Abstract:
Building component assemblies include a sound-deadening board having defined compressional stiffness positioned between a framing member and an assembly board.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates generally to building materials and more particularly to materials used for sound insulation.  
           [0003]    2. Background Information  
           [0004]    In building modern structures, such as single-family houses or commercial buildings, an important factor to consider is noise control. In order to provide a quiet environment, sounds originating from sources such as televisions or conversation must be controlled and reduced to comfortable sound pressure levels. To achieve such an environment, builders and designers must address a multitude of factors, among them the construction and composition of building component assemblies that separate rooms from other rooms or from the outside environment. Such assemblies may, for example, take form as interior walls, exterior walls, ceilings, or floors of a building.  
           [0005]    The term “transmission loss” is expressed in decibels (db) and refers to the ratio of the sound energy striking an assembly to the sound energy transmitted through the assembly. A high transmission loss indicates that very little sound energy (relative to the striking sound energy) is being transmitted through an assembly. However, transmission loss varies depending on the frequency of the striking sound energy, i.e., low frequency sounds generally result in lesser transmission loss than high frequency sounds. In order to measure and compare the sound performances of different materials and assemblies (i.e., their abilities to block or absorb sound energy), while also taking into account the varying transmission losses associated with different sound frequencies, builders and designers typically use a single-number rating called Sound Transmission Class (STC), as described by the American Society For Testing and Materials (ASTM). This rating is calculated by measuring, in decibels, the transmission loss at several frequencies under controlled test conditions and then calculating the single-number rating from a prescribed method. When an actual constructed system is concerned (i.e., where conditions such as absorption and interior volume are not controlled in a laboratory environment), the single-number rating describing the acoustical performance of such a system can be expressed as a field STC rating (FSTC), which approximates a STC rating when tested on-site. The higher the FSTC rating of a constructed system, the greater the transmission loss.  
           [0006]    A conventional wall assembly  300  (called a wood stud wall) is shown in FIG. 3 and consists of two gypsum boards  303  (also referred to as drywall or sheetrock skins) attached directly to either sides of wood studs  301 . The space between the wood studs  301  may be filled with some type of fibrous insulation  305  (e.g., fiber glass batts). A wall assembly such as assembly  300  generally results in transmission loss values between STC  30  and STC  36 , because although the cavity area between the wood studs  301  is filled with sound insulation material  305 , sound energy can easily pass through the structural connections between the wood studs  301  and the gypsum boards  303 . Accordingly, assembly  300  is generally ineffective in reducing sound energy transmission.  
           [0007]    Several methods are currently used by builders to produce wall and ceiling/floor assemblies with higher FSTC ratings than the performance of a basic wood stud configuration. One such method is the use of resilient channels in a wall assembly  400 , shown in FIG. 4 a . This method involves inserting one or more thin metal channels  407  between one of the drywall skins  403  and framing members  401 . The resilient channels  407  act as shock absorbers, structural breaks, and leaf springs, reducing the transmission of vibrations between a drywall skin  403  and the framing members  401 . However, the resilient channel technique is difficult to install correctly and requires excessive labor costs. It is very easy to “short out” a resilient channel  407  by improper nailing techniques (e.g., screwing long screws into the wood studs  401  behind the resilient channel  407 ). When this occurs, the sound isolation of wall assembly  400  remains unimproved. Similarly, problems relating to the difficulty of installing resilient channels may result when the technique is used to sound-isolate floor-ceiling assemblies.  
           [0008]    Other current practices involve staggering the positions of wall studs  401  (as illustrated in FIG. 4 b ) or using double stud construction (as illustrated in FIG. 4 c ). These methods create a larger cavity depth and can reduce the structural connections between wall assembly components  401  and  403 , thereby allowing an assembly  400  to achieve relatively high FSTC ratings. However, both of these methods double the cost of framing and increase the thickness of wall assembly  400  by approximately two to four inches.  
           [0009]    In addition, various sound absorbing or barrier materials are currently used to provide a structural break between wall studs or floor-ceiling joists and the boards attached to them. Examples of such materials include GyProc® by Georgia-Pacific Gypsum Corporation, 440 Sound-A-Sote™ by Homasote and Temple-Inland SoundChoice™. While capable of providing additional sound-transmission loss, these materials are generally dense and heavy, resulting in high handling and installation costs.  
           [0010]    Accordingly, what is needed is a wall or floor-ceiling assembly that includes a material between the framing members and building boards either in sheets or strips that can provide additional substantial sound transmission loss, and is both relatively lightweight and easy to install.  
         SUMMARY OF THE INVENTION  
         [0011]    The present invention is directed to the installation of a lightweight sound-deadening board in sheets or strips in a wall or floor-ceiling assembly without the need for expensive methods, training, or tools. The lightweight board may be made of compressible material with an optimum range of compressibility. This material may be either non-resilient foam or a resilient non-foam material.  
           [0012]    According to a first embodiment of the present invention, a building component assembly is provided comprising at least one assembly framing member, at least one assembly board, and at least one sound-deadening board, wherein the sound-deadening board is made of a substantially non-resiliently compressible material with an optimized compressibility, is positioned between the at least one assembly framing member and the at least one assembly board, and has an Equivalent Young&#39;s Modulus (bulk modulus of elasticity) between 50 and 600 pounds per square inch and a thickness between ¼ and 1 inch. This value may be achieved through means of basic material properties (true Young&#39;s Modulus), or by the physical alteration of the board to make the modulus appear lower when installed in the described manner. Kerfing, grooving, waffle cuts and boring are all examples of such alterations.  
           [0013]    According to a second embodiment of the present invention, a building component assembly is provided comprising at least one assembly framing member, at least one assembly board, and at least one sound-deadening board, wherein the sound-deadening board is made of a substantially resiliently compressible non-foam material with an optimized compressibility, is positioned between the at least one assembly framing member and the at least one assembly board, and has an Equivalent Young&#39;s Modulus (bulk modulus of elasticity) between 50 and 600 pounds per square inch and a thickness between ¼ and 1 inch. This value may be achieved through means of basic material properties (true Young&#39;s Modulus), or by the physical alteration of the board to make the modulus appear lower when installed in the described manner. Kerfing, grooving, waffle cuts and boring are all examples of such alterations.  
           [0014]    According to a third embodiment of the present invention, a method of installing a sound-deadening board in building component assembly is provided, comprising the steps of attaching at least one sound-deadening board to at least one assembly framing member, and attaching at least one assembly board to the at least one assembly framing member and at least one sound-deadening board, such that the sound-deadening board is positioned between the assembly board and the assembly framing member, wherein the sound-deadening board is substantially made of a non-resiliently compressible material with an optimized compressibility, is positioned between the at least one assembly framing member and the at least one assembly board and has an Equivalent Young&#39;s Modulus (bulk modulus of elasticity) between 50 and 600 pounds per square inch and a thickness between ¼ and 1 inch. This value may be achieved through means of basic material properties (true Young&#39;s Modulus), or by the physical alteration of the board to make the modulus appear lower when installed in the described manner. Kerfing, grooving, waffle cuts and boring are all examples of such alterations.  
           [0015]    According to a fourth embodiment of the present invention, a method of installing a sound-deadening board in building component assembly is provided, comprising the steps of attaching at least one sound-deadening board to at least one assembly framing member, and attaching at least one assembly board to the at least one assembly framing member and at least one sound-deadening board, such that the sound-deadening board is positioned between the assembly board and the assembly framing member, wherein the sound-deadening board is substantially made of a resiliently compressible non-foam material with an optimized compressibility, is positioned between the at least one assembly framing member and the at least one assembly board and has an Equivalent Young&#39;s Modulus (bulk modulus of elasticity) between 50 and 600 pounds per square inch and a thickness between ¼ and 1 inch. This value may be achieved through means of basic material properties (true Young&#39;s Modulus), or by the physical alteration of the board to make the modulus appear lower when installed in the described manner. Kerfing, grooving, waffle cuts and boring are all examples of such alterations. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    Other objects and advantages of the present invention will become more apparant from the following detailed description of preferred embodiments, when read in conjunction with the accompanying drawings wherein like elements have been represented by like reference numerals and wherein:  
         [0017]    [0017]FIG. 1 illustrates a wall assembly built in accordance with the present invention;  
         [0018]    [0018]FIG. 2 illustrates a floor-ceiling assembly built in accordance with the present invention;  
         [0019]    [0019]FIG. 3 illustrates a conventional wall assembly; and  
         [0020]    [0020]FIG. 4 a - b  illustrate conventional methods of sound control in wall assemblies. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]    [0021]FIG. 1 shows a wall assembly  100  including wall studs  101  and wallboards  103  (also called leaves or skins). Studs  101  may be standard wall studs, made of either wood or metal (e.g., steel), and may be lightweight (25 gauge) or heavyweight (20, 18, or 16 gauge). Wallboards  103  may be one of several different varieties of structural skin, such as plasterboard, gypsum board, or plywood.  
         [0022]    Integrated into wall assembly  100  and positioned between each stud  101  and wallboard  103  is a sound-deadening board  109  made of either non-resiliently compressible material or resiliently compressible non-foam material. Boards  109  may also be positioned on both sides of studs  101  (not shown). Boards  109  reduce vibration transfer between a wallboard  103  and the studs  101 , resulting in enhanced sound isolation between rooms located on either side of assembly  100 . Analytical modeling and laboratory testing has shown that optimum sound control performance results when board  109  has an Equivalent Young&#39;s Modulus (bulk modulus of elasticity) between 50 and 600 pounds per square inch, a value much lower than the stiffness values associated with conventional materials used in building wall or floor-ceiling assemblies (e.g., gypsum boards and wood studs). These optimum sound control results were found where the sound-deadening board  109  thickness was between ¼ and 1 inch. Modeling and testing also showed that materials with an Equivalent Young&#39;s Modulus (bulk modulus of elasticity) between 50 and 500 pounds per square inch, were found to offer broadband improvements with a maximum of 6 to 8 dB improvement at the 1600 Hz one-third octave band. More specifically, materials with an equivalent Young&#39;s Modulus (bulk modulus of elasticity between 500 to 600 pounds per square inch, were found to offer broadband improvements with a maximum of 3 to 4 dB improvement at the 1600 Hz one-third octave band. Therefore, materials with Young&#39;s Moduli within the described range offer the best sound control performance, while materials with higher Young&#39;s Moduli offer some improvement in terms of sound transmission loss.  
         [0023]    Existing materials that possess Young&#39;s Modulus values less than those of conventional wall or floor-ceiling assembly materials are not currently being used in sound-control applications. An example of an existing material that may be used as board  109 , and is non-resiliently compressible, is isocyanurate foam sheathing (also called “iso foam”), which is currently used only for thermally insulating exterior walls and not for sound-deadening interior wall or floor-ceiling assemblies. Another candidate non-resiliently compressional material is blue closed cell sill seal foam, also not normally used for sound-deadening interior wall or floor-ceiling assemblies. EPDM rubber is an example of an existing resiliently compressible non-foam material that may be used as board  109  which is not presently installed for sound control purposes. Of course, any material with an Equivalent Young&#39;s Modulus less than the Young&#39;s Moduli of conventional wall or floor-ceiling assembly materials may be used in the present invention. As described above, however, an optimal range of sound control performance results when the material has an equivalent Young&#39;s Modulus (bulk modulus of elasticity) between 50 and 600 pounds per square inch and a thickness between ¼ and 1 inch.  
         [0024]    Board  109  preferably has a thickness of between ¼ and 1 inch and approximately 0.125 to 1 inch and may be manufactured from a wide variety of materials, including, but not limited to, a cellulosic fiber material (e.g., recycled newsprint), perlite, fiber glass, or latex. Board  109  also is preferably manufactured to a density of 1 to 14 pounds per cubic foot, which is less than the density of current sound-control boards. For example, 440 Sound-A-Sote™ has a density of 26 to 28 pounds per cubic foot and Temple-Inland SoundChoice™ has a density of 15 to 20 pounds per cubic foot. Board  109  therefore is much lighter and less stiff than current sound-control boards, resulting in greater ease of handling and lower installation costs. Testing has shown that the installation of a sound-deadening board as described above between the skins and studs of a wall assembly can yield STC ratings of 41 or higher. In contrast, an unimproved wall assembly, as mentioned before, has a maximum STC rating of about 36.  
         [0025]    [0025]FIG. 2 shows another application of sound-deadening boards meeting the above-described requirements (e.g., the requirements for, Young&#39;s Modulus, thickness, and density). In a floor-ceiling assembly  200 , boards  209  are positioned between joists  201  and floor layers  203 , while boards  211  are positioned between the other sides of joists  201  and ceiling layers  203 . Boards  209  and boards  211  may both be made of the same material, or may be made of two different materials, each meeting the above-described requirements. Of course, assembly  200  may include only one of the two boards  209  and  211 , or may include both as shown. STC ratings of approximately 50 may be achieved in such a configuration as floor-ceiling assembly  200 .  
         [0026]    The installation of boards  109  (as well as boards  209  and  211 ) is simple and does not require careful installation or expert workmanship. An installer may use conventional gas or fluid-powered automatic fasteners to quickly attach the lightweight board to wall studs or floor-ceiling joists. The installer then covers and attaches a layer of structural skin, such as gypsum board, to the studs or joists through the board. The lightweight board may or may not be attached to both sides of a stud or joist.  
         [0027]    Boards  109  and  209  are shown respectively in FIGS. 1 and 2 as preferably having widths approximately equal to the edge widths of studs  1021  and joists  201 . As an alternative, boards  109  and  209  may, of course, have widths greater than the edge widths of studs  101  and joists  201  and may span from one stud  101  or joist  201  to another. However, testing has shown that it is only essential to separate wallboards from studs (and floor sheets from joists) using sound-deadening material of a width approximately equal to the edge width of the studs (or joists).  
         [0028]    A wall or floor-ceiling assembly with an integrated sound-deadening board in accordance with the present invention provides excellent acoustical performance while being the lowest-cost system in terms of both materials and labor cost. This advantage is due to the simplicity of installation, which also establishes high confidence that a wall or floor-ceiling assembly installed with the sound-deadening board possessing the above-described characteristics may also provide some type of thermal benefit (e.g., as with iso foam sheathing) and/or moisture control.  
         [0029]    It will be appreciated by those skilled in the art that the present invention can be embodied in other specific form without department from the spirit or essential characteristics thereof. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restricted. The scope of the invention is indicated by the appended claims rather than the foregoing description and all changes that come within the meaning and range and equivalence thereof are intended to be embraced therein.