WO1995009952A1

WO1995009952A1 - Method for constructing a monolithic structure

Info

Publication number: WO1995009952A1
Application number: PCT/US1994/011477
Authority: WO
Inventors: James B. Korndorffer; Gregory J. Miller
Original assignee: Korndorffer James B; Miller Gregory J
Priority date: 1993-10-04
Filing date: 1994-10-04
Publication date: 1995-04-13
Also published as: AU7973294A

Abstract

A method for constructing a monolithic structure from composite panels (10) and a hardenable material (32). Composite panels (10) are positioned in a substantially vertical position to form a peripheral wall around an interior space (24). Each panel (10) is formed by the combination of an expanded foam (14) and a wallboard material (16) bonded to at least one side of the panel (10). The interior surface (20) of the peripheral wall (18) is covered by the wallboard material (16) to provide a finish surface. Composite roof panels (38) are positioned over the peripheral wall (18), wall to shelter the interior space (24). Each roof panel (38) can be formed with a wallboard material (16) and a waterproof material (40) bonded to opposite sides of an expanded foam core (14). A hardenable material (32) is formed on the exterior surface (22) of the peripheral wall (18) for connecting the composite panels (10) and for connecting the roof panels (38) to the peripheral (18).

Description

METHOD FOR CONSTRUCTING A MONOLITHIC STRUCTURE

Background of the Invention The present inv ntion relates to a method for constructing a monolithic structure. More particularly, the invention relates to a method of constructing a monolithic structure from composite panels formed from the combination of expanded foam and a wallboard material.

A significant amount of effort has been exerted to improve the design and construction of structures such as residential houses. In particular, many concepts have been developed to increase building strength and to reduce the construction cost of such structures. Existing concepts generally can be classified within several broad categories. One group of concepts assembles preformed panels into a structure by connecting the panels together. The joints between the panels are then sealed. Another group of concepts create a monolithic structure by spraying concrete or similar materials placed a form. As described below, these concepts have inherent limitations that increase the overall cost for structures constructed by such technigues.

Prefabricated panels are frequently incorporated into structures as a technique for reducing construction costs. Prefabricated panels can be formed in a controlled factory environment to improve the quality of the product and to produce the panels at assembly line production rates. The panels are then transported to the construction site and are assembled into the structural frame. For example, United States Patent No. 3,707,165 to Stahl discloses a plumbing wall module that encapsulates plumbing components within a foam core. In addition. United States Patent No. 3,775,240 to Harvey illustrates a process for pouring concrete into horizontal forms shaped as building panels. The concrete panels are then cured and are erected into a vertical position to form a structure.

If the contractor desires to reduce transportation costs, prefabricated panels can be formed at the construction site after the foundation for the structure has been poured, and can be lifted into vertical alignment after the concrete has set. This type of construction, commonly referred to as "tilt wall" construction, is frequently used in the construction of large, single story structures such as in warehouses and is rarely used in multistory or residential structures.

Prefabricated panels and tilt wall panels are typically fastened by welding steel ties embedded in the panels. The seams between panels on the exterior of the structure are covered with masonry, stucco, or similar coverings, and the interior seams are covered with insulation and wallboard materials such as sheetrock. Many techniques have been developed to cover the interior seams between the interior faces of the panels. For example,

United States Patent No. 4,970,838 to Phillips shows wood furring strips fastened to the panel. Wallboard such as sheetrock is then nailed, glued, or otherwise fastened to the wood furring strips. Alternatively, the wall covering material can be fastened to the panels with adhesives. A significant amount of labor is necessary to perform these steps, and all of the labor is necessarily performed in the field.

Labor intensive construction techniques to finish the interiors of structures inevitably add expense to the construction of .such structures. For many structures, labor typically costs fifty percent of the total construction cost. Labor expenses are increased in remote areas, when construction workers commute to the construction site or are required to reside at the construction site. Accordingly, there is a clear need for construction techniques that reduce the labor cost of constructing structures.

To reduce the cost of constructing structures, various techniques have been developed to create monolithic structures. These structures are typically created by covering a form with a cementitious material such as gunite or shotcrete. As shown by United States Patent No. 4,678,157 to Fondiller, elastic forms can be inflated to provide a temporary form backing for the structure. Concrete and other materials can be sprayed over the forms to create the structure, and the forms can be deflated or otherwise removed after the concrete sets. Another technique is illustrated in United States Patent No. 4,253,288 to Chun, wherein panels are erected and are sprayed with insulating material to integrate the panels.

Stucco is applied to the exterior wall surface, and plaster is applied to the inner wall surfaces to complete the monolithic structure form. Other construction techniques use detachable steel forms that can be erected to form a base for a concrete structure.

Monolithic structures do not contain seams similar to those created by prefabricated panels, yet monolithic structures have unfinished .interior walls without the wall finishes conventionally used for inhabited structures. Accordingly, wood furring strips and other conventional techniques are used to fasten wall covering material such as sheetrock to the- monolithic concrete walls. Significant labor is required to finish the interior walls and ceilings of a monolithic structure, and this additional labor inevitably increases the construction cost of such structures. For many structures, labor typically costs fifty percent of the total construction cost. Labor expenses are increased in remote areas, when construction workers commute to. the construction site or are required to reside at the construction site. Additionally, the extra labor necessary to finish a structure inherently delays the overall construction time, and this delay further increases construction costs.

Accordingly, a need exists for an improved method that permits the efficient construction of structures. The method should reduce the labor necessary to construct the structure and should expedite the overall construction schedule for the structure.

Summary of the Invention The present invention overcomes the disadvantages of the prior art by furnishing an efficient method for constructing a monolithic structure. The method is practiced by positioning a first panel in a substantially vertical position, wherein the panel is formed by the combination of an expanded foam and a wallboard material located on at least one vertical face of the panel.

Additional panels are positioned in cooperation with the first panel to form a peripheral, wall having an interior surface and an exterior surface. The panels are positioned so that the wallboard material is located on the interior surface of the peripheral wall, and a hardenable material is formed on the exterior surface of the peripheral wall. In other- embodiments of the invention, a roof can be connected to the peripheral wall, and the roof can be constructed from panels formed with expanded foam bonded to a wallboard material. In addition, the structure can be constructed on a foundation, and the panels for forming the structure can be formed at a location proximate to the foundation. An interior panel can be positioned within the interior of the peripheral wall,. and the interior panel can be formed with a wallboard material bonded to each vertical surface of the interior panel. Because the composite panels are formed with a wallboard material having a finish surface, the joints between adjacent panels is easily finished with conventional finishing techniques.

Brief Description of the Drawings

Figure 1 illustrates an elevation view of a composite panel in a substantially vertical position on a foundation.

Figure 2 illustrates an elevation view of a plurality of panels positioned to form a peripheral wall around an interior space, and further shows an interior wall positioned within the peripheral wall.

Figure 3 illustrates an elevation view showing composite roof panels attached to a peripheral wall, and further illustrates the application of a hardenable material to the exterior wall of the peripheral wall.

Figure 4 illustrates a schematic view showing the connection between a composite roof panel and the top of the peripheral wall.

Description of the Preferred Embodiments

Figure 1 illustrates composite panel 10 positioned in a substantially vertical orientation on foundation 12. Foundation 12 is- not necessary to the construction process, but can be incorporated to provide stability and consistency for the finished structure. Panel 10 is a composite formed from expanded foam 14 that is bonded to a finish wallboard material 16. In a preferred embodiment of the invention, this bonding is accomplished in a mold (not shown) by placing wallboard material 16 in the mold and by injecting expanded foam 14 into the mold. This feature is significant because the injection of foam 14 under high pressure into the restrained substructure of the panel shape causes the injected foam core to transition from a liquid to a closed cell foam core. This foam core is securely and permanently bonded to all panel components contacted by foam 14. Consequently, the high pressure injection of foam 14 into panel 10 creates a composite panel that attenuates sound, that furnishes good thermal insulation properties, and provides a strong structural connection.

Wallboard material 16 can comprise various materials selected for the desired properties. Although wallboard material 16 comprises sheetrock in a preferred embodiment, wallboard material 16 can also comprise marlite, masonite, teflon or other synthetic materials, glass such as found in mirrors, sheet metal such as aluminum or steel, and other materials. Preferably, wallboard material 16 comprises a material resistant to fire.

Figure 2 illustrates a plurality of panels 10 positioned in a substantially vertical position on foundation 12. Panels 10 form a peripheral wall 18 having interior surface 20 and exterior surface 22. Interior surface 20 for each panel 10 comprises wallboard material 16. Peripheral wall 18 encloses an interior space 24 that defines the living space of the structure. Interior panel 26 is positioned in a substantially vertical position to subdivide interior space 24, and is supported with conventional fastening techniques.

In a preferred embodiment of the invention, each vertical surface of interior panel 26 comprises a wallboard material 16 bonded to expanded foam 14. Foam 14 furnishes insulation value, known as the resistance to thermal transfer (R-value) , for panel 10. The R-value of panel 10 depends on the material used for foam 14 and on the thickness of foam 14. For example, polyurethane foam yields an R-value of approximately seven and one half per inch of foam, so that a six inch panel would have an R-value rating of approximately 45.

The density of a low density polyurethane foam typically approximates two pounds per cubic foot. This fact will affect the ability of panel 10 to carry structural loads and to resist bending moments. Available Class 1 urethane products carry an Underwriters Laboratory rating of UL-723 and do not produce CFC gases as the foam degrades.

As shown in figure 2, openings such as door 28 and window 30 can be located in panels 10. Because of the unique composition of panels 10, openings 28 and 30 can be formed in panels 10 during the manufacture processes, or can be later cut into panels 10 with conventional rotary or reciprocating saw techniques.

Exterior surface 22 can be protected by forming a hardenable material 32 on exterior surface 22. In one embodiment of the invention, hardenable material 32 can comprise a cementitious material such as gunite. Hardenable material 32 simultaneously bonds panels 10 together and furnishes a protective covering for exterior surface 22. Steel or synthetic mesh 34 can be fastened to exterior surface 22 to strengthen hardenable material 32 and the connections between panels 10. Hardenable material 22 can be formed on exterior surface 22 in many different ways such as be spraying or by troweling techniques. While the thickness and composition of the dry hardenable material 32 provides structural strength for the structure, hardenable material 32 is also desirable because the aesthetic character of the structure can be modified by forming a texture in hardenable material 32.

Composite panel 10 is stronger, more rigid, and more resistant to fire than panels formed from other material, or using other combinations of the same materials. Although expanded foam is used in the manufacture of prefabricated panels, expanded foam is flammable and fails when exposes to the open flame of a fire. Flame resistant wallboard material 16 on interior surface 20 of panel 10 protects foam 14 from fire, and thus increases the fire rating of a structure constructed from panels such as panel 10. As previously stated, wallboard material 16 can comprise sheetrock, also known as gypsu board, that is commonly used to increase the fire rating of the walls in structures. As known in the art, the thickness of the sheetrock controls the fire rating of the material.

In addition to the improved fore resistance provided by composite panel 10, such unique design permits the support of structural loads such as the forces exerted by roof loads. Foam 14 is capable of supporting certain structural loads, in compression, depending on the thickness and height of panel 10. Wallboard material 16 in combination with foam 14 provides additional load supporting capability in compression. However, the load bearing capability of foam 14 and wallboard material 16 declines dramatically when compressive loading forces begin to bend the panel formed with foam 14 and wallboard material 16. When bending of panel 10 begins, the downward compressive forces are transformed into a combination of compressive forces and lateral shearing forces. Because many materials potentially used for wallboard material 16 are relatively weak when exposes to shearing forces, any bending forces acting on panel 10 will accelerate structural failure of panel 10.

To reduce the possibility of failure due to structural bending, studs (not shown) can be positioned within panel 10 to add rigidity and compressive strength to panel 10. Alternatively, hardenable material 32 provides structural compressive strength for peripheral wall 18 of the structure. Such strength can be enhanced by increasing the thickness of hardenable material 32, and by selectively creating thicker sections of hardenable material 32 that are reinforced with steel or mesh in a manner similar to that found in the grade beams of concrete foundations.

Figure 3 illustrates a different embodiment of the invention wherein roof 36 is connected to peripheral wall 18. As shown, roof 36 is formed with roof panels 38 bearing on peripheral wall 18 and connected at apex 40 of roof 36. Although roof 36 can be constructed with conventional materials and techniques, one embodiment of the present invention contemplates that roof panels 38 can be formed as composite panels- similar to panels 10. In one embodiment, illustrated in figure 4, roof panels 38 can be formed by expanded foam 14 bonded to roof covering 40. Roof covering 40 can comprise a natural or synthetic material typically used as a roofing material, and will bond to expanded foam 14 because of the unique properties of expanded foam 14. For example, roof covering 40 can comprise a Spanish style composite tile, a conventional natural or synthetic shingle, or similar product.

In another embodiment of the invention, expanded foam 14 can be bonded to wallboard material 16 to furnish a finish surface facing interior space 24. This embodiment of the invention would be appropriate in applications where the structure comprised a cathedral ceiling in interior space 24.

As shown in Figure 4, roof panels 38 are connected to peripheral wall 18 with structural ties or anchors 44. Alternatively, other fastening systems could be used to anchor roof panels 38 to peripheral wall 18. In a preferred embodiment of the invention, hardenable material 32 is formed on soffit surface 46 to furnish a structural connection between roof panels 38 and peripheral wall 18. In another embodiment of the invention, hardenable material 32 can be formed on fascia surface 48 of roof panel 38 to protect fascia surface 48 from environmental conditions.

Finished panel 10 can readily be incorporated into a structure without additional preparation. The ease and speed of manufacture presents an opportunity for panels to be fabricated near the construction site and immediately moved into position within the structure. This feature permits construction efficiencies by eliminating the need for the transportation of large prefabricated panels over great distances. In addition, this feature permits the panels to be fabricated in large units equal to the size of the finish walls, thereby reducing the number of joints between adjacent panels. The finished panel can be fabricated within close tolerances and will provide straight, uniform walls for the finished structure.

The present invention is particularly useful because the installation technique of prefinished panels presents a finished surface that requires a minimum amount of finish work. Instead of the time consuming responsibilities typically associated with taping and floating finish sheetrock walls, including the elimination of joints and nail holes associated with sheetrock, the finish work can be quickly completed within days instead of weeks. This reduction in finish work time results in significant direct labor costs and accelerates the overall construction schedule for the structure. This accelerated construction schedule reduces the indirect costs associated with interim financing of construction and maximizes the overall efficiency of the construction processes.

The present invention is also useful because it provides a system for permitting the construction of structures without wood framing members. The elimination of wood structural components is particularly important as timber prices increase due to environmental concerns, and is also preferable because the composite panels and the exterior surface formed from a hardenable material have a higher resistance to penetration by insects. The hardenable material also forms an exterior surface that resists degradation or structural failure caused by environmental forces. Consequently, the present invention provides a method for constructing structures that will increase the life expectancy of the structure.

Although the present invention has been described in terms of certain preferred embodiments, it will be apparent to those of ordinary skill in the art that various modifications can be made to the inventive concepts without departing from the scope of the inventive concepts. The embodiments shown herein are merely illustrative of the inventive concepts and should not be interpreted as limiting the scope of the inventive concepts.

Claims

What is claimed is:

1. A method for constructing a monolithic structure, comprising the steps of: positioning a first panel in a substantially vertical position, wherein said panel is formed by the combination of an expanded foam and a wallboard material located on at least one vertical face of said panel; positioning additional panels in cooperation with said first panel to form a peripheral wall having an interior surface and an exterior surface, wherein said interior surface comprises a wallboard material bonded to each panel; and forming a hardenable material on said exterior surface of said peripheral wall for connecting said panels.

2. A method as recited in Claim 1, further comprising the step of reinforcing the hardenable material.

3. A method as recited in Claim 1, further comprising the step of shaping the hardenable material.

4. A method as recited in Claim 1, further comprising the step of positioning a panel interior of said peripheral wall in a substantially vertical orientation, wherein said interior panel is formed by the combination of an expanded foam and a wallboard material bonded to said foam on each vertical face of said panel.

5. A method as recited in Claim 1, further comprising the step of finishing the interior surface of said peripheral wall by treating the joints formed between adjacent panels.

6. A method as recited in Claim 1, further comprising the step of connecting a roof to said peripheral wall.

7. A method as recited in Claim 1, further comprising the step of connection a plurality of roof panels to said peripheral wall for the purpose of sheltering the interior space formed by said peripheral wall.

8. A method as recited in Claim 7, further comprising the step of forming a hardenable material to connect said roof panels to said peripheral wall.

9. A method as recited in Claim 7 wherein each roof panel is formed by the combination of an expanded foam and a wallboard material bonded to a surface of the expanded foam, further comprising the step of positioning each roof panel so that said wallboard material faces the interior space defined by said peripheral wall and said roof panels.

10. A method as recited in Claim 9, further comprising the step of finishing the surface of wallboard material by treating the joints between adjacent roof panels.

11. A method for constructing a monolithic structure on a foundation, comprising the steps of: forming a plurality of panels proximate to the foundation of the structure, wherein each panel is formed by the combination of an expanded foam and a wallboard material located on at least one surface of such panel; positioning said panels in a substantially vertical position on the foundation; connecting said panels to form a peripheral wall having an interior surface and an exterior surface, wherein said wallboard material on each panel is located on the interior surface of said peripheral wall; and forming a hardenable material on said exterior surface of the peripheral wall.

12. A method as recited in Claim 11, further comprising the step of transporting the equipment for forming said panels to a location proximate to the foundation of the structure.

13. A method as recited in Claim 11, further comprising the step of positioning a panel interior of said peripheral wall in a substantially vertical orientation, wherein said interior panel is formed by the combination of an expanded foam and a wallboard material bonded to said foam on each vertical surface of said panel.

14. A method as recited in Claim 13, further comprising the step of forming said interior panel proximate to the foundation of said structure by bonding said wallboard material to said expanded foam.

15. A method as recited in Claim 11, further comprising the step of finishing the interior surface of said peripheral wall by treating the joints formed between adjacent panels.

16. A method as recited in Claim 11, further comprising the step of connecting a roof to said peripheral wall.

17. A method as recited in Claim 11, further comprising the step of connecting a plurality of roof panels to said peripheral wall for the purpose of sheltering the interior space formed by said peripheral wall.

18. A method as recited in Claim 17, further comprising the step of forming said roof panels at a location proximate to the foundation of the structure by the combination of an expanded foam and a wallboard material bonded to a surface of each roof panel.

19. A method as recited in Claim 18, further comprising the step of finishing the surface of wallboard material on said roof panels by treating the joints between adjacent roof panels.

20. A method as recited in Claim 17, further comprising the step of forming a hardenable material to connect said roof panels to said peripheral wall.