Abstract:
A wall repair and construction method and structure using foam, such as expanding foam, to fill large gaps and holes, and then top coating with plaster. The foam provides a strong, rapidly-cured support structure, and the plaster provides an attractive finish surface. Thus, holes can be repaired in substantially less time than conventionally, and maintain substantial strength. Additionally, construction of walls can be performed rapidly.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates generally to construction and repair of walls and ceilings, and more particularly to a method of repairing and constructing wall and ceiling panels, and the apparatus resulting from the repair and construction. 
         [0003]    2. Description of the Related Art 
         [0004]    It is known in the prior art to construct walls and ceilings of buildings from sheet stock, commonly referred to as drywall and sold under the trademark SHEETROCK, among others. Such drywall sheet stock is made of fiber-reinforced gypsum sandwiched between sheets of paper. Conventional construction methods include nailing, screwing and/or gluing the sheets of drywall to frame members, such as wood or metal “studs”, rafters and beams that form the building&#39;s structural support. Subsequently, a paste plaster, commonly referred to as “mud”, is troweled into any cavities in the wall such as grooves formed between sheets and circular cavities formed where screws or nails have been driven into the sheets. Typically, paper or fiber tape is embedded in the plaster over any long grooves between adjacent sheets, in order to reduce or eliminate reflective cracking through the grooves. The plaster forms the finished surface of the wall once it is sanded after curing and hardening. 
         [0005]    Repairing holes or joints in installed drywall is difficult for several reasons. The normal manner of repairing drywall is to plaster over a small crack or hole. However, for larger holes that cannot support plaster alone, one commonly inserts into the hole a piece of drywall that is slightly smaller than the hole, and then plasters over the seams that remain. Alternatively, one can cut away drywall to expose the beams or studs so that the drywall piece can be attached thereto for support. However, such a repair is more susceptible to subsequent damage than the original wall, and the repair process is very time-consuming, because it requires thick layers of plaster that are used to patch the seams or gaps to cure or dry. Thicker layers of plaster typically shrink, and this requires subsequent layers of plaster to be applied, which results in more time drying. 
         [0006]    During a normal drywall repair, it is difficult to access the regions of a wall that support the drywall sheet without removing a significant amount of the drywall that surrounds the hole in order to find a support member, such as a stud. By increasing the size of the hole, the typical repair partially negates the principle of repairing the wall. Additionally, even if one or more studs can be accessed, attaching a small sheet of drywall to the studs does not result in the repair being as strong as the original drywall. This is because drywall can only be plastered at the seams on the outwardly facing side, not the opposite side. Thus, a small force is necessary to fracture the repaired seam. During original construction, seams are placed over support members to the extent possible, so that it is inconsequential that the original seams are only plastered on the face. In repair, however, it is rarely possible to place seams entirely over studs. 
         [0007]    In addition to the decreased strength of repaired drywall walls, the repair of drywall typically takes a substantial amount of time. This is due to the fact that most drywall repairs require a thick layer of plaster at least over some regions of the repair. Plaster takes a substantial amount of time to cure or dry, and the thicker the layer, the longer it takes to harden. The shrinking of thicker coats of plaster requires a second, thinner coat to cover any cracks or gaps formed by shrinking. This requires even more time until a finished surface is formed. 
         [0008]    Therefore, the need exists for a sheet wall repair and construction method and apparatus that reduce or eliminate the weakness inherent in conventional repaired sheet wall products, and can be carried out in less time. 
       BRIEF SUMMARY OF THE INVENTION 
       [0009]    The invention provides a method of constructing a finished wall with a continuous planar face. The method comprises joining at least two sheets of wall material to at least one wall support member. This thereby forms a void at the junction of the two sheets. A foam material is applied in the void, and the foam material occupies a significant portion of the void. A curing plaster paste is applied over the foam material and adheres to the foam material. When cured, the plaster forms a continuous finished planar face with the sheets. 
         [0010]    The invention also contemplates a finished wall with a continuous planar face. The wall comprises two sheets of wall material joined to a wall support member, in which the junction of the sheets forms a void. A foam material is mounted in the void, and the foam material occupies a significant portion of the void, for example to conform to any irregularities in the wall so that the irregularities can be corrected during finishing. A plaster layer is mounted over and adhered to the foam material to form a continuous finished planar face with the sheets. 
         [0011]    A method of constructing a finished wall with a continuous planar face is further contemplated. The wall includes a first sheet and a second, substantially parallel, sheet. The first and second sheets are separated to form a gap in which at least wall support members, such as studs, are interposed and attached to the first and second sheets. The method comprises a step of inserting a fluent material in the gap through a void formed through the first sheet. The void is typically a hole that is to be repaired. The material expands to form a foam extending from attachment at the second sheet to attachment at the first sheet at the void. Additionally, a curing plaster paste is applied over the foam and adheres to the foam material. The plaster forms a continuous finished planar face with the sheets. 
         [0012]    Using the method, and constructing the structure, results in an improved finished wall surface. One method is particularly advantageous when repairing a hole in a drywall wall, and another method is particularly advantageous when constructing a new wall. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0013]      FIG. 1  is a front view illustrating a wall with a hole formed therein. 
           [0014]      FIG. 2  is a front view illustrating the wall of  FIG. 1  with an expanded foam injected in the hole and protruding therefrom. 
           [0015]      FIG. 3  is a top view illustrating a chamber between two wall sheets, one of which is the wall sheet of  FIG. 1 , as separated by two pieces of dimensional lumber, and a foam support extending between the two wall sheets. 
           [0016]      FIG. 4  is a front view illustrating the wall of  FIG. 2  with the expanded foam cured and cut back to substantially flush with the wall. 
           [0017]      FIG. 5  is a front view illustrating the wall of  FIG. 4  with a small amount of paste plaster adhered over part of the cured foam. 
           [0018]      FIG. 6  is a front view illustrating the wall of  FIG. 5  with the paste plaster spread over the cured foam to form a finished surface. 
           [0019]      FIG. 7  is a front view illustrating an alternative embodiment of the invention with a mesh basket inserted in a hole in a wall. 
           [0020]      FIG. 8  is a top view illustrating the wall of  FIG. 7  with a chamber between two wall sheets, one of which is the wall sheet of  FIG. 7 , as separated by two pieces of dimensional lumber, and the mesh basket extending between the two wall sheets. 
           [0021]      FIG. 9  is a front view illustrating the wall of  FIG. 7  with an expanded foam injected in the hole. 
           [0022]      FIG. 10  is a top view illustrating the chamber of  FIG. 8 , and a foam support infiltrating the mesh basket and extending between the two wall sheets. 
           [0023]      FIG. 11  is a front view illustrating the wall of  FIG. 7  with the expanded foam cured and cut back to substantially flush with the wall. 
           [0024]      FIG. 12  is a side view in section illustrating a wall with a hole formed in one sheet thereof, and foam bridging elements extending between two wall sheets. 
           [0025]      FIG. 13  is a side view in section illustrating the wall of  FIG. 12  with a cup holding expanding foam. 
           [0026]      FIG. 14  is a side view in section illustrating the wall of  FIG. 13  with the expanding foam expanded to fill the interior of the wall at the hole. 
           [0027]      FIG. 15  is a side view in section illustrating the junction of two wall sheets with foam placed in a gap at the junction. 
           [0028]      FIG. 16  is a side view in section illustrating wall of  FIG. 15  with a plaster layer spread over the foam. 
       
    
    
       [0029]    In describing the preferred embodiment of the invention which is illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, it is not intended that the invention be limited to the specific term so selected and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. For example, the word connected or term similar thereto are often used. They are not limited to direct connection, but include connection through other elements where such connection is recognized as being equivalent by those skilled in the art. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0030]    A conventional wall sheet  10  is shown in  FIG. 1 , which is shown as a conventional sheet of drywall, but which can be plywood or particle paneling, or any other conventional wall sheet material. A hole  12  is formed in the wall sheet  10 , and is defined by the edge  14 . Such a hole can be caused by various actions, but once the sheet  10  is cut back to a sound region, it is irrelevant how the hole  12  was caused. The edge  14  has been cut, for example by a conventional utility knife, to have a tapered edge  14 . The tapering of the wall  10  to a smooth edge, such as the edge  14 , has advantages. The original edge may have been jagged, tapered in the opposite direction, or otherwise less sound than the edge  14 . Nonetheless, the edge  14  is formed so that any adhesive properties of materials used in the repair of the hole  12  are maximized by forming the clean, tapered edge  14 . 
         [0031]    The wall sheet  10 , which is in the front of a conventional residential wall, is shown in  FIG. 3  in a preferred relationship with a back wall sheet  20 . The sheets  10  and  20  are oriented substantially parallel with one another, and with two support members, such as the wooden beams (“studs”)  30  and  40 , attached to inner surfaces of both sheets  10  and  20 . The beams  30  and  40  are interposed in the gap between the two sheets  10  and  20 , and are, for example, about one and one half inches thick by about three and one half inches wide by about eight feet long. A plurality of screws (not shown) extend through the sheets  10  and  20  into the beams  30  and  40 , thereby connecting the components to form a rigid wall structure in a conventional manner for a residential interior wall. Of course, the invention can be used in commercial and industrial walls, as well as exterior walls that have a solid panel or other surface spaced from the wall sheet that is being repaired. 
         [0032]    A fluent material, such as expanding foam  50 , is injected in the hole  12  as shown in  FIG. 2 . A suitable expanding foam is that sold under the trademark GREAT STUFF by The Dow Chemical Company. The fluent material is applied to the sheet  20  in order to adhere to the sheet  20 . As the foam expands away from the sheet  20 , toward the sheet  10 , the user applies foam to the surface of the existing foam  50  that is closest to the user. Thus, the foam first applied to the sheet  20  becomes the base for later-applied foam. In another embodiment, the foam  50  is first applied to the edge  14 , and as it expands to the back sheet  20 , more foam is injected into the hole  12 . The term “foam” is used herein to describe a solid material that occupies substantially more of its volume by sealed gaseous pockets within the volume than by solid material that forms the pockets around the gas therein. Some foam has pockets that are not sealed. Of course, there are materials that are not foams that could substitute for the material described herein, including, but no limited to, urethanes, epoxies and other polymer-based materials. 
         [0033]    Regardless of how it is applied, the foam  50  expands to fill the hole  12 , adhere to the interior surface of the sheet  10  near the edge  14 , adhere to the back sheet  20  and can expand beyond the hole  12  to form a convex “dome” on the sheet  10 . As shown in  FIG. 3 , the foam  50  expands between the sheets  10  and  20 , and, upon curing, strongly adheres to the inwardly facing surfaces of the sheets  10  and  20 . By expanding to fill at least a portion of the gap between the sheets  10  and  20 , the rigid cured foam  50  provides a support around the hole  12  that extends from the edge  14  to the back sheet  20 . Thus, forces exerted on the wall sheet  10  toward the sheet  20  are resisted by the resistance of the foam  50  to compression, and the resistance of the sheet  20  to deflection and separation from the beams  30  and  40 . The support provided by the cured foam  50  is substantial, and reduces the possibility that the repaired area will be damaged again. 
         [0034]    Once cured, the foam  50  is substantially rigid and is not tacky, and it can be cut or otherwise formed. Thus, as shown in  FIG. 4 , the foam  50  can be cut, for example by a flexible blade, such as a hacksaw blade or a flexible reciprocating saw blade, so that its exposed face is flush with the planar surface of the wall sheet  10 . More preferably, the foam  50  is cut to have an exposed surface that is concave, and its outer edges adjacent the edge  14  are substantially flush with the edge  14 , and a center that is recessed from the planar surface of the wall sheet  10 . 
         [0035]    Small pores are formed in the exposed surface of the foam  50  during expansion of the foam in its liquid or semi-liquid state, or after curing when the foam is cut or sanded to conform to the surface of the wall sheet  10 . These pores form sites for substantial adhesion of a paste plaster  60  to the foam  50 . The plaster  60  is preferably a conventional general purpose plaster or topcoat plaster, and can include an accelerator additive normally added to plaster. The plaster  60  is applied to the exposed surface of the foam  50  with a spatula, blade or other conventional tool, and smoothed with a similar conventional tool. The plaster  60  adheres to the foam  50  and the planar surface of the wall sheet  10 , and is smoothed to form a continuous planar surface with the wall sheet  10  as shown in  FIG. 6 . Once dried or cured, the plaster forms a surface on the wall sheet  10  that appears no different than the surface of a conventional repair. Upon curing, the plaster  60  can be sanded and then primed and painted to match the wall sheet  10 . 
         [0036]    The fluent material inserted or otherwise placed in the hole of a wall can be a relatively thick (high viscosity) material that will adhere to the wall sheets and avoid flowing down into the wall cavity. The expanding foam sold under the trademark GREAT STUFF has these characteristics. Alternatively, other fluent materials, such as water-cured urethanes, two-part self-curing urethanes and expanding urethanes have lower viscosity and greater density when first mixed. Such materials are of low enough viscosity that they will not stay in place on the edge of a hole or surface of a wall sheet before they expand to the desired size. Such materials are considered advantageous in some situations, and therefore it may be desirable to interpose bridging structures between the sheets  10  and  20  making up the wall. Such bridging structures support the fluent material enough during its curing, during which it forms into a foam, that the final foam structure is formed where desired. 
         [0037]    An example of such a bridging structure is the aluminum mesh  125 , which can be conventional insect screen, that is formed into the shape of a basket and placed in the hole  112 . The mesh  125  is formed into the shape of a “basket” and compressed slightly to fit between the back wall sheet  120  and the front wall sheet  110 , as shown in  FIGS. 7 and 8 . Because the mesh  125  is elastically deformable, and has a noticeable rebound from the deformation, the mesh  125  expands when the compressive force is released, in order to seat against the inwardly facing surfaces of the front wall sheet  110  and the back wall sheet  120 . Thus, the mesh  125  is “wedged” or compressed between the wall sheets  110  and  120 , and stays in place as shown in  FIG. 8  due to frictional forces. If desired, one can staple, glue or otherwise fasten the mesh  125  to the back wall sheet  120 , front wall sheet  110  or both. 
         [0038]    Once the mesh  125  is in place as described above, fluent material, such as the expanding foam  150 , is sprayed into the hole  112  as shown in  FIG. 9 . The expanding foam  150  contacts the mesh  125 , and adheres thereto. If the foam  150  is sprayed into the hole  112  at the edge  114 , it adheres to the mesh and front wall sheet  110 , as shown in  FIG. 10 . Upon further spraying of the foam  150  into the hole  112 , the gathering body of foam expands through the openings in the mesh  125  to adhere to the back wall sheet  130 , the wall sheet  110  and the edge  114 . Although it does not contain mesh, the illustration of  FIG. 3  is also an accurate depiction of the foam  150  after fully expanding and curing, because the mesh  125  provides little to no resistance to the expanding and adhering of the foam  150 . 
         [0039]    As with the embodiment of  FIG. 4 , the excess foam  150  can be cut away so that the exposed foam surface is flush with the planar finished surface of the wall  110 , or slightly recessed, as shown in  FIG. 11 . A roughly cut foam  150  is shown with some regions protruding slightly from the edge  114 . It will become apparent to a person having ordinary skill in the art that such edges can be removed by scraping, sanding or other chemical or mechanical action, all of which are considered “cutting”. It is not considered critical how such portions of the foam  150  are removed. It will also be apparent that these edges can be left intact, especially if by skillful application of plaster one can cover them and feather the plaster as is conventionally known. 
         [0040]    It will become apparent that instead of a mesh bridging member, compressible foam, such as expanded polystyrene (EPS) sold under the trademark STYROFOAM, can be cut into the small blocks  202  and  204 , compressed slightly, inserted in the gap between the front and back wall sheets  210  and  220 , and then released to expand to fill the gap, as shown in  FIG. 12 . Similarly, flexible materials, such as plastic sheeting, sheet metal, paperboard, corrugated paperboard, fiberglass insulation and composites, can be trimmed to the exact size needed or slightly larger and then bent, inserted into the gap and allowed to expand. Each of these structures provide a bridging support on which the fluent material can rest while it fills the hole and chamber behind the hole, in order to prevent or reduce loss of the fluent material due to flowing away from the hole. 
         [0041]    In the embodiment of  FIG. 12 , the fluent material is placed in a small vessel, such as a cup  206  and the cup is placed on the block  202 , as shown in  FIG. 13 . As the fluent material  250 , which will become the foam, expands and flows over the edges of the cup  206 , the cup sidewalls restrain the fluent material  250  from flowing away from the hole. The cup  206  is thus encapsulated by the expanded and cured foam  250 , which has no negative effect on the function of the foam. In this alternative embodiment, a planar panel, such as a transparent acrylic sheet  260 , is placed over the hole  212  to prevent expanding foam from expanding significantly beyond the wall surface, but still permitting the foam  250  to adhere to the edge  214  of the hole  212  and shown in  FIG. 14 . The planar panel can, of course, be another material, such as metal, composite or plastic. Additionally, a release agent, such as a sprayed film, or a sheet, such as wax paper, can be applied to the planar panel to make removal from the cured or semi-cured foam  250  much easier. 
         [0042]    In a particularly desirable embodiment, the fluent material  250  was mixed in a static mixer as it was dispensed from a pair of tubes that kept the two parts separated. Of course, the components can be mixed in a single tube with two separate compartments. The mixture began to react visibly and foam, and within about five minutes the hole was covered and the foam cured enough that the planar panel could be removed. Within fifteen minutes the foam was cured enough to sand. The foam was then topped with pure drywall compound accelerator, which was then allowed to cure. The drywall accelerator can be advantageous in some circumstances, but is not required. The drywall compound accelerator was a type of paste plaster, but it hardened within a few minutes, and was able to be sanded within ten minutes when dried using a conventional hair dryer. 
         [0043]    The term “hole” is used above to refer to an opening entirely through a wall sheet that exposes the cavity behind the wall sheet extending to the parallel wall sheet. However, the invention has substantial advantages when used in a hole that extends only partially through a wall sheet, or even between wall sheets, such as in a crack in drywall, or a groove between adjacent drywall sheets. For example,  FIG. 15  shows a groove  312  formed at the junction of two sheets of drywall  310  and  320  that are mounted against a stud  330 . The groove  312  is a conventional formation when the tapered edges of two sheets of conventional drywall are abutted and attached to a stud, although the groove size is exaggerated for illustrative purposes. Conventionally, drywall mud and tape are placed in the groove. According to an embodiment of the invention, however, a foam  350  is applied to the groove, as shown in  FIG. 15 . Once cured, the foam  350  can be cut back to below the facing surface of the sheets  310  and  320 , if necessary, as shown in  FIG. 16 , and then a thin coat of paste plaster  360  is applied over the foam  350 . The plaster  360  provides a finished surface that is continuous with the surfaces  310 ′ and  320 ′ of the sheets  310  and  320 , respectively. The foam remains flexible and allows for thermal expansion and contraction, which reduces or eliminates reflective cracking through the plaster  360 . Thus, this embodiment of the invention is used to fill large gaps and grooves with foam that cures and hardens. Subsequently, a thin coat of plaster is used to provide an attractive finished surface. 
         [0044]    Other foam materials can be used to fill the large gaps and holes in wall surfaces. For example although one acceptable foam is GREAT STUFF brand expanding foam, which is water-cured, it is also contemplated to use two-part material that is mixed together and does not require moisture in air to cure. Other materials will become apparent to the person having ordinary skill from the description herein. 
         [0045]    It is also contemplated, instead of placing uncured foam in a hole and then permitting the foam to cure and harden, to include cutting already cured foam to fit a hole and adhering it in place. Of course, other materials that are suitable can also be used in place of the cured foam, such as wood, plastic or any other solid material. For example, a block of EPS can be cut to fit the inner diameter of the hole  12  in  FIG. 1 , so that it has a thickness substantially equal to the distance between the front face of the wall sheet  10  and the surface of the wall sheet  20  that faces toward the wall sheet  10 . Such a foam block (not shown) can be inserted in the hole  12  and adhered to the sheet  20  (using, for example, double-sided tape, adhesive, staples, etc.). Once this is constructed, the invention is carried out as with the preferred embodiment, insofar as a thin coat of plaster is applied to the foam and drywall to fill any cracks and cover the exposed face of the foam. Alternatively, the foam block can have a drywall disk adhered or otherwise attached to the face to make finishing easier and final strength even greater. Likewise, self-adhesive, pre-cured foam tape can be applied over grooves, such as the groove  312  in  FIG. 15 , and then a coat of plaster is applied to form a finished surface. 
         [0046]    The resulting structure preferably extends a support from the face of the wall sheet being repaired to the wall sheet that is not accessible when the wall is closed. Then that support is coated with plaster to give a finished appearance. Of course, such a structure can be made with a small bladder substituting for the foam or EPS, with a small nozzle to permit it to be pumped up in the wall cavity to the desired hardness. 
         [0047]    This detailed description in connection with the drawings is intended principally as a description of the presently preferred embodiments of the invention, and is not intended to represent the only form in which the present invention may be constructed or utilized. The description sets forth the designs, functions, means, and methods of implementing the invention in connection with the illustrated embodiments. It is to be understood, however, that the same or equivalent functions and features may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the invention and that various modifications may be adopted without departing from the invention or scope of the following claims.