Abstract:
A method and apparatus for forming a waterproof building wall is disclosed, including providing a mold that fits around a window or other structure held in the wall, applying stucco or other moldable material that hardens to form an exterior coating for the wall and a recess from the mold, and sealing the recess with an elastic and waterproof sealant that is attached to both the structure and the side of the recess. The resulting wall may have a sealed recess between the stucco coating and the structure that extends less than about one centimeter from the structure, and the seal can expand and contract in conformance with expansion and contraction of a distance between the edge and the side surface.

Description:
TECHNICAL FIELD  
         [0001]    The present application relates to sealing building walls containing structures that are exposed to the exterior of the building, such as windows, pipes and doors.  
         BACKGROUND  
         [0002]    Provision of buildings with interior regions that are protected from the elements is one of the most basic and longstanding human needs. Various forms of wall materials are commonly employed, such as wood, masonry, concrete and stucco. Typically, glass windows are attached to the walls with window frames, which are commonly made of wood, aluminum or vinyl. Areas at which window frames or other structures meet building walls sometimes have leaks that allow air and/or water to enter the walls, and so those areas are typically protected with waterproofing such as flashing.  
           [0003]    For new construction of homes in North America, walls are commonly built with wood frames and stucco exterior coatings. In this case, building paper is stapled to the exterior side of the wood wall frame, and then a wire mesh is nailed to the frame through the building paper. The wire mesh provides support for one or more layers of portland cement plaster that hardens to form a stucco coating for the exterior wall. Water that seeps through the stucco coating, for example via cracks that may develop in the stucco, is designed to be obstructed by the building paper and drip to the bottom of the stucco coating, where it is diverted outside the wall again at a weep screed.  
           [0004]    To build a wall containing a window opening or other structure that pierces the stucco layer, the structure is first attached to wood support members such as the studs, lentil and sill plate that form a rough opening in the wall. Flashing material is then typically attached to the support members surrounding the structure prior to attachment of the building paper. Despite these precautions, moisture sometimes penetrates the wall from the exterior to cause damage. Prolonged exposure to moisture can cause the wood in the walls to rot, and excessive moisture can ruin interior elements such as carpet and wallboard. Even temporary exposure to moisture can cause mold to develop, which may cause respiratory and other problems in some people.  
           [0005]    [0005]FIG. 1 shows a window  20  that has a vinyl frame  22  attached to a wall that is coated with stucco  25 . The vinyl frame  22  may expand and contract more than the stucco wall coating  25 , causing leaks to develop at a juncture between the frame and the stucco. To repair such leaks the stucco that is located within about one foot of the window may be removed, after which the window flashing may be repaired and the removed stucco replaced. Unfortunately, the window frame may again expand and contract more than the repaired stucco, so that leaks reappear.  
           [0006]    Alternatively, the stucco coating  25  may be sawed with a diamond-tipped blade along edges of the window frame  22  to create gaps  30  that are then sealed with waterproof caulk. The saw blade typically leaves notches  33  that extend beyond corners of the window frame  22  by an inch or more. The notches can be unsightly even after they are caulked and painted. In addition, hairline cracks  35  in the stucco  25  may develop that propagate from the notches  33 , further marring the appearance and further reducing the structural integrity of the stucco coating.  
         SUMMARY  
         [0007]    A method and apparatus for forming a waterproof building wall are disclosed, including providing a mold that fits around a window or other structure held in the wall, applying stucco or other moldable material that hardens to form an exterior coating for the wall and a recess from the mold, and sealing the recess with an elastic and waterproof sealant that is attached to both the structure and the side of the recess. The resulting wall may have a sealed recess between the stucco coating and the structure that extends less than about one centimeter from the structure, and the seal can expand and contract in conformance with expansion and contraction of a distance between the edge and the side surface. 
       
    
    
     DESCRIPTION OF THE FIGURES  
       [0008]    [0008]FIG. 1 is a cutaway side view of a prior art means for fixing a leaking window in a stucco wall.  
         [0009]    [0009]FIG. 2 is a cutaway side view of a window contained in a stucco wall and having a molded recess sealed with a waterproof elastic seal.  
         [0010]    [0010]FIG. 3 is a cutaway cross-sectional view of the stucco wall and window of FIG. 2.  
         [0011]    [0011]FIG. 4 is an expanded cutaway cross-sectional view of a seal between the stucco wall and window of FIG. 3.  
         [0012]    [0012]FIG. 5 is an expanded cutaway cross-sectional view of a seal between a one-coat stucco wall and a window structure, with a foam board disposed beneath the seal.  
         [0013]    [0013]FIG. 6 is an expanded cutaway cross-sectional view of a seal between a one-coat stucco wall and a window structure, with a foam board disposed beside the seal.  
         [0014]    [0014]FIG. 7 is a side view of a window having a removable mold fitting around the frame to shape the stucco wall of FIG. 2.  
         [0015]    [0015]FIG. 8 is a cross-sectional view of the window and removable mold of FIG. 7.  
         [0016]    [0016]FIG. 9 is an expanded cutaway cross-sectional view of the window frame and mold of FIG. 8.  
         [0017]    [0017]FIG. 10 is a cutaway cross-sectional view of the window frame and a mold having an acute angle between the flange and the projection.  
         [0018]    [0018]FIG. 11 is a side view of several individual molds that can be arranged to encircle a window frame.  
         [0019]    [0019]FIG. 12 is a cutaway cross-sectional view of the window frame and mold of FIG. 9 with stucco formed around the mold.  
         [0020]    [0020]FIG. 13 is a cutaway cross-sectional view of a mold that is held to window frame with tape.  
         [0021]    [0021]FIG. 14 is another cutaway cross-sectional view of the mold of FIG. 13 held to window frame with tape at an angle to normal from an exterior surface of the frame.  
         [0022]    [0022]FIG. 15 is a cutaway cross-sectional view of an L-shaped mold that is held to window frame with tape.  
         [0023]    [0023]FIG. 16 is a cutaway cross-sectional view of a J-shaped mold that is held to window frame with tape.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0024]    [0024]FIG. 2 shows a window  50  with a frame  52  that is attached to a wall that is coated with stucco  55 . The window  50  and frame  52  may be generally rectangular as shown or may have a variety of other known window shapes, such as curved or circular, which are not shown but can also be employed with the invention. The frame  52  may be made of wood, aluminum and/or vinyl, or other known materials. The stucco  55  may be made of a single layer or several stucco layers, as described below. Also, other suitable materials may be used instead of stucco, such as plastic and/or cement, and other structures may be used instead of the window, such as pipes, doors, beams, vents, etc.  
         [0025]    A molded recess  60  has been formed in the stucco  55  and filled with a waterproof elastic seal. In one embodiment, the recess and seal generally extend no more than about one centimeter (approximately one-half inch) from the outside edge of the window frame  52 , eliminating the notches of the prior art and their various problems. In one embodiment, the recess and seal may extend from the frame between about two millimeters (approximately one-sixteenth inch) and six millimeters (approximately one-quarter inch), and preferably between about three millimeters (approximately one-eighth inch) and six millimeters (approximately three-eighths inch). In contrast with the prior art, the recess may be so thin that it may not need to be painted after it has been filled with sealant. The sealant may be available in various colors that match either the stucco or the frame so that the exposed sealant is not noticeable. An adherent layer, not shown, may be applied between the sealant and the paint, or the sealant may be painted while still tacky to affix the paint to the sealant.  
         [0026]    [0026]FIG. 3 shows a cross-sectional view of the stucco-coated wall and window of FIG. 2. Also shown in FIG. 3 are wall support members  70  such as wood or metal two-by-fours or two-by-sixes, and an interior coating  75  such as wallboard. For conciseness, the window  50  and frame  52  are illustrated as having a simple fixed double-pane structure.  
         [0027]    [0027]FIG. 4 shows an expanded cross-sectional view of the area enclosed by the dashed circle  77  of FIG. 3. Stucco coating  55  can be seen in this embodiment to be made of three layers: a scratch coat  80 , a brown coat  82  and a finish coat  85 , which are applied in that order over a waterproof building paper layer  90 . The finish coat  85  has an exterior surface  95  that may be exposed or painted. The stucco coating  55  may have an overall thickness of about two and one-quarter centimeters (approximately seven-eighths inch).  
         [0028]    The window frame  52  has a fin  92  that is attached to the support members  70 , for example by nailing. The recess  60  has a bottom surface  98  and a side surface  102 , and the side surface is substantially perpendicular to the exterior surface  95  in this embodiment. Alternatively, the side surface  102  may slope toward the frame with increasing depth from the exterior surface  95 , so that the recess adjacent to the bottom surface is essentially the same distance from the frame as that adjacent to the exterior surface, where the frame has a small lip. The recess may have a depth-to-width aspect ratio that is in a range between about one and about six.  
         [0029]    A foam rod  105  may be disposed in the recess  60  adjacent to the bottom surface  98 , and an elastic and waterproof sealant  110  fills the remainder of the recess to join with the side surface and with an edge  108  of the frame. The rod  105 , which may be hydrophilic, ensures that the sealant  110  is disjoined from the bottom surface  98  despite being bonded to the side surface to the edge  108 , and also reduces the depth-to-width aspect ratio of the remainder of the recess to facilitate filling the remainder of the recess with sealant. The sealant preferably can expand to several times its original thickness, remaining secured to the edge  108  and to the side surface of the recess even as the window frame contracts much more than stucco, expanding the distance between the edge  108  and the side surface. The sealant is also non-reactive with the window frame material, and the sealant may therefore differ depending upon the type of material used for the window frame. In one embodiment, the sealant is product number 1199 SSL silicone sealant available from Dow Corning Corp., PO Box 0994, Midland, Mich. 48686-0994, which is non-reactive with both vinyl and aluminum and has an expansion coefficient of approximately four. The expansion coefficient is a measure of how far a material can stretch without permanent deformation. This sealant typically does not provide a surface to which most paints adhere, but a paintable silicon layer can be applied as a kind of primer that provides adhesion for paint. Paint can then be applied while the primer is still tacky or after curing. In an alternative embodiment, a sealant that does not stretch as much but is paintable can instead be used, provided the sealant has an expansion ratio of at least one.  
         [0030]    [0030]FIG. 5 is a cross-sectional view of an embodiment similar to that shown in FIG. 4 but having a single stucco layer  120  applied atop a board  122  that may be made of foam or wood. The embodiment shown in FIG. 5 may be termed a “one-coat” stucco process, as opposed to the “three-coat” process described with reference to FIG. 4, although it need not have only one coat atop the board  122 . The foam or other board  122  may be a “blue board” that includes drip lines, available from Dow Corning at the above address, and the stucco layer  120  may include fibers and plastic as well as concrete. The frame for the one-coat process may have a greater distance between the fin  92  and the exterior surface  95  to allow for the board and stucco. In the embodiment of FIG. 5 the foam board  122  forms the bottom surface of the recess  98 . As will be discussed, the stucco is formed to a mold that is then removed to leave a recess  125  that has a smaller depth-to-width aspect ratio than that of the embodiment of FIG. 4.  
         [0031]    The sealant  110  may be selected to avoid adherence with the foam board  122 , or the foam board may be coated with a material, such as a powder, paint or strip, that does not adhere well to the sealant. The waterproof and elastic sealant  110  is selected to adhere well to the side surface  102  and to the edge  108 . Freeing the sealant from the bottom surface  98  helps the sealant remain affixed to the side surface  102  and to the edge  108  as the distance between the side surface and the edge changes, instead of pulling the sealant toward the bottom surface during expansion of that distance and pushing the sealant away from the bottom surface during contraction of that distance.  
         [0032]    [0032]FIG. 6 is a cross-sectional view of an embodiment similar to that shown in FIG. 5, except that the foam board  122  terminates at the side surface  102  of the recess instead of extending beneath the bottom surface  98  of the recess. This can be formed by abutting the foam board  122  to a mold insert that is removed after the stucco has hardened, instead of abutting removable mold to the foam board to form the embodiment of FIG. 5. A foam rod  105  is disposed in the recess  125  adjacent to the bottom surface  98  to disjoin the sealant  110  from the bottom surface. The foam rod  105  may be termed a bond breaker and may be hydrophilic. Tape or other bond breaking material may be disposed in the recess adjacent to the bottom surface, instead of the foam rod. The foam board may have a thickness in a range between about two and one-half centimeters (approximately one inch) and about three centimeters (approximately one and one-quarter inch) and the stucco layer may have a thickness in a range between about six millimeters (approximately three-eighths inch) and about one centimeter (approximately one-half inch) in this embodiment.  
         [0033]    [0033]FIG. 7 shows the window  50  with a removable mold  155  fitting around the window frame  52  to shape the stucco wall of FIG. 2, and thereby create any of the structures shown in FIG. 3 to FIG. 6. The mold  155  is shaped to fit closely around the window frame  52 , which may be produced to tight tolerances by various window manufacturers. The mold may be provided with the window  50  or may be separately supplied and fitted to the window frame  52 . The mold may be made of plastic, metal, wood or any other suitable material that detaches from the stucco to form a recess in the stucco layer adjacent to the frame.  
         [0034]    [0034]FIG. 8 is a cross-sectional view of the window  50 , frame  52  and mold  155  of FIG. 7. The mold  155  in this embodiment includes a projection  157  and a flange  158  that extend substantially at right angles to each other. The projection  157  is used for molding the stucco while the flange  158  helps to hold the projection  157  to the frame  52  at a correct and uniform depth from the face of the frame, creating a uniform recess in the stucco.  
         [0035]    [0035]FIG. 9 shows an expanded cross-sectional view of the area enclosed by the dashed circle  160  of FIG. 8. Mold  155  can be seen in this embodiment to have a rounded corner that provides room for creating a textured finish for the stucco. Alternatively, the mold can have a square corner for creating a screed finish on the stucco. Projection  157  may have a depth D in a range between about three centimeters (approximately one and one-half inch) and about five millimeters (approximately one-quarter inch), depending upon the embodiment. Projection  157  may have a width W in a range between about two millimeters (approximately one-sixteenth inch) and six millimeters (approximately one-quarter inch), and preferably between about three millimeters (approximately one-eighth inch) and six millimeters (approximately three-eighths inch). Flange  158  may have a height H similar to the width W of the projection  157 . Alternatively, the flange  158  may be thicker than the projection  157  to provide a more pronounced edge for guiding a stucco working tool such as a trowel, or the flange  158  may be reduced in thickness to allow a stucco tool such as a trowel to screed over the flange in forming an exterior surface of the stucco. In the latter case, flange  158  may have a height H in a range between about one millimeter and about three millimeters, and preferably about two millimeters (approximately one-sixteenth inch).  
         [0036]    [0036]FIG. 10 is a cross-sectional view of an embodiment similar to that shown in FIG. 9, except that the projection  157  forms an acute angle with the flange  158 . The recess formed in the stucco by projection  157  will have a side surface that is not perpendicular to the exterior surface of the stucco.  
         [0037]    [0037]FIG. 11 shows several individual molds  180 ,  182 ,  184  and  186  that can be arranged to encircle a window frame. The molds  180 ,  182 ,  184  and  186  each have a projection and a flange that are at a right angle to each other, with the projections extending away from the viewer in this figure. Each of the projections also extends further than its attached flange along the elongate dimension of that mold, so that the flanges do not interfere with each other when the molds are attached to a window frame. For example, mold  182  has a projection  188  attached to a flange  190  that is clipped at its ends  192  and  194  so that the flange extends less than the projection in the elongate dimension of the mold. The individual molds  180 ,  182 ,  184  and  186  may be held to a window frame by tape, glue or similar means.  
         [0038]    [0038]FIG. 12 shows mold  155  fitted on window frame  52  with stucco  55  formed up to the mold. After the stucco  55  has hardened and the mold  155  removed, a recess remains in the stucco where the projection  157  had been disposed. The recess can then be sealed with a bond breaking material and sealant as illustrated above.  
         [0039]    [0039]FIG. 13 shows a mold  200  held to a window frame  52  with tape  202  that wraps around a projection  205  to become part of the mold. The tape  202  has a reduced thickness (e.g., approximately one millimeter) to allow a stucco tool such as a trowel to screed over the tape to form an exterior surface of the stucco that is substantially coplanar with the frame  52 .  
         [0040]    [0040]FIG. 14 shows mold  200  held to window frame  52  with tape  202  such that the mold is not perpendicular to the frame surface to which the tape is attached. As mentioned above, the tape  202  has a thickness (e.g., two millimeters or less) to allow a stucco tool such as a trowel to screed over the tape to form an exterior surface of the stucco that is substantially coplanar with the frame  52 .  
         [0041]    [0041]FIG. 15 shows a mold  210  held to a window frame  52  with tape  202  that wraps around a projection  215  to become part of the mold. The mold has a lip  212  that extends from the projection  215  toward frame  52  a similar distance as a lip  220  of the frame extends away from the remainder of the frame, so that projection  215  extends in a direction perpendicular to the frame surface to which the tape is attached. The mold lip  212  may be thinner than the projection  215  to facilitate removal of the mold after the stucco or other moldable material has hardened.  
         [0042]    [0042]FIG. 16 shows a mold  230  held to a window frame  52  with tape  202  that wraps around a projection  235  to become part of the mold. The mold has a lip  237  that extends from the projection  235  toward frame  52  a similar distance as a lip  220  of the frame extends away from the remainder of the frame, so that projection  235  extends in a direction perpendicular to the frame surface to which the tape is attached. The mold lip  237  may be curved to facilitate removal of the mold after the stucco or other moldable material has hardened. The molds shown in FIG. 15 and FIG. 16 may have particular utility for windows that have curved frames, such as arched or circular windows.  
         [0043]    Although the present disclosure has focused on teaching the preferred embodiments, other embodiments and modifications of this invention will be apparent to persons of ordinary skill in the art in view of these teachings. Therefore, this invention is to be limited only by the following claims, which include all such embodiments and modifications when viewed in conjunction with the above specification and accompanying drawings.