A foam core cement construction panel having shear members and lateral rails that form a channel-beam-like structure and novel methods of using the panels to form an integrated roof structure that serves three separate functions: (1) the roof load structure assembly; (2) the roof's exterior waterproof assembly; and (3) the roof's exposed interior ceiling assembly and which can include internal hydronics for added climate control.

BACKGROUND 
     The present invention relates to building construction members, with particular emphasis on methods and apparatus for construction of a building roof system and, in particular, to methods and apparatus for constructing a roof system that integrates multiple roof functions into a single roof assembly. 
     A building roof system typically performs three separate functions through three separate assemblies: (1) the roof load structure assembly which is typically composed of trusses, rafters, or purlins and plywood sheathing; (2) the roofs exterior waterproof assembly which is typically composed of building paper overlaid by tile, composition shingles or metal; and (3) the roofs exposed interior ceiling assembly which is typically composed of drywall, wood, plaster or the like. 
     The present invention teaches a novel construction panel and a roof system using that panel and methods of constructing such a roof system that performs all three of the aforementioned roof functions by a single integrated roof assembly and, in addition, is capable of integrating and performing the building's heating and cooling functions which are typically provided by a HVAC system or radiant slab. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The present invention teaches a novel construction panel having a stress skin concrete structure in which two thin leaves (of the order of 1½″) of concrete are cast over a reinforced polystyrene slab. The TRI-D HADRIAN® foam panel is one product that can be used for this purpose. The panel of the invention has the advantageous structural qualities of a channel beam, an upper surface that serves as an all-weather roof covering, a lower surface that serves as an interior ceiling. In one embodiment, the building heating and cooling is provided by embedded hydronic tubing that can, by the circulation of fluids, capture solar heat and use it to provide heating, cooling or both and provide active thermal control by shifting peak demands for energy and reduce energy usage. A typical panel, by way of example only, is 4 feet wide and has an overall thickness of 3″ plus the thickness of the polystyrene panel (from 3″ to 6″). Each panel can be cast to a length up to about 40 feet. These novel construction panels are assembled together by a novel method that creates a single roof diaphragm that is weatherproof, thermally efficient, and able to span significant distances without intermediate support. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partially exploded isometric view showing a building with a roof system of the present invention; 
         FIG. 2  is a side sectional view of a construction panel of the present invention taken along the line  2 - 2  of  FIG. 4 ; 
         FIG. 3  is a top left isometric view of one end section of the construction panel of the invention revealing internal metal reinforcing members; 
         FIG. 4  is a top right isometric view of the construction panel of the invention; 
         FIG. 5  is a top left isometric view of one end of the construction panel of the invention; 
         FIG. 6  is a bottom right isometric view of the construction panel of the invention; 
         FIG. 7  is a partial side elevation of a rail of the construction panel of the invention showing a shear key recess; 
         FIG. 8  is a sectional view taken along the line  8 - 8  of  FIG. 7 ; 
         FIG. 9A  is sectional view taken along the line  9 - 9  of  FIG. 10  before a bolt and grout are added; 
         FIG. 9B  is the same as  9 A illustrating the addition of a fastener and grout and an exploded view of a weather cap; 
         FIG. 9C  is the same as  9 B with the weather cap in place; 
         FIG. 10  is a partial top plan view illustrating the junction between side-by-side construction panels of the invention; 
         FIG. 11B  is a partial plan view of two adjacent anchor bolt cutouts forming an anchor bolt channel at a bond beam; 
         FIG. 11A  is a sectional view taken along the line  11 A- 11 A of  FIG. 11B ; 
         FIG. 12  is a partial side elevation view illustrating the junction of a construction panel of the invention and a bond beam (which is in section); 
         FIG. 13  is a top right isometric view of a construction panel of the invention configured to attach to the rake bond beam; 
         FIG. 14  is a sectional view taken along the line  14 - 14  of  FIG. 13 ; 
         FIG. 15  is a partial side view of two construction panels of the invention at the ridge beam (shown in cross-section); 
         FIG. 16  is the same as  FIG. 15  with a channel keystone added (shown in section); 
         FIG. 17  is the same as  FIG. 16  with a superstructure added; 
         FIG. 18  is a semi-schematic side view of a hydronic system added to the construction panels of the invention; and 
         FIG. 19  is a schematic plan view of a hydronic system added to a construction panel of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , a plurality of construction panels  11 , according to the present invention, are assembled together, as described in detail below, to form a continuous diaphragm, seismic-resistant roof structure  12  for a building  13  having generally parallel, spaced-apart walls  18  capped by bond beams  19  and end walls  20  capped by rake beams  25 . The roof structure  12  is capable of performing all of the functions of: (1) the roof load structure assembly which is typically composed of trusses, rafters, or purlins and plywood sheathing; (2) the roof's exterior waterproof assembly which is typically composed of building paper overlaid by tile, composition shingles or metal; and (3) the roof's exposed interior ceiling assembly which is typically composed of sheetrock, wood or plaster. The present invention is also capable of providing the heating and cooling system needs. 
     A ridge beam  14 , trusses  16  and truss ties  17 , typically essential components of a roof structure, are, in the present invention, shoring for the assembly of the roof structure  12  of the present invention and can either be removed after assembly or left in place as redundant structure. 
     Referring to  FIGS. 2-6 , a generally rectangular construction panel  11  of the present invention has lateral panel edges  21  and  22 , panel end edges  23  and  24 , a generally rectangular foam (styrene) slab  26  having a slab upper surface  27 , a slab lower surface  28 , a slab end edge  29 , and a slab end edge  30  is disposed between the panel end edges  23  and  24  and panel side edges  21  and  22 . The foam slab  26  has a mesh frame  31  overlaying the slab upper surface  27  and a mesh frame  32  overlaying the lower surface  28 . The mesh frames  31  and  32  are advantageously connected by diagonal truss wires  33 . 
     A concrete panel bed  36  having an exterior exposed panel bed surface  36   a  is formed over and covers the upper surface  27  of slab  26  and includes mesh frame  31 . A concrete panel floor  37  having an exterior exposed panel floor surface  37   a  is formed over and covers the lower surface  28  of slab  26 , including mesh frame  32 . The panel bed  36  extends beyond end edge  24 , creating a cantilever section  39 . 
     The panel bed  36  and its exposed surface  36   a  are, in the constructed roof  12  of the present invention, both a component in the roof structure and the weather surface, requiring no additional weatherproofing materials. In this regard, the concrete used to form bed  36  and all other concrete elements of the roof structure  12  exposed to weather can advantageously include any of several known waterproofing ingredients such as Xypex®. 
     A first upstanding concrete rail  41  extends along panel lateral edge  21  and above panel bed  36  and has an exterior sidewall surface  41   a , a slightly canted interior sidewall surface  41   b , and a top surface  41   c . A second concrete rail  43  generally parallel to rail  41  extends along panel lateral edge  22  and above panel bed  36  and has an exterior sidewall surface  43   a , a slightly canted interior sidewall surface  43   b , and a top surface  43   c . Together, the rails  41  and  43  and panel bed  36  form a shallow U-shape indicated at  49  ( FIG. 5 ). The rails  41  and  43  extend the full length of lateral edges  21  and  22 , including the cantilever section  39 , and include steel reinforcing  45  ( FIG. 3 ) in a manner well known to those skilled in the art of reinforcing concrete structures. 
     A first concrete shear member  46  extends between and secures together panel bed  36  and panel floor  37  from lateral edge  21  to lateral edge  22  adjacent slab end edge  29  and defines end edges  23 . A second concrete shear member  47  extends between and secures together panel bed  36  and panel floor  37  from lateral edge  21  to lateral edge  22  adjacent slab end edge  30  and defines end edges  24 . The shear member  47  also includes a support surface  48  (the function of which is described below) between end edge  24  and panel floor surface  37   a  that is at an obtuse angle to both. 
     The shear members  46  and  47  connect panel bed  36  and panel floor  37  and carry the full shear demand on the construction panel  11  and bear the weight of the panel at the ridge beam  14  and at the walls  18  (see  FIG. 1 ). The panels are installed so that they span the entire distance from the bond beams  19  of walls  18  to the ridge beam  14  (which can be 40 feet or more). The strength of the panel  11  is all the greater by virtue of the rails  41  and  43  which with the panel bed  36 , shear members  46  and  47 , and panel floor  37  form a channel structure with the enhanced load-bearing characteristics of such structures. 
     To further reinforce the panel  11  at shear members  46  and  47 , a plurality of reinforcing rods  51  are cast into the panel  11  at spaced-apart locations between lateral panel edges  21  and  22  so as to be disposed within the panel floor  37 , shear members  46  and  47 , and panel bed  36 . For reasons that are explained below, an anchor bolt  52  is cast into shear member  46  from which it protrudes. 
     In one embodiment of the invention all of the concrete members (panel bed  36 , panel floor  37 , rails  41  and  43  and shear members  46  and  47 ) are one integral reinforced (typically with rebar) concrete structure created in a form in a manner known to those skilled in the art. 
     As best seen in  FIGS. 4-8 , a plurality of concrete-framed shear key recesses  53  are formed at set spaced-apart locations in the exterior sidewall surfaces  41   a  and  43   a  of rails  41  and  43 , respectively. The shear key recesses  53  in rail  41  (which is representative of all of the recesses  53 ) extends from rail top surface  41   c  to the foam slab upper surface  27  which includes all of the panel bed  36 . In forming the recess  53 , a portion of the foam slab  26  and its mesh frames  31  and  32  surrounding the recess are cut back and replaced by a concrete frame  55  that surrounds the recess  53 . Each shear key recess  53  is advantageously rectilinear and preferably a generally rectangular parallelepiped. 
     A fastener aperture  54  at each recess extends through the rail into a fastener recess  62  in the opposing interior surface of the rail, permitting a fastener such as a bolt to extend through the rail at the location of the recess  53 . Fastener recesses  62 , which are situated entirely within the interior surface of the rail above the panel bed  36 , receive a bolt head or nut or other fastener component that may be used. The aperture  54  may be formed by a length of tubing  54   a  that remains in place as an aperture lining. 
     As best seen in  FIGS. 9A ,  9 B,  9 C and  10 , when two construction panels  11  are assembled side-by-side with their respective recesses  53  aligned, a shear key pocket  56  is formed. A fastener, such as bolt  57  in fastener apertures  54  secured by nut  58  in fastener recess  62 , secures the two rails together. The shear key pocket  56  is filled with grout, forming a shear key  61 . The shear key  61  is formed in both rails  41  and  43  of the two adjacent panels from their top surfaces  41   c  and  43   c  to the lower surface  27  of foam slab  26 , including the panel bed  36 . The shear keys  61  so formed resist shear forces between construction panels  11  and interlock the individual panels  11  together, creating a diaphragm that distributes wind and seismic loads to the walls  18  ( FIG. 1 ). 
     The tops  41   c  and  43   c  of the joined rails  41  and  43  are covered with either a Spanish cap tile (not shown) or metal flashing  89  (or any other suitable sealing materials) to waterproof the seams between the rails, thus making the overall roof system waterproof. An important feature of the roof structure  12  is that the panels  11  are both the structure and the waterproofing system. Thus, in addition to the structures for sealing the seams between the panels  11 , as described above, the panels  11  are cast with an integral waterproofing compound (such as Xypex®). 
     A plurality of roof panels  11  are assembled together according to the methods of the present invention to create the novel roof structure  12  of the invention. 
     Referring to  FIGS. 5 ,  11 , and  12 , as is typical in building construction, the building side walls  18  are topped by a bond beam  19 . For the purposes of the present invention, the top of the bond beam  19  has a generally horizontal surface  69 , an abutment surface  73  and a cantilever overhang surface  74 . The abutment surface  73  is advantageously at a right angle to the angle of the panel  11 , although other angles could also provide the support required. The cantilever overhang surface  74  is generally parallel to the roof panels  11 . 
     In assembling the roof structure  12 , the end edge  24  of each panel  11  is placed in engagement with, and is supported by, abutment surface  73 . The cantilever section  39  of panel bed  36  is located over the overhang surface  74  of bond beam  19 , and the shear member support surface  48  of shear member  47  rests on, and is supported by, bond beam surface  69 . 
     In addition to the recesses  53  in rails  41  and  43 , each rail includes an open ended anchor bolt cutout  80  (see  FIG. 5 ) that extends from the top surface  43   c  of rail  43  ( 41   c  in the case of rail  41 ) all the way to the panel floor surface  37   a  and from the end edge  24  a distance sufficient to receive an anchor bolt  71  ( FIG. 11B ). Cutouts  80  have a through aperture  85  and an interior fastener recess  86 . When two rails  41  and  43  are placed side-by-side ( FIG. 11B ), the aligned anchor bolt cutouts  80  form an anchor bolt channel  81  that surrounds anchor bolt  71  embedded in the bond beam  19 . Anchor bolts  71  can be pre-cast into the bond beam  19  at specified locations along its length and captured within the anchor bolt channel  81  as the panels are mounted on the bond beam. Alternatively, the anchor bolts can be drilled into the bond beam as the panels are mounted. 
     In either case, once the panels are in place and the anchor bolts  71  in anchor bolt channels  81 , channels  81  are filled with grout  90  ( FIG. 11B ) (the lower open bottom space being temporarily blocked), providing a secure connection between the panel  11  and the bond beam  19 . 
     It will occur to those skilled in the art that geometries other than those described herein could also provide the necessary support functions. What is required is that the wall  18  and bond beam  19  support the loads of the panels  11  and resist movement of the panels  11  in both their longitudinal and lateral directions. 
     Referring to  FIGS. 1 ,  13  and  14 , while all of the panels  11  that are only between the ridge  14  and the bond beam  19  and do not engage the rake beam  25  are substantially the same, a special rake panel  106  is provided at, and secured to, the rake beam  25 . Rake panel  106  has all of the same structure as panel  11  except for the substitution of rail  43  with a rake panel rail  107 . Because rake panel rail  107  does not abut another panel, as do all interior panels  11 , its exterior surface  107   a  has no recesses (such as recesses  53 ) or cutouts (such as panel cutouts  80 ), although the opposing rail  108  has all of those features, as well as all others described in connection with rail  41 . In order to secure panel  106  to the rake beam  25 , concrete framed anchor bolt cups  109  are formed at spaced-apart locations along edge  104  of panel  106  adjacent rail  107 . The open end  105  of cups  109  are at the panel floor surface  111 . 
     Anchor bolts  112  are cast into rake beam  25  at locations that match the locations of cups  109  such that when panel  106  is mounted on the bond beam  19 , ridge beam  14  and rake beam  25 , an anchor bolt  112  is located within a cup  109 . To firmly secure the anchor bolts to the panel  106 , the cup is filled with grout. This is accomplished by inserting the grout into a fill tube  114  that extends from the rail top surface  107   c  into cup  109 . An air release tube  116  follows a parallel path to that of tube  114  and provides an escape for replaced air. 
     It will be obvious to those skilled in the art that the rake panel  106  at one rake will have the special rake rail  107  on the side opposite to the side of the rake panel at the other rake. 
     Referring to  FIGS. 15 ,  16  and  17 , the ridge beam  14  (see also  FIG. 1 ), which can advantageously (but not necessarily) be of reinforced concrete, has upper support surfaces  77  and  78  angled to match the angle of the roof structure  12 . A plurality of ridge beam anchor bolts  79  are cast into the ridge beam  14  at spaced-apart locations along its length. 
     In assembling the roof structure  12 , panels  11  are placed side-by-side all along the ridge beam  14  on both sides of the ridge, with the shear member  46  of each panel  11  supported on one of the support surfaces  77  or  78  (the other end of each panel  11  is supported by the bond beam  67  as described above). This placement of the panels  11  creates a ridge beam channel  82  all along the ridge. The channel  82  has a channel floor  83  (portions of the ridge beam  14  support surfaces  77  and  78 ) and channel side walls formed by panel end edges  23  into which the shear member anchor bolts  52  and ridge beam anchor bolts  79  extend. 
     The ridge beam  14  used for the shoring is pre-cast so there is no structural connection holding one section of the ridge beam  14  to another section across the truss  16 . There is also nothing connecting the panels  11  on one side of the roof to panels  11  across the ridge on the other side. 
     To establish these necessary connections, the ridge beam channel  83  is filled with concrete to at least the level necessary to contain the anchor bolts  71  and  52 . A channel keystone  87  that supports the load of the panels  11  is thus created. The keystone  87  with the anchor bolts  52  and  79  secured within it connects all of the panels together at their end edges  23 , and a continuous tie (by virtue of the concrete and anchor bolts  52 ) is created running the full length of the ridge. The channel keystone  87  insures that there is a continuous boundary element where the panels  11  face each other running the full length of the roof and that each panel  11  is connected to its opposing neighbor on the other side of the channel keystone  87 . It is this arrangement that allows the roof panels  11  to resist deformation by thrusting against each other and the walls  18  at bond beams  19 . 
     When the keystone  87  is in place, the ridge beam  14 , which served as shoring for the panels  11  during construction, can be removed as a redundant support structure. The ridge beam anchor bolts  79  are provided only if the ridge beam  14  is to be left in place to prevent the ridge beam or sections of it from falling in a seismic event. 
     A superstructure  91  ( FIG. 17 ) is constructed onto and above the channel keystone  87  to house hydronic supply conduits  92  and  94  and hydronic return conduits  96  and  98 , as well as any other systems that might be advantageously located at the roof peak. The superstructure  91  can take several forms and be constructed of wood, tiles, metal or any other material capable of providing the necessary structural and weather-resistant characteristics. 
     In one embodiment of the invention, a hydronic system is incorporated to provide improved thermal performance. This hydronic system enhances the temperature control of the basic system substantially by using the solar gathering aspects of the concrete slabs to cool and heat the building's interior using a miniscule amount of electrical energy to drive a small in-line recirculating pump (not shown). 
     Referring to  FIGS. 6 ,  18  and  19 , in one embodiment of the invention, two layers of hydronic tubing are cast into the panels  11  with their ends extending out of the panels for connection to common supply and return conduits. A particular material suitable for the tubing is polyethylene and, preferably, each layer is a single piece of tubing without any joints other than end connections. 
     One layer of tubing  101  is disposed on the side of the foam slab  26  nearest the panel bed  36  (roof side). Preferably, the tubing is disposed in contact with the panel bed  36  such as in the upper surface  27  of the foam slabs  26  between the foam and the covering mesh frames  31 . Each tube  101  has its supply end  101   a  connected to a common supply conduit  92  and its other end  101   b  connected to the common return conduit  94 . Water or other cooling medium is supplied through common supply conduit  92  to the supply end  101   a . The fluid flows through the panels  11 , making at least two passes (four passes are illustrated) along the panel length (the number of passes depends on the particular configuration of the tubing) before exiting through return end  101   b  of tube  101  to the common return conduit  94 . In this way, fluid can flow continuously through all of the tubes  101  at the same time. 
     A second layer of tubing  102  is disposed on the side of the foam slab  26  nearest the panel floor  37  (ceiling side). Preferably, the tubing is disposed in contact with the panel floor  37  such as in the lower surface  228  of the foam slabs  26  between the foam and the covering mesh frames  32 . Each tube  102  has its supply end  102   a  connected to a common supply conduit  96  and its other end  102   b  connected to the common return conduit  98 . Water or other cooling or heating medium is supplied through common supply conduit  96  to each panel supply conduit  102  at its supply end  102   a . The fluid flows through the panels  11 , making at least two passes along the panel length (the number depends on the particular configuration of the tubing) before exiting through return end  102   b  of tube  102  to the common return conduit  98 . In this way, fluid can flow continuously through all of the tubes  102  at the same time. 
     It will occur to those skilled in the art that having only one layer of tubing (either roof side or ceiling side) is a design choice and within the scope of the invention. Similarly, the rate at which fluid flows, the fluid used and the selection of tubes (ceiling and/or roof) to have operational are all choices made possible by the invention. 
     The hydronic tubes can provide thermal control in multiple ways. The roof side tubes  101  are used to help keep the interior cool and to provide a heat source that can be used in other ways. Cool water is run through the panels to siphon off solar gain. Solar radiation generates an enormous heat load (in many parts of the world during the summer) that would eventually make it into the interior of the building where it is unwanted. By siphoning off this heat, the interior of the building is kept cooler. Additionally, the heat generated on the roof can be taken to some place where its energy can be put to good use. For example, to a storage tank that can be used for hot water or as pre-heated water for use in a hot water system. It can be used as a heat source to heat the building in the winter. It can also be used to drive an absorptive chiller that uses the energy from the heated water to generate chilled water, thus replacing the need for or augmenting conventional air conditioning. 
     The ceiling side tubes  102  are used to “actively” affect the interior temperature of the building. If the combination of heat siphoning and the thermal mass and insulation of the roof system is insufficient to keep the building at the desired temperature, then the ceiling side hydronic tubing  102  is brought into play. Chilled water (with glycol) can be run through the ceiling plane tubes  102  to actively add cooling to the interior of the building on a hot summer day or night. Additionally, in the winter, the hydronic tubes  102  are filled with heated water (either from the roof tubes alone or augmented with a boiler) to heat the building. Note that this type of heating is considered the “Cadillac” of heating systems because it uses radiant energy to heat the bodies in the room without directly heating the air. It is preferred to radiant floor heating or forced-air heating. The ceiling plane is also relatively unobstructed (people typically don't put rugs on it or dining room tables over it) so that the area is maximized and the overall efficiency of the system is improved. 
     Most fires that start in buildings escape through the roof and most fires that enter buildings enter through the roof. Entry starts either by hot embers landing on the roof surface and migrating to the interior or, more violently, by flames reaching up the wall and eroding the underside of the overhang at the eaves and entering the building at the juncture between the wall and the roof. The present invention provides for a much-improved level of fire resistance over conventional roofs. The roof system of the present invention is constructed of concrete, which is the most fire-resistant modern construction material. Further, this highly fire-resistant material is positioned where it is needed most for fire protection—on the surface of the roof and at the eaves. The hydronic embodiment potentially provides an unprecedented level of fire resistance because water running through pipes will provide an unlimited fire resistance to both the ceiling and the roof surface. The fire rating wouldn't just be 20 min., 40 min., 1 hr., or 4 hrs., it would be “infinity.” By connecting the switch for the circulating pump to the fire alarm system, water can be made to flow through the roof panels whenever a fire is present. This trigger would be independent of and override any other controls that sense the building's temperature or outside solar gain. 
     Of course, various changes, modifications and alterations in the teachings of the present invention may be contemplated by those skilled in the art without departing from the intended spirit and scope thereof. As such, it is intended that the present invention only be limited by the terms of the appended claims.