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CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 61/545,998, filed Oct. 11, 2011, which is hereby incorporated by reference. 
     
    
     FIELD 
       [0002]    The present disclosure concerns embodiments of a construction technique that can be used for modifying existing walls. 
       BACKGROUND 
       [0003]    There are many structures in need of structural reinforcement or retrofitting to provide better insulation, waterproofing, a vapor barrier, and/or aesthetic properties. In some cases these are older structures whose designs or methods of construction are inadequate in light of present engineering standards and construction methods. In other cases these are new structures under construction that could benefit from the development of new methods of reinforcing and otherwise modifying existing designs. 
         [0004]    Accordingly, it would be desirable to provide methods of modifying these walls in ways that provide greater strength, insulation, waterproofing, vapor-proofing, or aesthetics. One method of reinforcing such walls is disclosed in U.S. Pat. No. 6,662,516 B2, which describes a method of filling a double wall structure and methods of reinforcing a single wall structure with a foamable, adhesive material. Some of the methods described therein require the use of studs and in some cases the use of mechanical fasteners to secure the reinforcing materials to the existing wall. The use of studs in such methods can create thermal pathways which lead to energy losses through the wall and represent an additional cost. Similarly, the use of mechanical fasteners represents an additional cost and may create perforations in the reinforcing material, decreasing its insulation and waterproofing qualities. Thus, methods of modifying existing walls to provide a traditional wall surface without the use of studs or mechanical fasteners would be desirable. 
       SUMMARY 
       [0005]    Disclosed herein are embodiments of an invention allowing the modification of existing walls. The disclosed methods can be applied to a wall of an old house or building or to a recently constructed existing wall of a house or building under construction. In some embodiments, a form assembly is provided with a form member facing an existing wall, to which sheathing panels are attached. The cavity created between the sheathing panels and the existing wall can be filled with a foamable, adhesive material which adheres to the sheathing panels and the existing wall and creates an adhesive connection between them. In some embodiments, the form assembly is vertically adjustable to facilitate the installation of multiple rows of sheathing panels. In some embodiments, the foamable, adhesive material is introduced in successive layers. 
         [0006]    In one embodiment, a temporary form member can be positioned such that its inner surface is separated from and faces an existing wall. A sheathing panel can be temporarily secured to the form member and the cavity between the sheathing panel and the existing wall can be filled with a foamable, adhesive material which is allowed to cure. Thereafter, the temporary form member can be removed from the sheathing panel. 
         [0007]    In another embodiment, a plurality of vertical posts can be positioned in a row along an existing wall. A vertically adjustable form member can be coupled to the vertical posts such that an inner surface of the form member is separated from and faces the existing wall. A sheathing panel can be temporarily secured to the inner surface of the form member and the cavity between the sheathing panel and the existing wall can be filled with a foamable, adhesive material which is allowed to cure. Thereafter, the temporary form member can be removed from the sheathing panel. 
         [0008]    In yet another embodiment, a plurality of vertical posts can be spaced apart from each other in a row along the length of an existing wall. Vertical sliding members can be adjustably coupled to the vertical posts and upper and lower adjustable frame arms can be connected to the top and bottom, respectively, of the vertical sliding members. Thereafter, a form member can be connected to the upper and lower adjustable frame arms such that it is separated from and faces the existing wall. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIGS. 1 and 2  illustrate a method for securing a sheathing layer to an existing wall, according to one embodiment. 
           [0010]      FIGS. 3 and 4  are front elevation and top plan views, respectively, of a completed wall structure comprising a sheathing layer mounted to the interior surface of an existing wall. 
           [0011]      FIG. 5  illustrates from a top plan view a system for modifying an existing wall. 
           [0012]      FIG. 5A  illustrates from a side view a system for modifying an existing wall. 
           [0013]      FIGS. 6 and 7  illustrate a method of securing a sheathing layer to an existing wall, according to one embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]      FIGS. 1-2  and  5 - 5 A illustrate a method for securing a sheathing layer  8  to an existing wall  10 . In particular embodiments, the sheathing layer  8  is secured to the wall  10  without any studs positioned in the cavity C between the sheathing layer and the wall. The method involves the use of a foamable, adhesive material to secure the sheathing layer to the wall. The foamable, adhesive material also serves as a vapor barrier and a waterproofing layer for the wall structure, and insulates the structure. The sheathing layer also provides a suitable wall surface to which various finishes can be applied (e.g., paint, texturing materials). The method has particular applicability for waterproofing a concrete wall or a masonry wall constructed from courses of masonry units (e.g., bricks, stones, concrete blocks, concrete masonry units, etc.), but can be used to modify a wall of any material. The existing wall can be a wall of an old structure (e.g., house or building) being renovated, or a recently built wall of a new structure being built. As such, the disclosed methods can be used for constructing new wall structures or for retrofitting existing wall structures. 
         [0015]    The sheathing layer  8  can be formed from any of various known materials, such as plywood, gypsum board (drywall), composition board, OSB, hardy board, metal siding, or other forms of boarding known in the art. In particular embodiments, the sheathing layer is formed from standard sections, or panels  14  of gypsum board, which typically are manufactured and sold in 4 foot×8 foot panels, 4 foot×9 foot panels, 4 foot×10 foot panels, or 4×12 foot panels. Gypsum board is desirable because it provides a fire-resistant layer over the adhesive material that is used to secure the sheathing layer to the wall  10  and because gypsum board provides a suitable wall surface that can be finished with any of various decorative materials, such as paint, wall paper, etc. In the illustrated embodiment, the sheathing layer is installed on the interior surface of the existing wall  10 . In other embodiments, a sheathing layer can be installed on the exterior surface and/or the interior surface of the existing wall. 
         [0016]    Referring again to  FIGS. 1-2  and  5 - 5 A, the individual panels  14  of the sheathing layer  8  can be installed using a slip form assembly  12 , which is configured to retain individual panels  14  in a vertical position spaced from the wall  10  such that a cavity C is formed between the sheathing panels  14  and the interior surface of the wall  10 . In various embodiments, the width of this cavity is at about 2 inches, but can vary depending upon the particular application. In use, the slip form assembly  12  contacts the outer surface of a sheathing panel  14  being installed and provides resistance against the force exerted on the inner surface of the panel by the foamable material injected into the cavity C. 
         [0017]    As illustrated in  FIG. 5 , the slip form assembly  12  can comprise a plurality of vertical posts  16  that are spaced horizontally from each other along a straight line spaced apart from the interior of the wall  10 . Each post  16  can extend the height of the room and can be secured at its lower end to the floor  18  and at its upper end to the ceiling  20 . Any of various suitable fasteners (e.g., nails, screws, etc.) can be used to temporarily secure the posts in place relative to the floor and the ceiling. For relatively tall walls (e.g., walls that are about 30 feet or greater in height between the floor and the ceiling), the posts can be reinforced with temporary wire ties or struts that secure the posts to the existing wall  10 . 
         [0018]    As illustrated in  FIG. 5 , a pair of support posts  16  can be provided for every sheathing panel  14 . Mounted to each pair of vertical posts  16  is a movable slip form frame  22 , which includes a respective vertical sliding member  17  on each post  16 , a vertically disposed form member  24 , a form frame  21 , a pair of upper frame arms  13  and a pair of lower frame arms  15 . Each vertical sliding member  17  is configured to slide vertically along a vertical post  16 , and is connected at its upper end to an upper frame arm  13 , and at its lower end to a lower frame arm  15 . The upper and lower frame arms are connected to a respective form frame  21 , which is connected to a vertically disposed form member  24 . In this configuration, the form member  24  is rigidly supported by and vertically movable with the vertical sliding members  17 , which are in turn supported on a pair of vertical posts  16 .  FIG. 1  shows the slip form frame  22  in its lowermost position and configured for the installation of the lowermost row  9   a  of panels  14 . The slip form frame  22  can be raised vertically relative to the support posts  16  as the rows of panels  14  are installed one on top of another, as illustrated in  FIG. 2 , and as further described below. 
         [0019]    Each sheathing panel  14  can be a conventional 4 foot×12 foot piece of drywall, and each form member  24  can have an overall size (length and height) that is about the same as the size of the panels  14 . For example, when installing 4 foot×12 foot panels, the form member  24  can have a height of about 4 feet and a length of about 12 feet. In the embodiment illustrated in  FIG. 5 , each sheathing panel  14  and corresponding form member  24  is 12 feet wide, and each form frame  21  is 11 feet 10 inches wide, leaving two inches of clearance between neighboring form frames  21 . As illustrated, for a 12-foot sheathing panel  14 , the paired support posts  16  can be spaced 6 feet 8 inches apart, leaving 5 feet 4 inches separating posts of adjacent pairs. 
         [0020]    In  FIGS. 1-2 , the form member  24  is connected directly to the pair of upper frame arms  13  and the pair of lower frame arms  15 . Alternatively, the form member  24  can be supported on a form frame  21 , which is in turn supported by the pair of upper frame arms  13  and the pair of lower frame arms  15 , as illustrated in  FIGS. 5-5A . The form frame  21  can comprise an upper, horizontally disposed elongate tubular member  60  extending between a pair of upper frame arms  13 , and a lower, horizontally disposed elongate tubular member  62  extending between a pair of lower frame arms  15 , each extending horizontally along the length of the wall  10 . The form frame can further comprise a plurality of vertically disposed tubular members  64  extending between the upper tubular member  60  and the lower tubular member  62 , and spaced apart from each other at regular intervals. In this configuration, the form frame resembles a ladder extending along and facing the wall, with the vertical tubular members  64  representing rungs of the ladder. Use of the intermediate form frame  21  can be advantageous to increase the rigidity of the form member  24  in cases where the form member  24  comprises a relatively flexible material, e.g., plywood. 
         [0021]    In some embodiments, the upper and lower frame arms are configured to permit adjustment of the position of the form member  24  relative to the wall  10  and therefore the size of the cavity. For example, as illustrated in  FIG. 5A , the upper frame arm  13  can comprise a first plate  70  connected to the upper end of the vertical sliding member  17  and a second plate  78  connected to the upper end of the form frame  21 . A first angle iron, or bracket,  72  can be bolted or otherwise secured to the first plate  70  and a second angle iron, or bracket,  76  can be bolted or otherwise secured to the second plate  78 . A threaded rod  74  can be welded to the first and second angle irons, thereby completing the upper arm  13 . In some embodiments the upper frame arm may also be provided with a turnbuckle  80  connecting two sections of the threaded rod  74  for adjusting the length of the upper frame arm  13 , in which case the two sections of threaded rod can be threaded into brackets  72  and  76 . In some embodiments, the lower frame arm  15  comprises a first slotted tube  82  having an outside diameter slightly smaller than the inside diameter of a second slotted tube  84  so that the first slotted tube  82  can be inserted into the second tube in a telescoping manner. By inserting the first slotted tube into the second so that their slots align and sliding one slotted tube with respect to the other, the length of the lower frame arm  15  may be adjusted. By providing a bolt  86  through the slots in both tubes and tightening it with a wingnut  88 , the lower frame arm  15  may be secured and may be provided with strength sufficient to be walked on. The first slotted tube  82  may be connected to the form frame  21  and the second slotted tube may be connected to the vertical sliding member  17  by any suitable techniques or mechanisms, such as bolts, welding, etc. In this configuration, the adjustable nature of the upper and lower frame arms allows rapid changes in the width of the cavity and provides a simple method for achieving proper orientation of the sheathing panels during construction. 
         [0022]    Because the foil member  24  comes in direct contact with the sheathing layer, the form member  24  desirably has a surface that minimizes sliding friction with the outer surface of the sheathing layer when the form member is raised to a higher elevation for installing the next row of panels  14 . For example, the form member  24  can comprise a metal or metal clad form, or a base layer (e.g., metal) having a low friction polymeric layer or coating made of PTFE (polytetrafluoroethylene) or HDPE (high-density polyethylene). The low friction surface allows the form member  24  to slide upwardly relative to a panel  14  of the sheathing layer after it has been installed. 
         [0023]    The form assembly  12  can be provided with releasable securement devices that secure the frame  22  at selected positions along the height of the support posts  16  for installing each row of panels  14 . The securement devices can be, for example, removable pins that extend into openings in the support posts  16  and corresponding openings in the sliding frame  22 . 
         [0024]    A plurality of slip form assemblies  12  can be provided, on which plural form members  24  can be mounted end-to-end such that a form extends along the entire length of the wall  10 . In this configuration, a row of panels  14  extending the entire length of the wall  10  can be positioned adjacent the wall  10  at the same time and secured in place with continuous layers of adhesive material extending the length of the wall in the cavity C. After each row of panels is formed, the frames  22  and respective form members  24  are raised to install the next row of panels  14  above the previously formed row of panels. 
         [0025]    In certain applications, such as when installing a sheathing layer on a relatively long wall, the frames  22  and form members  24  need not extend the entire length of the wall. In such cases, a complete row of panels  14  extending the length of the wall can be installed in sections that extend less than the length of the wall. When forming a partial row of panels, the exposed end of the cavity C can be covered with a layer of material to retain the adhesive material in the cavity. 
         [0026]    Prior to placing the lowermost row of panels  14  on the slip form assembly  12 , a starter clip  26  can be secured to the floor at the location where the lowermost row of panels  14  is to be installed. The clip  26  can be an L-shaped bracket or angle bracket that extends the entire length of the wall or at least partially along the length of the wall at the intersection of the floor and the lower edges of the panels  14 . The clip  26  helps prevent the panels from sliding inwardly toward the wall. As shown in  FIG. 1 , the upper edge of the panel  14  can be temporarily secured to the upper edge of the form  24 , such as with one or more spring clips or clamps  28  spaced along the upper edge of the form  24 . As shown in  FIG. 3 , one or more conventional ply clips  38  can be used to help align the adjacent vertical edges of adjacent panels  14  in the same row. A layer of tape  50  can be applied to the adjacent vertical edge portions of the panels  14  on their inner surface (inside the cavity) to help seal the abutting edges of the panels and prevent or at least minimize foam leaks. A roller device  52  can be used to apply the tape to the inner surface of the panels (inside the cavity). Alternatively, the tape  50  can be applied to the outer surface of the sheathing layer. At the corner of the sheathing layer, the vertical edges of the panels  14  can be secured to a vertical angle bracket  54 . 
         [0027]    After the lowermost row  9   a  of panels  14  is in place to form the cavity C, the cavity can be filled with the foamable, adhesive material  30  to bond the panels  14  to the existing wall  10 . In particular embodiments, the cavity is filled with a plurality of layers  32  of the foamable, adhesive material  30 . Desirably, the adhesive material  30  has the following characteristics: high adhesion to provide a strong bond between the walls; high compressive, tensile, and shear strength; and low expansion. The adhesive material  30  desirably is sufficiently elastic to adsorb energy transmitted to the wall structure caused by seismic activity, has a minimal set up or cure time, and produces minimal off gases harmful to those handling the adhesive material. The adhesive material  30  also may be selected to provide waterproofing for the wall structure to which the adhesive material is applied. Some examples of adhesive material that can be used include, without limitation, open or closed cell polyurethane foam, or other suitable materials. Closed cell foams are most desirable in that they are substantially impervious to water. A suitable polyurethane foam is SR Foam, a closed cell polyurethane foam available from SR Contractors (Portland, Oreg.). The adhesive material  30  desirably has a density from about 1 lb./ft. 3  to 10 lbs./ft. 3 , and even more desirably from about 2 lbs./ft. 3  to 10 lbs./ft. 3    
         [0028]    The adhesive material can be formed by mixing a resin base material stored in a first container with a conventional activating agent stored in a second container. In one example, the base material and activating agent are mixed in a one-to-one ratio. To form polyurethane foam, such as described above, the base material would be a polyurethane resin. The base material may contain surfactants, fire retardants, a blowing agent and other additives. The density of the adhesive material  30  introduced into the cavity can be varied by starting with a base material of a different formulation, typically by varying the amount of activating agent in the formulation. 
         [0029]    Pumps (not shown) in the first and second containers pump the resin base material and activating agent, respectively, through respective hoses (not shown) into a proportioning unit (not shown). The proportioning unit pumps the base material and the activating agent at about 1000 psi through respective hoses  34  to a spray gun, or nozzle,  36  wherein the base material is mixed with the activating agent. The proportioning unit and the hoses desirably have heating coils to preheat the base material and activating agent to about 120 degrees F. When the materials mix in the spray gun  36 , the activating agent triggers an exothermic chemical reaction, the product of which is the adhesive foam material  30  typically having an initial temperature of about 140 degrees F. During this early exothermic stage, the foam is in a viscous seam-like state and can be poured into the cavity. Once in the cavity the foam flows and expands to fill the cavity. The slip form assembly  12  holds the panels  14  in place against the force exerted by the expanding foam. 
         [0030]    The nozzle  36  is moved longitudinally along the bottom of the cavity to form an even layer  32  of material of a height H. After the adhesive material is sprayed into the cavity to form the bottommost layer  32 , the end of the nozzle  36  is raised a sufficient distance so as to avoid contact with the expanding adhesive material, which is allowed to cure before another layer of adhesive material is formed on the bottommost layer  32 . Preferably, the adhesive material is cured until it expands at only a minimal rate (e.g., the adhesive material has expanded to about 99 percent of its expanded state), or more even preferably, to a point where the adhesive material no longer expands. The cure time is a function of the foam density. For example, the cure time for a foam density of 2 lbs./ft. 3  is about 4 minutes while the cure time for a foam density of 10 lbs./ft. 3  may be longer. Once the adhesive material has substantially cured, the end of the nozzle  36  is positioned at a point just above the previously formed, bottommost layer  32  and adhesive material is sprayed on top of the bottommost layer as the nozzle is moved longitudinally along the cavity so as to form an additional layer of adhesive material. The layering process is then repeated until the cavity is filled with layers having substantially the same height H (as illustrated in  FIG. 1 ). In particular embodiments, the height H of each layer  32  is about 6 inches to about 48 inches, with about 12 inches being a specific example. Additional details regarding the foamable material  30  and the technique for forming successive layers in the cavity are provided in U.S. Pat. No. 6,662,516, which is incorporated herein by reference. 
         [0031]    After filling the cavity and allowing the adhesive material to cure, another row  9   b  of panels  14  can be installed above the previously installed row  9   a  of panels. To install the next row of panels, the clips  28  are removed from the form  24 , and the frame  22  and the form member  24  are raised to a new position above the previously installed row  9   a , as depicted in  FIG. 2 . The panels  14  of row  9   b  are positioned such that their lower longitudinal edges abut the upper edges of the panels below. As best shown in  FIG. 3 , one or more conventional ply clips  38  can be placed along the upper edges of the lower panels and the lower edges of the upper panels to assist in aligning the panels of the adjacent rows. The abutting longitudinal edge portions of the panels can be covered with a layer of tape  50  (which can be placed on either the inner or the outer surface of the panels). After a cavity is formed between the row  9   b  of the panels and the wall  10 , the cavity can be filled with the adhesive material  30 , in the manner described above. The process of raising the frame  22  and the form  24 , installing a new row of panels, and filling the cavity with the adhesive material  30  can be repeated as needed until the uppermost panel is installed. 
         [0032]    When installing the uppermost row of panels adjacent the ceiling  20 , an upper angle bracket  40  can be secured to the ceiling to assist in supporting the upper edges of the panels  14  in the uppermost row (see  FIG. 2 ). In order to inject the foamable material  30  into the cavity, a series of small holes  42 , large enough to receive the distal end portion  44  of the nozzle, can be formed along the upper edge portion of the panel  14 . The distal end portion  44  of the nozzle  36  can be inserted into the various holes  42  for forming layers  32  of adhesive material  30  filling up the cavity C between the wall  10  and the uppermost row of panels  14 . 
         [0033]    Advantageously, the adhesive material  30  secures the panels of the sheathing layer to the wall  10  without any studs or mechanical fasteners, such as nails or screws. The layers of material  30  also function as a water and air barrier for the wall structure such that traditional wall waterproofing is not required. The adhesive material  30  also insulates the wall structure and further reduces energy losses by eliminating the thermal transfer pathways of furring studs. After the sheathing layer is installed, the slip form assembly  12  can be converted into a movable platform  19  for use in finishing the outer surface of the sheathing layer (e.g., painting the sheathing layer). For example, the frame  22  and the form  24  can be placed in a horizontal position to allow a worker to sit or stand on the form  24  when applying a finish to the sheathing layer. Further, in some embodiments, the seams where sheathing panels  14  meet may be sealed with a sealant  11 , such as an epoxy or a polyurethane foam, with one specific example being the Hilti CF 812 Window and Door Low-Pressure Filler Foam. The sealant  11  between panels  14  may be applied to vertical seams within rows of sheathing panels  14 , as well as horizontal seams between rows. Thereafter, the slip form assembly  12  can be removed. 
         [0034]      FIGS. 3 and 4  are front elevation and top plan views, respectively, of a completed wall structure comprising a sheathing layer  8  mounted to the interior surface of the wall  10 . As shown in  FIG. 3 , the sheathing layer  8  comprises a plurality of rows  9   a ,  9   b , etc. of panels  14  extending the length of the wall  10 . Of course, the number of rows of panels will depend on the height of the wall  10  and the dimensions of the sheathing panels  14 . 
         [0035]      FIGS. 6 and 7  illustrate a method for securing a sheathing layer  8  to an existing wall  10 , using a frame assembly  12 ′ of a different construction. As illustrated, the frame assembly  12 ′ comprises a slip form frame  100  having a vertical sliding member  102 , three connecting members  104 , and a form member  24 . The vertical sliding member  102  is mounted to one or more vertical posts  16  for vertical movement (upwardly and downwardly) relative to support posts  16 . The three connecting members  104  are each attached to the sliding member  102  at one end and to the form member  24  at the other. This arrangement rigidly connects the form member  24  to the sliding member  102  and allows the form member  24  to be adjusted up and down as the sliding member  102  moves along the support posts  16 .  FIG. 6  shows the slip form frame  100  in its lowermost position, for installation of the lowermost row  9   a  of sheathing panels  14 . The slip form frame  100  can be raised vertically relative to the support posts  16  to install another row  9   b  of sheathing panels  14 , as shown in  FIG. 7 . 
         [0036]    In view of the many possible embodiments to which the principles of the disclosed invention may be applied, it should be recognized that the illustrated embodiments are only preferred examples of the invention and should not be taken as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims. I therefore claim as my invention all that comes within the scope and spirit of these claims.

Summary:
Systems and methods for modifying existing walls are disclosed. In some embodiments, a form assembly is provided with a form member facing an existing wall, to which sheathing panels are attached. The cavity created between the sheathing panels and the existing wall can be filled with a foamable, adhesive material which adheres to the sheathing panels and the existing wall and creates an adhesive connection between them. In some embodiments, the form assembly is vertically adjustable to facilitate the installation of multiple rows of sheathing panels. In some embodiments, the foamable, adhesive material is introduced in successive layers.