber board, asbestos cement board, plywood, or board of other material. With the preferred gypsum wall'board, the bond of the strip 10 to the paper back face of a wallboard is stronger than the internal strength of the paper, and if a gypsum board, bonded to a truss in accordance with the invention, is forcibly removed therefrom a portion of the paper surface will be removed from the board.
The strip is preferably manufactured and sold in the form of a continuous length of a plurality of strips 10, having, for example, twelve foot lengths with coatings 14 and, alternating therewith, three inch strips of bare foil, which when cut in half form two uncoated portions 16. The continuous length of strips 10 may conveniently be fomed into a roll for ease of storage and handling.
Although the preferred form of strips 10 is of a 'width equal to the truss Width, or other framing member width, with which it is to be used, the strip 10 width may be narrower. The coating 14 described was of about .013 inch thickness, however substantially thinner or thicker coatings can be used. Many other characteristics described may be varied dependent on the results desired, including the resistance, voltage, amperage and the time of heating, as will be readily understood.
In FIG. 5, a modified board attaching strip 50 is shown disposed between truss 22 and wallboard 28. Strip 50 is similar to strip 10 except the adhesive coatings 52 extend beyond the edges of the truss and wallboard, coextensive with the foil 54. Special electrical clips '56 are shown with a multiplicity of penetrating teeth 58, which will penetrate the adhesive coating 52 and provide contact with foil 54. Clips 56 are formed to completely enclose the entire portion of strip 50 which extends beyond the truss and wallboard to prevent flames developing from the heated ad hesive.
The hot melt adhesive, of which coating 14 is formed, may be any of many thermoplastic substances, composed of a thermoplastic polymeric material and a diluent system. Hot melt adhesives may be generally defined as 100% non-volatile thermoplastic substances which exist in a solid form at room temperature and which becomes sufficiently fluid or tacky at elevated temperatures to be employed as adhesives. The hot melt adhesives of the invention preferably remain solid and unafiected by heat up to about 150 R, which temperatures are often developed in the plenum area of a manufactured home, such as a mobile home, but develop definite fluidity and tack at about 250 F. Examples of resins which may be used for this invention are polyethylene, polyvinyl acetate, ethylene vinyl acetate copolymers and the like. The diluent systems, usually a blend of materials such as wax, plasticizer, heat stabilizer, dyes, and inert fillers and extenders, make it possible to adapt the properties of the polymer to the characteristics desired.
What is claimed is:
1. The method of fastening wallboard to framing members comprising the steps of disposing a wallboard fastener strip between the back face of said wallboard and the face of a framing member, said wallboard fastener strip comprising an elongate metal foil strip of substantially uniform cross section throughout with a substantially uniform coating of hot melt adhesive on each surface thereof, said coatings being coextensive with said foil strip throughout the full width thereof and substantially the full length thereof, pressing said wallboard, said fastener strip and said framing member together, attaching an electrically conductive clip to each end of said fastness strip, covering all of both surfaces of said strip with said wallboard, said framing member and said clips whereby substantially no surface area of said strip is exposed to the atmosphere, passing sufiicient electric current through said foil to soften said hot melt adhesive, maintaining said adhesive soft sufficiently long to acquire a bond to said wallboard and said framing member and terminating said electric current.
2. The method of claim 1 wherein said fastener strips are stapled to the face of said framing member.
3. The method of claim 1 wherein a continuous thermoplastic vapor barrier film is placed over the back face of said wallboard between said wallboard and said framing member in contact with said fastener strip and wherein said heated softened adhesive softens said thermoplastic film and said softened thermoplastic film bonds to abutting elements.
References Cited UNITED STATES PATENTS 3,576,091 4/1971 Skull et a1. 156-275 X 3,542,619 11/1970 McManus 156-275 EDWARD G. WI-HTBY, Primary Examiner US. Cl. X.R.