US3506088A

US3506088A - Metal dual panel sound insulating structures

Info

Publication number: US3506088A
Application number: US718039A
Authority: US
Inventors: Philip E Sherman
Original assignee: PHILIP E SHERMAN
Current assignee: PHILIP E SHERMAN
Priority date: 1968-04-02
Filing date: 1968-04-02
Publication date: 1970-04-14
Anticipated expiration: 1987-04-14

Description

1 14 1970' I Pl-EIJSHERMAN 3,506,088 METAL DUAL :PANELFVSOUNDINSULATING STRUCTURES Filed April 2, 1968 Apri 2 Sheet-Sheet 1 7 INVENTOR. P/nfi b E. Sherman BY I:

United 1 States Patent 16 Claims ABSTRACT OF THE DISCLOSURE A metal dual panel sound insulating structure comprising a main frame member and a removable floating frame member separated from each other and telescopically fitting together, said main panel frame member having spaced wooden stiles and rails forming a face span of different size and thickness as compared to the face span of the floating frame. member, said face spans each being covered with a metal face panel which is turned over the adjacent peripheral side edges thereof, said independent face spans each being covered with layers of different and independent sound insulating materials, said panel members being linked flexibly into an integral sound insulating structure.

BACKGROUND OF THE INVENTION Field of the invention The invention relates generally to sound insulating structures, and it has particular relation to doors, partitions and windows having separated panel members covered with a sheet metal skin, said panel members having independent internal free spans of different sizes and thicknesses and a total and complete separation of their rigid parts, whereby sound vibrations striking one panel member cannot be transmitted directly into the other panel member without first penetrating said panel member and the several layers of varying thicknesses of different sound vibration insulating materials.

In the prior art involving dual panel sound insulating structures there is a direct area of rigid contact in the opposing frame structures, providing a direct passageway for vibration of sound waves, thereby reducing the effectiveness as a sound insulating structure. Such direct passageways have been obviated by the present invention, and the need for a third intermediatev frame has also been eliminated.

SUMMARY An object of the present invention is to provde light weight metal sound insulating structures of the character described, which are simple, eflicient and economical to manufacture and install and acoustically better than the more complex structures.

Another object of the invention is the provision of a fire resistant and/or fire proof structure of the character described, which is compact, similar in size and appearance to a conventional metal clad door or movable partition, and which is easy to install, open, close and remain stable.

A further object of the invention is to provide a dual panel soundproof structure wherein its panel members are separated by an air passageway capable of preventing warping during changes in the surrounding atmospheric conditions.

Another object of the invention is the provision of a dual panel soundproof structure made of metal which has exceptional stability under conditions of extreme stresses. 2

A further object of the invention is to provide a soundproof structure of two separate metal panel members,

each of which is free of internal stiffeners or spreaders and free of direct contact therebetween, whereby each of the panel members has a limp construction, which, when assembled, has an increased combined weight that becomes more limp from a soundproofing standpoint.

Another object of the invention is to provide an arrangement of different sound insulating materials on the independent different inside panel members, particularly over their respective free spans, thereby causing the natural frequency responses of each said panel members to be disharmonic and react differently and independently of each other to achieve a better soundproof barrier therebetween.

A further object of the invention is to provide a sound insulating structure formed of separated dual panel members which, when combined, have no rigid point of contact whatsoever, but, because of the construction, provides a limp and flexibly linked structure having the qualities and characteristics of absorbing sound waves that come into contact therewith.

Another object of the invention is the provision of a sound insulating structure formed of separated dual panel members which can be moved with respect to each other even after assembly, which flexibility attests to the limpness of the assembled structure and improves the soundproofing qualities thereof.

A further object of the invention is to provide a sound insulating structure of a separated dual panel construction which can be easily and quickly disassembled, when desired, to replace or substitute new and improved sound insulating materials without requiring the complete destruction and rebuilding thereof.

Other and further objects and advantages of the invention reside in the detailed construction of the two panel members and their method of assembly, which result in simplicity, economy and efficiency, wherein preferred embodiments of the. invention are shown, reference being had to the accompanying drawings, forming a part hereof, wherein like numerals indicate like parts, in which:

DRAWINGS FIGURE 1 is a front elevational view of a sound insulating structure in the form of a door, which has been constructed in accordance with the principles of the invention, and which has parts broken away to better illustrate the features thereof;

FIGURE 2 is a vertical sectional view of the structure shown in FIGURE 1, thesa'me having been taken substantially along the line 2-2 thereof, looking in the direction of the arrows, and showing said door being mounted in a conventional door frame with appropriate sealing gaskets to illustrate the sealing of said door against said door frame;

FIGURE 3 is a cross-sectional view of the structure shown in FIGURE 1, the same having been taken substantially along the line 3-3 thereof, looking in the direction of the arrows;

FIGURE 4 is an enlarged fragmentary detailed view of the door and header shown in FIGURE 2;

FIGURE 5 is a fragmentary vertical sectional view of a modification of the structure shown in FIGURE 2, wherein the bottom is constructed to fit a flat sill;

FIGURE 6A is a fragmentary cross-sectional view of a modification which the invention may assume, wherein a pair of swinging doors are shown with their astragal detail for sealing the intermediate space therebetween; and

FIGURE 6B is a fragmentary cross-sectional view of one of the doors shown in FIGURE 6A, showing its vision port and the details of its construction.

3 DESCRIPTION OF THE INVENTION Referring now to FIGURES 1 through 5, both inclusive, there is shown the construction of a sound insulating structure in the form of a metal door or metal clad door, which is approximately 2% inches thick, having a width between 3 and 6 feet and a height of between 7 and 14 feet, comprising a main frame panel member and a floating frame panel member 12. The above thickness dimension of the door shows clearly the improvement in the present sound insulating structure since the thickness of the door of the present invention is less than one-half the thickness and weight of conventional present day metal clad or steel doors while its sound insulating properties are substantially as great if not greater in most instances.

THE MAIN FRAME The main frame member 10 is always the heavier or hinge side of the door, and comprises stiles 16 and 18 (see FIGURE 3) and rails 20 and 22 (see FIGURE 2) made of wood, chipboard or any other suitable material, which stiles and rails are formed into an integral rectangular frame member reinforced at its corners with suitable metal fasteners 24, such as corrupated nails (see FIGURE 1). The

stiles

16 and 18 are notched, grooved or recessed, as indicated at 19 and 21, respectively. The top rail 20 is notched, grooved or recessed, as indicated M25, and the bottom rail 22 is also notched, grooved or recessed, as indicated at 27, for reasons hereinafter to be explained.

There is an opening or free span 26 centrally of the main frame member 10 formed by the

stiles

16 and 18 and

rails

20 and 22. It will be noted that the outside peripheral surfaces of the stiles 16 and 18 (see FIGURE 3) and rails 20 and 22 (see FIGURE 2) are tapered or inclined downwardly and inwardly, as indicated at 29, at an angle acute to the outer face surface thereof. The

stiles

16 and 18 and

rails

20 and 22 are assembled within a preformed sheet metal panel member 28, which completely covers the central opening 26. The peripheral edges of the preformed sheet metal panel 28 have integrally formed inturned flanges 31 and 33 (see FIGURE 3) covering the outer side surface of the

stiles

16 and 18, and also integrally formed inturned flanges 35 and 37 (see FIGURE 2) covering the top and bottom surfaces of the

rails

20 and 22, respectively. It will be noted in FIGURES 2 and 3 that the integrally formed

flanged edge portions

31, 33, 35 and 37 of the sheet metal panel member 28 are tapered or inclined inwardly at an angle acute and corresponding to the angle of inclination of the peripheral surfaces of the

stiles

16 and 18 and the

rails

20 and 22, whereby such surfaces fit snugly and are capable of being permanently glued together. The inward edge of the flange 35 is again turned inwardly at substantially a right angle to form a second or edge flange 41 extending further inwardly and parallel to its main face panel 28 (see FIGURE 4).

The main frame member 10 has an extruded U-shaped rubber channel member 60 glued into the notch or recess 25 of the rail 20 and within the second flange 41 of the main face panel member 28. It will be noted that the arms of the channel member 60 open inwardly to provide a sound insulated receiving slot 62 (see FIG- URE 4).

The

stiles

16 and 18 are each provided with an extruded U-shaped

rubber channel member

64 and 66, respectively, whose arms open inwardly to provide a sound insulated receiving slot 68 (see FIGURE 3).

A layer of viscous sound vibration damping material 70 is applied to the inner surface of the sheet metal panel member 28, and a layer of paper covered polystyrene 72 of about the same thickness as the layer of viscous sound vibration damping material is now positioned over said layer of damping material 70, said layers filling less than one-half of the thickness of the free span 26. A relatively thick layer, as. compared to the layers of viscous damping material 70 and polystyrene 72, of fiber glass 74 is next positioned over the layer of polystyrene 72, completely covering the same and completely filling the remainder of the free span 26. A limp septum or sheet of conventional roofing tar paper material 76 is laid over the top surface of the fiber glass 74, and has its edges secured to the inner surfaces of the

stiles

16 and 18 and

rails

20 and 22 by metal fastener members, such as staples 78.

THE FLOATING FRAME The floating frame or sub-frame 12 consists of a single sheet metal face panel member 100, whose upper edge is flanged inwardly at right angles to its face, as indicated at 102. The inner end of the flange 102 has a portion turned upwardly and parallel to the floating face panel member 100, as indicated at 104 (see FIGURE 4). The lower end of the floating face panel member extends downwardly in alignment with the bottom of the door, and it has a right angle reinforcing bracket 106 welded or otherwise permanently secured thereto. The reinforcing member 106 has a vertical arm welded to the inner edge of the face panel 100 and a horizontal arm extending inwardly at right angles thereto, said arms being substantially of equal length. The horizontal arm extends inwardly a distance approximately the length of the top flange 102 (see FIGURE 2). The sides of the floating face panel member 100 are turned inwardly to form integrally extending flanges 112 and 114 (see FIGURE 3). The flange 112 has its inner end turned outwardly, forming a short flanged edge portion 116 extending outwardly in a plane at right angles to the flange 112 and parallel to the plane of the floating face panel 100. The flange 114 likewise has its inner end turned outwardly in a plane at right angles to the flange 114 and parallel to the plane of the face panel 100. Therefore, the floating frame member 12, when placed in a horizontal position with its single sheet metal face panel 100 on the floor, resembles an open top pan with narrow peripheral

side edge flanges

104, 116 and 118, said flanges extending in a single plane spaced from and parallel to the plane of the face panel 100. Obviously, the floating frame member 12 has a greater free span than the free span of the main frame member 10 since it has no stiles or rails mounted therein.

A layer of sheet rock 121 is glued to the inner surface of the face panel member 100 except for a relatively short distance adjacent it's peripheral edge flanges. The space between the edges of the sheet rock 121 and the adjacent edge flanges of the floating panel member 100 are filled with a viscous sound vibration damping material 123, which may be a conventional caulking compound of the like. The damping material 123 from the top surface of the sheet rock to the outer ends of the

flanges

112 and 114 is tapered, as best shown in FIGURE 2.

A blanket of limp sheet material 125, consisting of a mixture of shredded cotton and shredded paper, which is a conventional material sold under the trademark Tufllex, is mounted over the layer of sheet rock 121 and the tapered edges of the damping material 123. Obviously,

the edges of the blanket 125 must be trimmed to fit the tapered edge of the sound damping material 123 to prevent bunching at the point where such materials overlap. Thus, the edges of the sheet rock 121 and blanket 125 are separated from their adjacent peripheral metal side flanges by a trough filled with caulking compound 123. The external arms of the bracket member 106- are covered with a protective layer of cellular foam rubber padding 138 (see FIGURE 2), which is capable of breathing, thereby preventing warpage in the assembled door structure with changes in surrounding atmospheric conditions.

ASSEMBLING OF THE MAIN FRAME AND THE FLOATING FRAME The separated dual panel members forming the sound insulating structures, which comprise the main frame mem- 'ber and the floating frame member 12, respectively, are now ready to be assembled with all of their respective internal treatment having been applied.

The main frame member 10 is positioned horizontally with its face panel 28 facing downwardly, whereupon it is now in position and ready to receive the floating frame member 12.

The floating frame member 12 with its outer face panel 100 extending upwardly, is now ready to be slidably inserted longitudinally through the bottom of the main frame member 10 and over its rail 22. The

opposite side flanges

116 and 118 are fitted manually into the slots 68 of the U-shaped channel members 64 and 66 (see FIG- URE 3), and the assembled frame member 10 by means of its external flanges running in the receivingslots of the rubber channel members and being passed over the tar paper, leaving a space therebetween, until the top flange member 104 is fitted snugly into the slot 62 of the U- shaped channel member 60 mounted in the top rail 20.

When the

frame members

10 and 12 are so assembled, the rectangular edge strip 132, which has an angular metal reinforcing bracket 134 glued to its two inner sides, is now ready to be positioned in the rectangular notch 27, as best shown in FIGURE 2. The inner edge strip 132 and the longer arm 136 of the bracket 134 are drilled with a series of longitudinally spaced holes to provide means for receiving a series of metal fastening members, such as wood screws 140 that extend into the bottom rail 22, as best shown in FIGURE 2. The edge strip 132 solds the entire floating frame member 12 in its working position and removably secures the two

independent frames

10 and 12 into an integral sound insulating structure that has an internal air space covering the height and width of its entire inner surface area. Obviously, by removing the wood screws 140, the bottom edge strip 132 and its internal metal bracket 134 can be removed readily as a unit. With the bottom edge strip 132 and its integral bracket 134 removed, the assembled floating frame 12 may be withdrawn longitudinally from the main frame member 10 through its open bottom for repair and/ or replacement of its sound insulating materials, etc.

It will be noted that, in its assembled position, the main frame member 10 and the floating frame member 12 are flexibly linked together since all of its protruding flanges are mounted within U-shaped rubber channel members, which are flexible. It will also be noted that there is no direct contact between the rigid portions of the main frame member 10 and the floating frame member 12. Hence, there can be no direct transmission of sound vibrations from one frame member to the other frame member. Any sound vibrations striking the outer surfaces of the

panel members

28 and 100 must be passed through the various non-harmonic damping and soundproofing materials. Referring to the assembly, as best shown in FIGURE 3, the air space 135 is shown substantially coextensive with the surface area of the tar paper membrane material 76, providing an additional sound insulating barrier, and allowing the structure to breath with different atmospheric conditions that may prevail on the outer face panels. This construction also makes the structure virtually warp-proof, as air can pass through the entire center of the door when assembled and through the cellular foam rubber strip 138 thereby counter-acting the outside pressures.

PERIPHERAL DOOR SEALS There is shown in FIGURES 2 and 4 a pair of spaced sealing

gaskets

150 and 152. The sealing gaskets are made of a very soft foam rubber suitably encased in a plastic casing 156, having end portions 158 extending outwardly therefrom to provide suitable fastening means in the form of flanges.

The gasket 150 is suitably mounted over the end of a door stop 161, and has its flanged end portions secured glued together in a staggered arrangement and enclosed on their two outer sides by a right angled metal bracket 177. The bracket 177 and the door stops 161 and 171 are drilled to provide a series of longitudinally spaced holes through which they maybe suitably secured to the header 165 by means of countersunk wood screws 179. The staggering arrangement of the door stops 161 and 171 and their

respective sealing gaskets

150 and 152 causes the gasket 150 to be compressed against the main frame 10 and the gasket 152 to be compressed against the floating frame 12.

The opposite sides of the door are also equipped with pairs of spaced sealing gaskets and 182, which, in turn, have their flanged end portions secured by staples 184 to staggered door stops 186 and 188. The door stops 186 and 188 are glued to the conventional door frame 167 and to each other, but it is obvious that they may also be mounted by other suitable fastening means, such as wood screws, nails and the like. The door stops 186 and 188 each have their outer sides covered by a suitable metal right angle bracket 189, as best shown in FIGURE 3, which is glued or otherwise suitably secured thereto.

The bottom edge of the door, as shown in FIGURE 2, is provided with a pair of corresponding spaced gasketed door seals 192 and 194 adapted to engage a sloping sill 196. These gasketed door seals are secured to the bottom of the inner edge strip 132 by staples 198 through their own flanges.

Referring now to FIGURE 5, there is shown the bottom of a door equipped with a conventional drop seal 201, which is particularly adaptable for use in connection with a flat sill 203. The drop seal 201 is slidable and drops down when the door is in its closed position and retracts upwardly when the door is opened.

DUAL PANEL SWINGING DOORS There is shown in FIGURE 6A a fragmentary view of an astragal detail incorporated as a modification of the present invention in the form of a pair of swinging

doors

240 and 242 in which each is equipped with a vision port or window 244, as shown in detail in FIGURE 6B.

The vision port or window 244 consists of two independent panes of

plate glass

250 and 252 secured in internal separated

frames

254 and 256 mounted one on the main frame member 10 and the other on the floating frame member 12. The internal separated

window frames

254 and 256 have a recess or slot cut therein, which is fitted with a U-shaped rubber channel member 266, having its arms extending inwardly. The panes of glass 250- and 252 are mounted with their peripheral edges extending into the slots 264. Across the inner surfaces of the inner peripheral edges of the

window frames

254 and 256 and between the spaced

glass panes

250 and 252 there is glued a felt liner 268. The

external window mouldings

269 and 271 are positioned parallel to the outside of the face panels, covering the outside legs of the rubber channel members 266 and are secured to the

window frames

254 and 256, respectively, by wood screws 273, thereby holding the panes of glass in position. The window frames 254 and 256 have a rubber strip 275 extending inwardly from the inner side of the felt liner 268 to the edge of the tar paper 76.

The details shown in FIGURE 6A disclose the internal construction of the

doors

240 and 242, which are'identical to the single door shown in FIGURES l to 4, both inclusive. Manifestly, there is no rigid connection between the main frame 10 and floating frame 12 of each door or any of their component parts.

The floating frame member 12 has an astragal 270 mounted thereon by means of a series of longitudinally spaced metal self-tapping screws 272. The astragal 270 spans the space between said pairs of swinging

doors

240 and 242, but is not fastened to the door 242 against which it abuts and overlaps. The astragal 270 consists of a metal plate having a wooden strip 274 glued or otherwise mounted on the inner side thereof and extending outwardly from the door 240 towards the opposite door 242. A sealing gasket 276, having end flanged portions 278 is mounted on a plywood strip 274 by means of staples 282. The plywood strip 280 is mounted on the wooden strip 274 in such manner that the flanged portion 278 and the staples 282 are secured therebetween. When the

doors

240 and 242 are in their closed position, the sealing gasket 276 abuts against the corner of the main frame member of the door 242, which has the U-shaped channel member 66 mounted therein. It will be noted that the

doors

240 and 242 are completely separated by an air space 288 between the floating frame members except for the overlapping and abutting end of the astragal 270.

VISION PORTS Where an airlock is required, which involves the application of two spaced doors, such doors should be of different thicknesses with different natural frequencies so as to obtain the maximum sound reduction.

It will be obvious that in an air lock arrangement the doors mounted at the opposite ends of the air lock are each provided with a vision port or window. Such vision port or window tends to be more of a custom item, varying considerably in detail from job to job. However, the approximate sound transmission loss required should preferably be included. Such vision ports or windows are used extensively for recording, radio and TV studios and where quiet is required in industry, schools and colleges. Many plants and laboratories, especially those investigating and testing the characteristics of engines, large motors, etc. put them in soundproof rooms and find the ability to observe the equipment in operation through the vision ports or windows most useful. These window or vision ports, which are frequently embodied in a single door construction, such as those previously described, are made of two or more panes or lites of plate glass, detuned, mounted in frames either one piece or split, on opposite sides of the door.

The usual size of such vision ports is ten inches by ten inches, and they must be mounted a distance of at least seven inches away from the top or side edges of the door. This is done so that the vision port frames will not encroach upon the frames of the door, and to allow a cavity of sufficient size to permit the necessary acoustical treatments to be applied.

The maximum size for good acoustical results is two hundred and fifty square inches in area. The vision ports or windows must also be placed low enough in the door for short people to see through them. The window lites or panes should be made of plate glass having a thickness of not less than one quarter of an inch, but when a combination of different thicknesses is used, such as threeeighths of an inch for one glass and a quarter of an inchfor the other glass, a better acoustical result is obtained. The window frame between the spaced glass panes should be covered with a felt liner, which may be glued to said surface area, which felt liner acts as an absorber. The air space between the two panes of glass also improves the acoustical properties of the vision port.

UTILITY With the door in this same position, its floating frame may be moved longitudinally or laterally with respect to the main frame. Such movement shows the total and complete disconnection and separation of the panels and the enhancement of the soundproof qualities of the separated dual panel construction. It also establishes without doubt the limpness of the doors of the present invention against the rigidity of the conventional soundproof doors of the prior art.

Another outstanding feature of the invention is the ability of the assembled sound proof structures to breath, which is due to the air space 135 that extends substantially coextensive with the surface area of the tar paper membrane material 76 and the air passable foam rubber insulating strip 138 at the bottom of the door and between it and the removable edge strip 132.

The further utility of the present structures may best be shown by the following test conducted as an actual working installation by an internationally known and recognized Government testing laboratory:

SOUND TRANSMISSION CLASS RATING 2%!) ASTM E -6 6T: steel door 30 1,000 44 1,250 41 1,600 40 2,000 42 2,500 46 3,150 49 4,000 5O STC 44 Weight per square foot 12 pounds.

DEFINITIONS The terms sound vibration insulating material,

sound damping and vibration damping have been used to denote materials and methods used to substantially increase that which the physicist calls sound transmission loss, and includes such viscous materials as conventional compounds for caulking and the like.

The term limp sheet material has been used to denote any sheet material, such as a felt liner, tar paper, a mixture of shredded paper and shredded cotton, roofing materials of the asphalt type, paper backed plastic fibrous materials, such as polystyrene, etc.

The term floating frame is used to indicate that the thinner frame is capable of movement longitudinally and/ or laterally upon the application of pressure with respect of the other or heavier frame member even after assembly.

The term flexible is used to denote that the soundproof structures are bendable even after assembly, and the term flexibly linked is used to denote that the dual panels are movable or shiftable with respect to one another even after assembly upon the application of pressure at a peripheral edge thereof.

What I claim is:

1. A sound insulating structure comprising a main panel member and a floating panel member, said main panel member having a wooden frame consisting of spaced stiles and spaced rails providing an open free span centrally therethrough, a face panel of sheet metal attached to said wooden frame and closing said free span, a plurality of layers of different sound vibration insulating materials applied to the inner surface of said face panel and covering said free span, means including insulated channel recesses along three sides for receiving extending edge flanges and a recess along its remaining side for receiving an edge strip, said floating panel member comprising a sheet metal face panel having upwardly extending peripheral flanges about its periphery, said flanges on three sides having means in the form of extending edge flanges adapted to be received within the insulated channel recesses on corresponding sides of said main panel member, a recess on its remaining side for receiving an end of an edge strip, and an edge strip adapted to fit into the recesses on the remaining side of said main panel member and said floating panel member for holding said panel members together into a unitary sound insulating structure.

2. The invention defined in claim 1, wherein the recess along the remaining side of said floating panel member is provided with a layer of breathable sound insulating material adapted to engage the adjacent surfaces of said edge strip when the same is mounted therein.

3. The invention defined in claim 1, wherein the different sound vibration insulating materials covering the free span of said main panel member comprises viscous damping material, polystyrene, fiber glass and tar paper, and wherein the layers of different sound vibration insulating materials covering the inner face of said floating panel member comprises sheet rock and a blanket consisting of a mixture of shredded cotton and shredded paper.

4. The invention defined in claim 1, wherein the edge band is mounted removably so that said panel members may be separated for repair or replacement of said sound insulating materials.

5. The invention defined in claim 1, wherein the outer sides of said stiles and rails are inclined inwardly at an angle acute to the plane of its face panel side.

'6. The invention defined in claim 1, wherein the sheet metal face panel encloses two adjacent sides of said stiles and rails. I

7. The invention defined in claim 1, wherein the inner surfaces of said sheet metal face panel closing said free span in said main panel member is covered with a first layer of viscous sound damping material, wherein the first layer of sound damping material is covered with a second layer of limp sheet material, wherein the second layer of limp sheet material is covered with a third layer of fiber glass and wherein the third layer of fiber glass is covered with a fourth layer of limp sheet material, and wherein the inner face of said floating panel member is covered except for a marginal border area with a layer of sheet rock, wherein the marginal border area is covered with a layer of viscous damping material and wherein said layers of sheet rock and marginal areas of viscous damping material are covered with a blanket of a mixture of shredded cotton and shredded paper.

8. The invention defined in claim 1, wherein the inner ends of said peripheral flanges of said face panel of said main panel member are turned inwardly to enclose the inner sides of said U-shaped channel insulating members.

' 9. The invention defined in claim 1, wherein the slots in said U-shaped channel members are open inwardly in a single plane spaced from and parallel to said sheet metal face panel of said main frame member and said edge flanges on said floating frame member are in a single plane spaced from and parallel to the plane of said face panel thereof, whereby said floating frame member may be mounted telescopically on said main frame member when said edge flanges of said floating frame member are secured in said receiving slots of said U-shaped channel members of said main frame member.

10. The invention defined in claim 3, wherein the layer of sheet rock covering the inner surface of the floating frame face panel member is smaller than its surface area, forming a peripheral marginal space between the edges of the sheet rock and the edge flanges of the floating frame face panel, said peripheral marginal space being filled with a viscous sound vibration damping material.

11. The invention defined in claim 7, wherein the inner edge of the viscous sound vibration damping material is tapered upwardly and outwardly towards the top of said side flanges and the adjacent edges of the blanket of shredded cotton and shredded paper is tapered inwardly and downwardly from said side flanges, whereby the overlapping edges of said blanket will overlay said sound vibration damping material in the plane of said blanket.

12. The invention defined in claim 7, wherein the face panel of sheet metal attached to said stiles and rails has edge flanges inclined inwardly at an angle acute to the plane of its face panel.

13. The invention defined in claim 7, wherein the second layer of limp sheet material in the main panel member is polystyrene and the fourth layer of limp sheet material is roofing tar paper.

14. The invention defined in claim 9, wherein the plane of said slots in said U-shaped insulated channel members is spaced a greater distance from its face panel than the plane of said edge flanges is spaced from its face panel member.

15. The invention defined in claim 9, wherein the plane of said edge flanges of said floating frame member is spaced inwardly from the inner surface of said sound insulating materials, whereby when said panel members are fitted telescopically together there is an air space separating the innermost surfaces of said sound insulating materials of said main frame member and said floating frame member.

16. The invention defined in claim 13, wherein the layer of polystyrene is covered with paper on opposite sides and the peripheral edges of the roofing paper are fastened to the wooden frame of said main panel member.

References Cited UNITED STATES PATENTS 2,079,878 5/1937 Sabine. 2,880,471 4/1959 Von Munchhausen. 3,051,260 8/ 1962 Eckel. 3,120,295 2/ 1964 Lemmerman. 3,121,262 2/1964 Loncoske. 3,23 5,029 2/ 1966 Lemmerman. 3,273,297 9/ 1966 Wehe 52-404 3,319,738 5/1967 Wehe.

ROBERT S. WARD, In, Primary Examiner US. Cl. X.R.