Acoustical isolation floor underlayment system

Abstract

An acoustic isolation medium configured for placement between a subfloor and a finished floor with a poured underlayment, includes a first layer being a sound reduction mat disposed upon the subfloor, a second layer placed upon the first layer and being one of a sheet of fibrous material and a web of hi-density limp mass material with a high internal damping coefficient, and a third layer placed upon the second layer and being the other of a sheet of the fibrous material and a web of the hi-density limp mass material.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a fragmentary top perspective view of a floor including a preferred embodiment of the present acoustic underlayment system;

FIG. 2 is a schematic vertical section of the underlayment system of FIG. 1;

FIG. 3 is a schematic vertical section of an alternate embodiment of the underlayment system of FIG. 1;

FIG. 4 is a schematic vertical section of a second alternate embodiment of the underlayment system of FIG. 1; and

FIG. 5 is a schematic vertical section of a third alternate embodiment of the present underlayment system.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIGS. 1 and 2, the present flooring system is generally designated 10, and is used in a construction having a subfloor 12, shown schematically and typically poured concrete or at least one layer of plywood as is known in the art. While only the above two alternatives are disclosed, it is contemplated that any conventional subfloor material will be suitable for use with the present flooring system 10. As is known in the art, the subfloor is supported by joists (not shown) typically made of wood, steel or concrete.

The present flooring system 10 includes an acoustical isolation floor underlayment, generally designated 14 which is disposed between the subfloor 12 and a finished floor 16 which is typically ceramic tile, vinyl tile, hardwood or other hard materials other than carpeting. An adhesive layer 17 such as mortar, mastic or chemical adhesive secures the finished floor 16 to the underlayment 14.

A first layer 18 which is disposed upon the subfloor 12 is a sound reduction mat (SRM) made of a polymeric material and configured as a plurality of open hollow, cylinders 20 disposed in an array of spaced, preferably parallel rows with lower ends 22 facing the subfloor 12. The cylinders 20 are held together at opposite ends 24 by a polymeric lattice 26. Three functions are served by the SRM layer 18: it provides a water or vapor barrier, the cylinders 20 cushion the floor system 10 and absorb impact forces, and it provides one level of discontinuity of material and substantially reduced contact area, which is an important factor in reducing sound transmissions through the flooring system 10.

A preferred SRM is sold by USG under LEVELROCK™ SRM-25 sound reduction mat, having a polyethylene core forming the cylinders 22 and a polypropylene fabric forming the lattice 26. The lattice 26 also preferably has a textured upper surface 27 as shown fragmentarily in FIG. 1. While the above-described construction is considered preferred, it is also contemplated that other materials offering a cushioned vapor barrier and a discontinuous material may be used. One alternative providing less desirable acoustical properties is the above-described non-woven nylon fiber or coated wire matting such as ENKASONIC #9110 matting, manufactured by Coldbond Inc., Enka, N.C., used above a separate water impervious mat.

A second layer of the acoustical isolation underlayment 14 is generally designated 28 and is preferably a sheet of fibrous material of homogeneous thickness and construction. In the present application, “homogeneous” shall refer to the sheet having a substantially uniform height or thickness, and being substantially uniform across its area to provide consistent shock and sound absorption. Preferably, the second layer 28 is a sheet of fiberglass having a height or thickness of approximately ¼ inch and a density of approximately 3 pounds per cubic foot (pcf) (48.06 kg/cu.m). The second layer 28 is loosely disposed above the SRM 18, preferably without adhesive or other fasteners. Another important feature of the second layer 28 is that it is discontinuous with the SRM 18. As such, sound energy being transmitted through the floor system 10 is dampened and/or dissipated as it progresses through the layers 18, 28.

A third layer of the acoustical isolation underlayment 14 is generally designated 30 and is preferably a hi-density limp mass material with a high internal damping coefficient. In the present application, “high density” refers to densities in the preferred range of 22-72 pcf; however densities beginning at 10 pcf and exceeding 72 pcf are contemplated as being suitable. For the purposes of the present application, “high internal damping coefficient” refers to a coefficient of 0.01 or greater at 1000 Hz. Such material is discontinuous with the second layer 28. In addition, the material used in the layer 30 prevents compression of the fibrous second layer 28.

Preferably, the third layer 30 is provided as sheets of Sound Reduction Board having a composition of at least 30% by weight slag wool fiber; no more than 40% by weight expanded Perlite, less than 15% by weight starch, at least 5% by weight cellulose and, less than 10% by weight Kaolin and less than 5% by weight crystalline silica. The ingredients are mixed, formed into slurry, formed into sheets and dried. A suitable type of such SRB is sold by USG under the LEVELROCK™ SRB brand, however equivalent types of SRB are commercially available. The SRB 30 is preferably laid upon the second layer 28 without adhesive or fasteners.

Referring now to FIG. 3, an alternate sound reduction underlayment is generally designated 14a, and components shared with the underlayment 14 are designated with identical reference numbers. While it is preferred in the underlayment 14 that the fibrous layer 28 is below the SRB layer 30, in the underlayment 14a the disposition of these layers is reversed, with the SRB located directly above the SRM 18.

Referring now to FIG. 4, another alternate embodiment of the sound reduction underlayment 14 is generally designated 14b, and components shared with the underlayments 14, 14a are designated with identical reference numbers. In the underlayment 14b, an alternative material to the SRB in the third layer, designated 30′ is a cementitious or cement board such as DUROCK® brand cement underlayment board manufactured by USG. This board is formed pursuant to the process in U.S. Pat. No. 4,916,004, which is incorporated by reference. In summary, aggregated Portland Cement slurry is combined with polymer-coated glass fiber mesh encompassing front, back and edges.

As is the case with the SRB board, the DUROCK® brand cementitious board is preferably disposed above the fibrous layer 28, but it is also contemplated that the fibrous layer is located above the third layer 30′. It will also be understood that the DUROCK® brand cementitious board, when used as the third layer 30′, is acoustically discontinuous with the fibrous layer 28 and the SRM layer 18, as is the SRB.

In situations where the DUROCK® brand cement board is unsuitable, it is also contemplated that the third layer 30, 30′ may be provided in the form of a poured, settable high-density limp mass material having a high internal damping coefficient, such as DUROCK® brand formulation supplied by USG. An alternative material to DUROCK® material is FIBEROCK® brand aquatough fiber reinforced sheathing panels manufactured by USG.

To address the low profile requirement discussed above, it is preferred that the combined assembled height or thickness “T” of the layers 18, 28 and 30 or 30′ (FIG. 2) is less than or equal to one inch (2.5 cm). More specifically, the SRM 18 is preferably ¼ inch, the fibrous layer 28 is preferably ¼ inch, the SRB 30 is preferably ⅜ inch and the DUROCK® brand board 30′ is preferably ½ inch. While these are commonly available thicknesses for these materials, it is contemplated that other dimensions are suitable for specific layers depending on the application and provided the overall “T” thickness does not exceed one inch.

Once the acoustic isolation underlayment 14 is assembled upon the subfloor 12, in the preferred embodiment a poured layer of settable underlayment 32 is applied to an upper surface 34 of the third layer 30. In the preferred embodiment, the poured underlayment 32 is USG LEVELROCK™ floor underlayment 2500, having a composition of at least 85% by weight Plaster of Paris (CaSO4½H2O), less than 10% by weight Portland Cement and less than 5% by weight crystalline silica. Upon setting of the underlayment 32, the finished floor 16 is applied as is well known in the art. In practice, due to the tendency of the settable underlayment to migrate into the fibrous layer 28, the underlayment 14 is considered preferable in many applications to that of the underlayment 14a.

In the present preferred application, regarding the underlayment 14, the IIC values were determined using a full scale test per ASTM E497 and were found to meet or exceed stated requirements of 55-60 IIC.

In either formulation, having the highly damped limp mass material adjacent to the rigid dense underlayment helps to dampen the initial acoustical vibration and thus improves the overall performance of the floor system.

Referring now to FIG. 5, still another embodiment of the present floor system is generally designated 40. Components shared with the embodiments described above are designated with identical reference numbers. A layer of fibrous material 42, such as fiberglass as described above in relation to the layer 28, or other non-woven material is disposed upon the subfloor 12. As is the case with the layer 28, the fibrous material is homogeneous and is approximately ¼ inch high or thick. Next, the layer 42 is covered with a poured settable underlayment, 32 such as LEVELROCK™ underlayment discussed above. The finished floor 16 is then laid upon the LEVELROCK™ underlayment 32 as discussed above.

Thus, it will be seen that the present acoustical isolation underlayment system addresses the needs identified above, and provides a low profile system featuring several thin layers of discontinuous materials for absorbing sound energy between floors. Also, the structural integrity of the floor is maintained while also providing shock absorbing characteristics.

While particular embodiments of the present acoustical isolation floor underlayment system have been described herein, it will be appreciated by those skilled in the art that changes and modifications may be made thereto without departing from the invention in its broader aspects and as set forth in the following claims.

Claims

1. An acoustic isolation medium configured for placement between a subfloor and a finished floor with a poured underlayment, comprising: a first layer being a sound reduction mat disposed upon the subfloor;a second layer placed upon said first layer and being one of a sheet of fibrous material and a web of hi-density limp mass material with a high internal damping coefficient; anda third layer placed upon said second layer and being the other of a sheet of the fibrous material and a web of the hi-density limp mass material.

2. The isolation medium of claim 1 wherein said sound reduction mat comprises a plurality of hollow cylinders joined together at one end by a polymeric web.

3. The acoustic isolation medium of claim 2 wherein said hollow cylinders are arranged in a matrix of generally parallel rows held together by said polymeric web so that ends of the cylinders face the subfloor.

4. The isolation medium of claim 1 wherein said sheet of fibrous material is fiberglass.

5. The acoustic isolation medium of claim 4 wherein said fiberglass sheet is homogeneous.

6. The isolation medium of claim 1 wherein said sheet of fibrous material is approximately ¼ inch high and has a density of 3 pcf.

7. The isolation medium of claim 1 wherein said hi-density limp mass material with a high internal damping coefficient is taken from the group consisting essentially of sound reduction board and cementitious board.

8. The acoustic isolation medium of claim 1 wherein said three layers combined have a height of less than or equal to one inch.

9. The acoustic isolation medium of claim 1 wherein each of said first, second and third layers is made of a material which is acoustically discontinuous from adjacent layers.

10. The acoustic isolation medium of claim 1 wherein, upon installation with said underlayment poured above said medium forming a composite floor underlayment having an IIC at least in the range of 55-60.

11. An acoustic flooring isolation underlayment system configured for placement between a subfloor and a finished floor, comprising: a first layer being a sound reduction mat disposed upon the subfloor;a second layer placed upon said first layer, being made of a discontinuous material from said first layer, being homogeneous and providing cushioning and sound absorption; anda third layer placed upon said second layer, being made of a material which is discontinuous from said second layer, is homogeneous and is compression resistant.

12. The acoustic flooring system of claim 11 wherein said first, second and third layers have a combined height of less than or equal to one inch.

13. The acoustic flooring system of claim 11 further including a layer of poured settable material disposed upon said third layer.

14. The acoustic flooring system of claim 11 wherein said second and third layers are each a distinct one of a sheet of homogeneous fiberglass, a sound reduction board and a cementitious board.

15. An acoustic flooring system for use upon a subfloor and beneath a finished floor, comprising: a homogeneous sheet of fibrous material placed upon the subfloor; anda poured underlayment of settable material disposed directly upon said fibrous material.

16. The acoustic flooring system of claim 15 wherein said fibrous material is fiberglass with a 3 pcf density.