Abstract:
An easily constructed and highly durable structure, and method of making the same. The structure is constructed of lightweight foam panels assembled into walls and a roof, and therefore requires no framework. The entire structure is then sprayed with a cementitious coating. The cementitious coating is applied directly to the foam panels, and dries with sufficient strength and durability to make the structure load-bearing.

Description:
RELATED PATENT APPLICATIONS  
       [0001]    This patent application is a continuation of U.S. Ser. No. 09/490,505, filed Jan. 25, 2000, which claims priority to United States Provisional Application No. 60/117,115, filed Jan. 25, 1999, and entitled FRAMEWORK-FREE BUILDING SYSTEM AND METHOD OF CONSTRUCTION; said applications in their entirety are hereby expressly incorporated by reference into the present application. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    This invention relates to a foam panel building system that is bonded together with a sprayed-on cementitious coating that forms a load-bearing shell around the entire structure.  
           [0003]    There are numerous methods for constructing homes and building structures, and each have their benefits and drawbacks. The most common home building method in the United States, for instance, involves building a wood frame structure, which is then faced with brick or siding of a variety of materials, and finished with drywall and paint on the interior. Building such a home takes considerable time, requires workers with a variety of skilled trades, and incorporates numerous different materials. While this building method is highly flexible, it is often quite costly.  
           [0004]    The most common building method throughout the rest of the world involves building a structure with blocks made of a wide variety of materials, including mud, brick, or concrete. While relatively simple and inexpensive to construct, such building methods are time consuming, often require skilled laborers, and frequently require materials not readily available in every location.  
           [0005]    There are many places in the world that are without the necessary building materials and skilled workers, and where the local population cannot afford to construct homes. Thus, there is a need throughout the world for buildings that are highly durable, yet quick, easy, and relatively inexpensive to construct. This invention meets that need by providing a structure that requires few components and is quick and simple to construct, resulting in a relatively inexpensive method of construction.  
           [0006]    There are a number of patents covering lightweight foam panel buildings covered with cementitious material, but none have the features of this design. One of the earliest is U.S. Pat. No. 3,676,973, issued on Jul. 18, 1972 to Kellert, which contains an elaborate structural framework, and also requires a wire screen for application of sprayed on concrete. Another example is seen in U.S. Pat. No. 4,292,783, issued on Oct. 6, 1981 to Mulvihill, which requires the use of a temporary framework to assemble the panels, and then requires a rigid steel wire mesh for application of a gunnite concrete layer. A third example, U.S. Pat. No. 4,342,180, issued Aug. 3, 1982 to Gibson et al., requires a steel framework to hold the panels in place, and requires wire mesh for application of the concrete. The necessity of a framework, either temporary or permanent, increases the cost and complexity of the building method. The present invention does not require a framework to hold the structure in place, making it easier, quicker and cheaper to use.  
           [0007]    One unique aspect of this invention is that the cementitious material is sprayed directly on the structure without the need for wire or other meshing to hold the material, unlike stucco or other conventional materials.  
           [0008]    The current art contains a number of spray-on cementitious materials, which have two drawbacks. Many cannot be applied directly to a surface, requiring the use of a wire or mesh covering over the surface. Others can be applied directly to a surface, but provide no structural support. The present invention does both.  
           [0009]    Examples of prior art in these categories includes U.S. Pat. No. 4,774,794 issued Oct. 4, 1988 to Grieb, which discloses pre-made foam blocks with a cementitious coating. The coating is applied on a fiberglass reinforcement mat laid over the surface prior to the application of the coating. While these blocks are of sufficient strength to create a load-bearing structure, they have the disadvantage of requiring a mesh to apply the cementitious coating. A similar example is U.S. Pat. No. 4,150,175 issued Apr. 17, 1979 to Heutteman, discloses a building panel made from a honeycombed core panel covered with a thin, strong concrete coating. Both inventions require assembly after coating.  
           [0010]    A second unique aspect of the present invention is that the cementitious material dries hard enough to make the material load-bearing. There are many spray-on materials known in the art, such as cement or stucco, but these do not add structural strength or support to the building. There are a few patents on the direct application of cementitious materials to a surface, but none produce a structure that has load-bearing properties. For example, U.S. Pat. No. 4,067,164, issued Jan. 10, 1978 to McMillan, shows a panel with a direct application of cementitious materials, which provides protection to the underlying materials, but does not produce any structural benefits.  
           [0011]    Another example from the prior art is U.S. Pat. No. 5,771,649 issued Jun. 30, 1998 to Zwieg. It is drawn to a system of structural foam and plastic blocks, which are then coated with a sprayed on concrete. In Zwieg, the blocks provide structural support and the concrete provides a protective layer.  
           [0012]    From the preceding description of the prior art, it should be apparent that there is a need for a building system that is simple to build, yet structurally sound. This invention meets that need.  
         SUMMARY OF THE INVENTION  
         [0013]    The present invention is directed to a new foam panel building system that is bonded together with a cementitious coating that forms a load-bearing shell around the entire structure, and to the method of constructing this structure. The building system is comprised of a number of foam panels, a means for connecting the panels into wall units and a roof, and a cementitious coating applied directly to the walls and roof which forms a load-bearing shell.  
           [0014]    It is an object of the present invention to provide a more easily constructed and more durable building system than that which has previously been available in the industry. Moreover, the present invention provides a building system that is not only strong, but is also aesthetic in appearance. It can be easily adapted to incorporate a great variety of architectural details to suit a purchaser&#39;s specific needs. Importantly, the invention also provides a low-cost housing alternative that is quick to construct.  
           [0015]    It is an additional object of this invention to provide a cementitious coating that is applied directly to a surface without the need for wire or mesh to hold the coating. It is a further object of this invention that this cementitious coating, once applied to a surface, provides sufficient strength and durability to create a load-bearing structural element.  
           [0016]    The method of constructing this structure comprises the steps of building a foundation, attaching panels to create walls, attaching walls to the foundations and then to each other, attaching panels to create a roof, and applying a cementitious coating onto the walls and roof to form a load-bearing shell around the structure.  
           [0017]    Still other objects, features, and advantages of the present invention will be apparent from the following description of the preferred embodiments, given for the purpose of disclosure, and taken in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    [0018]FIG. 1 is a plan view of the preferred embodiment of the building system showing the location of the exterior and interior walls on the foundation.  
         [0019]    [0019]FIG. 1A is a cross-sectional view of a wall showing the cementitious material being sprayed in a thin coating to produce the load-bearing shell.  
         [0020]    [0020]FIG. 2 is a plan view of the foundation showing the location of the trenches under the exterior and interior walls.  
         [0021]    [0021]FIG. 3 is a cross-sectional view of the foundation at a cross-section showing the trench at the edge of the foundation beneath the exterior wall.  
         [0022]    [0022]FIG. 4 is a cross-sectional view of the foundation at a cross-section showing the trench under an interior wall.  
         [0023]    [0023]FIG. 5 is the front elevation view of the preferred embodiment showing multiple vertical foam panels positioned side-by-side and cut at a slant to match the pitch of the roof, and joined together to form the front wall.  
         [0024]    [0024]FIG. 6 is the back elevation view of the preferred embodiment showing multiple vertical foam panels positioned side-by-side and cut at a slant to match the pitch of the roof, and joined together to form the back wall.  
         [0025]    [0025]FIG. 7 is the right elevation view of the preferred embodiment showing multiple vertical foam panels positioned side-by-side and joined together to form the right wall.  
         [0026]    [0026]FIG. 8 is the left elevation view of the preferred embodiment showing multiple vertical foam panels positioned side-by-side and joined together to form the left wall.  
         [0027]    [0027]FIG. 9 is a detail view of an alternative embodiment showing the use of a spline as a connection between two adjoining wall panels.  
         [0028]    [0028]FIG. 10 is a detail view of an alternative embodiment showing the use of a spline as the connection between two adjoining corner wall panels.  
         [0029]    [0029]FIG. 11 is a detail view of an alternative embodiment showing the use of a spline as the connection between two adjoining exterior wall panels and an adjoining interior wall panel.  
         [0030]    [0030]FIG. 12 is a detail view of an alternative embodiment showing the use of a spline as the connection between two adjoining corner wall panels and an adjoining wing wall.  
         [0031]    [0031]FIG. 13 is an interior elevation view of the preferred embodiment showing multiple vertical foam panels positioned side-by-side and joined together to form a wall.  
         [0032]    [0032]FIG. 14 is a roof plan view of the preferred embodiment showing multiple foam panels positioned side-by-side and joined together to form the roof.  
         [0033]    [0033]FIG. 15 is a roof plan layout view of the preferred embodiment showing multiple foam panels before being joined.  
         [0034]    [0034]FIG. 16 is a detail view of an alternative embodiment showing the eave, the bevel cut on a wall, a notch cut into the underside of the roof to receive the top edge of the wall, an outer roof notch cut into the upper roof surface with an outer roof rib placed in the outer roof notch, and a spline connecting foam panels of the roof.  
         [0035]    [0035]FIG. 17 is a detail view of an alternative embodiment of the ridge of the roof, showing a bevel cut on the top edge of the interior wall, notches cut into the underside of the roof to receive the top edge of the wall, the apex roof notch cut into the apex of the roof, the apex roof rib placed in the apex roof notch, and splines connecting foam panels of the roof.  
         [0036]    [0036]FIG. 18 is a perspective view showing the assembled structure in the alternative embodiment with the hurricane straps and a door and windows.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0037]    Referring to the drawings, FIG. 1 shows a preferred embodiment of the present invention where the building system is a house  2  built on a concrete foundation  4  that is preferably a reinforced concrete slab. However, a wide variety of housing foundations may be used, as is well-known to those skilled in the art. In the most preferred embodiment, a welded wire mesh  9 , as shown in FIGS. 3 and 4, is used to reinforce the concrete and No. 6 mesh (the wires run perpendicular to each other at about 6 inch intervals). The wire fabric  9  is laid in a grid work pattern and is bent on the ends into a trench  10  that is excavated around the perimeter  8  of the concrete foundation  4 , as further shown in FIGS. 2 and 3. The foundation  4 , in another preferred embodiment, may be constructed with a system of I-beams placed under the perimeter  8  of the house  2  as well as under the interior walls  5 . Concrete is poured around the I-beams.  
         [0038]    The dimensions of the concrete foundation  4  should match the dimensions of the house  2  at ground level, plus any porches or patios affixed to the house  2 . The dimensions of the foundation  4  may be any size, but in the preferred embodiment of a small house, are about 24 feet by about 20 feet. In addition, the foundation  4  is in the range preferably of about 2 inches to about 6 inches in thickness. In one preferred embodiment of the invention, the concrete foundation  4  is about 2 inches thick across the entire foundation  4 , except where trenches  10  are formed around the perimeter  8  of the house  2  and under any walls  6  of the house  2 . Preferably, the trenches  10  are about 4 inches deep and about 6 inches wide and create additional support under the walls  6  of the house  2 . FIG. 3 shows a cross-section of the trench  10  across the line A-A in FIG. 2. FIG. 4 shows a cross-section of the trench  10  under an interior wall  6  of the house  2  across the line B-B in FIG. 2.  
         [0039]    As shown in FIGS. 5 and 6, the interior walls  5  and exterior walls  6  of the house  2  are constructed of foam panels  20 . The foam panels  20  may be made of expanded polystyrene (“EPS”), polyurethane or other foamed plastics. EPS panels cut to the proper size may be readily obtained from foam companies and are preferably modified EPS with a pound per cubic foot density in the range of about 1.0 to about 2.0 (Houston Foam Plastic, Houston, Tex.). In the preferred embodiment, the foam panels  20  are pre-cut and numbered consecutively so that they are easily assembled at the construction site and easily matched up with the house  2  drawings. The foam panels  20  may be any thickness, but preferably are in the range of about 3 inches to about 6 inches thick and most preferably are 4 inches thick. The foam panels  20  are preferably 4 foot wide rectangular foam panels  20  that are cut to create a length equal to the height  22  of the walls  6 .  
         [0040]    Referring to FIGS. 5 and 6, foam panels  20  that are about 4 feet wide fit together side-by-side vertically. The vertical joint  24  between the panels  20  is preferably joined with an adhesive product. However, other means for joining the panels  20  include tape, toothpicks, wood skewers, and other similar devices that may be used to temporarily secure foam pieces. In the preferred embodiment, Enerfoam® (Flexible Products Company of Canada, Inc., Ontario, Canada) is used between the foam panels  20 . The foam panels  20  of each wall  6  are glued together and then each wall  6  is glued to the other walls  6 . For example, FIG. 5 shows the panels  20  for the front  12  of the house  2  joined together. FIG. 6 shows the glued together panels  20  for the back  14  of the house  2 . FIGS. 7 and 8 show the joined panels  20  for the right  18  and left  15  sides of the house  2 . In addition, the panels  20  for the front  12  and back  14  are cut on the top edge  26  to match approximately the pitch of the roof  28 . In addition, the panels  20  for the left  16  and right  18  walls  6  are beveled  30  (cut on a slant) on the top edge  26  to about the same angle as the pitch of the roof  28 , as shown in FIGS. 7, 8, and  16 .  
         [0041]    In another embodiment of the present invention, the foam panels  20  are juxtaposed one above the other to form walls  6  instead of being juxtaposed vertically side-by-side. The horizontal panels  20  are attached to each other through the means described above.  
         [0042]    As shown in FIGS. 1 and 13, interior walls  5  of the house  2  are preferably constructed of the same foam panels  20  as used for the outer walls  6  of the house  2 . The foam panels  20  are pre-cut to a length  22  (FIG. 5) to match the distance from the foundation  4  (FIG. 1) to the roof  28  (FIG. 14) of the house  2  at the position where the interior and exterior walls  6  are placed. As shown in FIGS. 7, 8, and  13 , the top edge  26  of each panel  20  is preferably beveled  30  to approximately match the pitch of the roof  28 .  
         [0043]    Referring to FIG. 14, the roof  28  is constructed of foam panels  20  which may be cut in a wide variety of dimensions. In the preferred embodiment, the roof  28  is constructed of rectangular foam panels  20  which are about 8 inches thick, about 4 feet wide, and long enough to allow for about a 2 foot overhang  32  on the left  16  and right  18  sides of the house  2 . The roof thickness preferably varies from about 6 to about 12 inches. FIG. 14 shows a top view of the roof  28  where the panels  20  of the roof  28  are superimposed over the walls  6  of the house  2 . The roof overhang  32  preferably exists on all sides of the house  2 . FIG. 15 shows the same roof  28  layout prior to joining the roof panels  20  together. Preferably, the roof panels  29  for each side  16 ,  18  of the house  2  are joined together along the vertical joints  24  between the panels  20  with an adhesive material. Further, the top edge  27  of the panels  20  are joined by an adhesive material at the apex  34  of the roof  28 .  
         [0044]    [0044]FIG. 16 shows an alternative embodiment of the invention where the left side  16  and right side  18  of the walls  6  are received on their top edge  26  into a notch  36  cut into the roof panels  20 . FIG. 17 shows an embodiment of the invention where an interior wall  6  of the house  2  is positioned under the apex  34  of the roof  28 . The roof panels  20  contain a notch  36  that receive the top edge  26  of the wall panels  20 . Notch  36 , as shown in FIG. 16, is made one inch deep into roof panels  26  to receive the top edge  26  of wall panels  20 , which have bevel  30 . Also shown in FIG. 16 and FIG. 17, a 2-inch by 4-inch foam roof spline  42 , preferably constructed of a EPS foam, is used to join roof panels  26  along their side edges. Each roof panel  26  is notched to accommodate spline  42 .  
         [0045]    In another alternative embodiment of the invention, the roof panels  20  are cut with an outer roof notch  37  from the front  12  to the back  14  of the house  2 . The outer roof notch  37  is positioned over the walls  6  on the left  16  and right  18  sides of the house  2 . As shown in FIG. 16, the outer roof notch  37  is semi-circular and has a 3-inch diameter. The outer roof notches  37  on the left  16  and right  18  sides of the house  2  are then filled with an outer roof rib  38  that is cut to match the shape of the outer roof notches  37 . The outer roof rib  38  runs the entire length of the notch  37 . In another alternative embodiment of the invention, an apex roof notch  39  is cut along the top edge  27  of the roof panels  20 . The dimensions of the notch  39  may vary greatly but are preferably about 2 inches deep and about 2 inches wide to create a combined notch  39 , after the roof panels  20  are joined at their top edge  27 , of about 2 inches deep and about 4 inches wide. An apex roof rib  40  is cut to approximately match the shape of the apex roof notch  39 . The apex roof rib  40  is placed into the apex roof notch  39  and runs the length of the apex  34  of the roof  28 . As shown in FIG. 18, under the ribs  38 ,  40 , a hurricane strap  58  can be placed across the roof  28  and connected to the foundation  4 , in an alternative embodiment of the invention. A hurricane strap  58  may be made of a wide variety of materials, but is preferably a thin strap of about 18 or 22 gauge steel.  
         [0046]    The ridge detail in FIG. 17 shows a roof angle of about 14° from the horizontal (or a 4 to 1 ratio vertical to horizontal). However, the roof angle may be varied from a flat roof to one with a steep pitch.  
         [0047]    In another preferred embodiment of the invention, some or all of the wall panels  20  may be joined at their vertical joints  24  with splines  42 . Accordingly, where all panels  20  in the framework-free building system of the present invention are joined at their vertical joints  24  with splines  42 , every panel of the plurality of panels is juxtaposed and connected via a spline  42 , such as a foam spline, to two panels  20 . Specific spline  42  connections are shown in FIGS. 9, 10,  11  and  12 . For example, foam panels  20  having grooves are juxtaposed and connected via a foam spline  42  located in the grooves of juxtaposed panels to create a plurality of walls and a roof. In one embodiment of the present invention, at least one panel  20  has grooves along each of its two opposing edges  24  so that the said at least one panel  20  is juxtaposed and connected via a foam spline to two other panels  20 . The shape of the splines  42  may vary greatly, but a spline preferably has a rectangular cross-section and extends most of the length of a panel  20 . FIG. 9 is a cross-sectional view of FIG. 1 at A, showing a spline  42  with the cross-sectional dimensions of about 1.5 inches by about 3.5 inches. FIG. 10 shows a cross-sectional view of FIG. 1 at B, where a spline  42  helps connect a wall panel  20  at a corner  48  of the house  2 . The spline  42  connects the vertical side or edge  24  of one panel  20  with a side  46  of another panel  20 , a corner panel. FIGS. 11 and 12 show alternative embodiments of the invention where three wall panels  20  are joined together. Splines  42  may be used to join one or more of the three wall panels  20  together. Further, the outline of splines  42  joining roof panels  20  is shown in FIGS. 16 and 17. Still further, where at least one panel  20  has grooves along each of its two opposing edges  24  to allow it to be juxtaposed and connected via a spline  42  to two other panels  20 , one or both of the two other panels  20  can selected from the group consisting of a corner panel which has a groove along its side  46  (FIG. 10), an interior wall panel that has a groove along its side  46  (FIG. 12), a panel which has a groove along its edge  24  (FIGS. 9 and 11) and a panel which has a groove along each of its two opposing edges  24 .  
         [0048]    After the walls  6  and roof  28  are constructed, openings for doors, windows, electrical outlets and other features are cut into the foam  20 . As seen in a cross-section detail in FIG. 1 at A, the entire structure  2  is coated inside and out with a cementitious material  50  that forms a load-bearing shell  52  that sticks directly to the foam panels  20 .  
         [0049]    In other preferred embodiments, architectural details are added to the house  2  such as texture, color, decorative tile or brick, or architectural features that provide the house  2  with contours. Foam trim panels  20 , for example may be placed at the corners  48  of the house  2  and around doors and windows to provide architectural contours. Architectural features of great variety may be achieved.  
         [0050]    The preferred method of this invention is a new method for constructing a building system  2  without steel or other support systems. Erecting the building system  2  involves first preparing a house site. Traditional methods of site preparation are well-known to those skilled in the art and include leveling of the ground, as well as soil testing. Soil conditions vary significantly such that a geotechnical report is preferably prepared prior to house  2  construction; this involves boring into the soil to a depth of about 10 feet and taking soil samples. Geotechnical tests performed on the soil typically determine compaction and expansion rates for the soil, thus helping to determine house foundation requirements.  
         [0051]    Compacted fill is preferably placed on the site to provide a partial vapor barrier between the foundation  4  and the earth. A concrete foundation  4  is then prepared, which is preferably a traditional concrete slab  4 . In the preferred embodiment, a trench  10  is dug around the perimeter  8  of the foundation  4  and under the interior walls  6  of the house  2 . Referring to FIGS. 3 and 4, cross-sections of the trenches  10  from FIG. 2 are shown across the lines A-A and B-B respectively. Preferably, the trenches  10  are about 4 inches deep, but their depth may be varied greatly. After the trenches  10  are dug, welded wire fabric or reinforced steel  9  is laid on the site. In the most preferred embodiment, welded wire fabric  9  is laid across the foundation  4  area and bent into the perimeter trenches  10 . The wire mesh  9  is preferably No. 6 size wire mesh  9  which has wires perpendicular to each other at 6 inch intervals. Ready-mix concrete is preferably poured into the foundation  4 , vibrated into place, and floated smooth, as is well-known to those skilled in the art.  
         [0052]    In an alternative embodiment, a system of I-beams is laid on the foundation  4  around the perimeter  8  of the house  2  as well as under the interior walls  6 . Additional beams may also be placed. Once the beams are placed, concrete is poured over them to create a foundation  4 .  
         [0053]    In the preferred embodiment, the concrete slab  4  is poured to a depth of 2 inches, except where the trenches  10  exist. The trenches  10  preferably have a total depth of about 6 inches. The slab  4  in the preferred embodiment of a small house  2  is about 24 feet by 20 feet.  
         [0054]    Once the foundation  4  has cured, the pre-cut and numbered foam panels  20  are assembled. In one alternative embodiment of the invention, a bottom track  7  is placed on the foundation  4  along the perimeter  8  of the house  2 . The bottom track  7  is preferably the same width and diameter as the foam  20  and can be flat or have edges on each side to provide a C-shaped track. The track  7  is preferably glued to the foundation  4 . Alternatively, it may be attached with anchor bolts or ramsetted nails. After the bottom tracks  7  are attached, the walls  6  are erected one by one. First, the panels  20  for each wall  6  are joined together, preferably by glue. If a spline  42  is used in the joints  24  between wall panels  20  (as described above), the splines  42  are inserted between the consecutive wall panels  20 . Preferably, the splines  42  are made of foam, for example, EPS foam. In one preferred embodiment, the splines  42  and panels  20  are adhered together with a foam adhesive aerosol spray such as Enerfoam®. Once a wall  6  is constructed, it is set onto the bottom track  7 , if one is used, and erected using temporary bracing, which bracing is well-known to those skilled in the art. Once the outer walls  6  are erected, the interior walls  6  are erected. After all the walls  6  of the house  2  are assembled and temporarily braced, the roof  28  is assembled. The roof panels  20  are pre-cut and numbered for ease of assembly. In the preferred embodiment, the roof panels  20  are glued together one-by-one on top of the house  2 . Preferably, glue such as Enerfoam® is used to help adhere the roof panels  20  to the walls  6  where they meet at the sides  16 ,  18  of the house  2  and at the apex  34  of the roof  28 . Modest temporary bracing, as is well-known to those skilled in the art, is placed under the roof panels  20 .  
         [0055]    Holes are cut in the walls  6  of the house  2  for doors, windows, electrical circuits, plumbing, and as otherwise needed. In one embodiment, wood frames constructed preferably of 2×4&#39;s are installed around the openings for the doors and windows. Openings for windows and other items are then covered with plastic, and then a cementitious material  50  that sticks directly to the foam  20  is sprayed onto the house  2 . The cementitious material  50  is prepared in the preferred method by mixing together water, sand, lime, marble particles, Portland cement, fibers, and an adhesive additive. In the most preferred method, about 2 gallons of water is mixed with about 100 pounds of sand. Then, about 2 gallons of water and about 100 pounds of sand are added and mixed. Then, about 60 pounds of marble particles and about 10 pounds of lime are mixed in, followed by about 1 gallon of water and about 94 pounds of Portland cement. Then, about 0.5 pounds of quarter-inch fibers is mixed in, followed by about 1 gallon of water and about two gallons of acrylic latex. Other additives may be mixed in to improve the cement properties, such as a retarder. Further, up to about two more gallons of water may be mixed into the cement, depending on the heat, humidity and viscosity of the cement mix. The sand used in the process is preferably a blend of number three and four sands (about 50% of each) which may be commonly obtained (e.g., Specialty Sand, Houston, Tex.). The lime and marble particles are available from suppliers such as General Terrazo in Houston, Tex. The marble is preferably in particles similar in size to number one size sand. Type one Portland cement is preferably used and can be obtained from concrete companies or hardware stores such as Home Depot. The fibers used are preferably quarter-inch fibrillated polypropylene fibers (Fibermesh, Synthetic Industries, Houston, Tex.). However, the fibers may be made of many materials including fiberglass or other plastics, or metal.  
         [0056]    In another embodiment, the cement mixture  50  is comprised of approximately 200 pounds of Masonry sand which is a blend of number three and four sands (about 50% of each); approximately 94 pounds of Type one Portland cement; about 5 gallons of water; approximately 1.5 gallons of MICROGEL™; and about ½ pound quarter-inch fibrillated polypropylene fibers.  
         [0057]    This cement mixture  50  is preferably mixed in the mixer of the machine that sprays the cement  50  onto the house  2 . In the preferred embodiment, the spraying machine is a mixer/pump such as the Putzmeister P11S Vario Worm Pump (Germany). Other machines that may be used to mix and spray the cementitious coating  50  include the Spray Force® drywall and plastering machine, model Hurricane 350 (Spray Force Manufacturing, Inc., Fresno, Calif.) or the Allentown Powercreter® (Master Builders, Inc., Cleveland, Ohio or Allentown Co., Allentown, Pa.).  
         [0058]    The spraying machine has a rubber hydraulic hose (available from Putzmeister) attached to its output that is preferably about 75 feet long. The first approximately 25 feet of the hose has about a 3 inch diameter, the second approximately 25 feet of hose has about a 2 inch diameter; and the last approximately 25 feet of hose has about a 1.5 inch diameter. An adjustable nozzle, such as the type used for stucco or gunnite, is attached to the end of the hose. It preferably has a {fraction (3/16)} inch to a ¾ inch variable tip diameter. In addition, an air hose is attached from the spray machine to the nozzle to provide air entrainment into the cement mix  50  as it blows from the nozzle, as is well-known to those skilled in the art. By trial and error, the air pressure and the nozzle tip size are adjusted. Preferably, a nozzle tip size of ⅜ inch is used with about 50 psi of air pressure when the air temperature is 95°; about 45 psi of air at 80°; and about 40 psi at 75°.  
         [0059]    Before the cement  50  is mixed in the spray machine, a primer mixture is made and pumped into the hose. The primer is comprised of about 60 lbs. of lime and about 4 gallons of water, which is mixed for about 3 minutes or until complete mixing occurs. Once the sprayable cement mixture  50  is ready to spray onto the house  2 , the primer is pumped into buckets for reuse. Then, the cement mixture  50  is sprayed onto the house  2  in a thin coating  54 , as shown in FIG  1 A. A single coating  54  in the range of about ¼ inch to about ¾ inch is preferably applied. In the most preferred embodiment, two thin coatings  54  are applied. The first coating  54  is applied to a thickness of about ¼ inch and allowed to cure for about 30 minutes or until a permanent set occurs. Then, a second coating  54  is sprayed on to a thickness of about ¼ inch. The house  2  then cures and attains its final compressive strength as a load-bearing shell  52  around the underlying house materials. In an alternative embodiment, the cement coating  54  is applied by troweling or other non-spray methods. Temporary bracing of the walls  6  and roof  28  is removed once the coating  52  has cured for about three days.  
         [0060]    Before the coating  54  dries, it may be decorated by etching patterns into it; by pressing rocks or other appliques into it; by troweling the surface smooth, and by many other decorative techniques. Alternatively, after the cement  54  dries, appliques may be screwed into the cement  54 . After the house  2  has cured for about five days, it may be painted or further water sealed. An elastomeric paint such as Hydrostop® accomplishes both water sealing and provides color to the house  2 . The paint or sealant is preferably applied by rolling, airless paint gun, or paint brush. In another preferred embodiment of the method, powdered dyes are added to the cementitious material  50  when it is being mixed so that the sprayed cementitious material  50  is in a preferred color, thus obviating any need for painting thereafter.  
         [0061]    Before the cementitious material  50  is applied, architectural details can easily be added to the structure around windows, doors, eaves, corners and in other areas by applying additional foam pieces  20  to the walls  6 . Such architectural foam pieces  20  may be tooth-picked or glued into place as described above.  
         [0062]    In another preferred embodiment of the invention, an approximately 1 inch by 4 inch wooden strip is attached along the side of the concrete foundation  4 . This provides a ledge  56 , preferably made of wood, above which the cementitious material  50  is sprayed. The strip is elevated above the ground surface so that shifting ground does not touch the cementitious coating  52 . In another alternative embodiment, the foam panels  20  are inset about one inch from the edge of the concrete foundation  4  creating a ledge above which the cementitious material  50  may be sprayed. The cementitious material  50  is then sprayed on the wall panels  20 , but not over the concrete foundation  4 .  
         [0063]    Although the description of the preferred invention is directed to a small house, the building system may be used in many applications. For example, the building system may be used for sheds, barns, boat houses, large houses and commercial buildings.  
         [0064]    Common engineering elements such as pumps, gages, valves, controllers, material selection and the like are not shown or described except when necessary for the understanding of the invention, since for the most part, selection and placement of such equipment is well within the skill of the ordinary engineer. Although the above method and apparatus are described in terms of the above preferred embodiments, those skilled in the art will recognize that changes in the process and apparatus may be made without departing from the spirit of the invention. Such changes are intended to fall within the scope of the following claims.