Abstract:
A skylight assembly includes a curb which supports the skylight above the roof surface. The curb is formed from four mechanically connected structural insulated panels. The panels include an outer fastener-receiving member such as OSB with an intermediate polystyrene foam layer and an innermost melamine layer. The curb is assembled on site and fastened to the roof structure with brackets. The melamine surface provides a finished interior surface and the curb itself provides thermal insulation.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Skylights can be applied to a roof deck using several installation methods. Certain skylights are supported on a curb which raises the skylight above the surface of the roof. 
         [0002]    Foam insulated curbs have been utilized, such as those disclosed, for example, in Kiekhaefer U.S. Pat. No. 3,417,522; Jentoft et al. U.S. Pat. No. 4,073,097; and Moench et al. U.S. Pat. No. 4,233,493, as well as several others. Generally, these foam insulated curb structures are unitary structures formed in a mold. They may have limited structural integrity and, further, require a separate mold for each different size skylight. Further, since they are unitary in structure, they use a large amount of space during shipping and are difficult to transport and use at the construction site. 
         [0003]    Other structures have been used to form curbing, such as simply dimensional lumber, such as 2×6&#39;s, and the like. These are difficult to assemble on site and, further, lend themselves to irregularities in size and variations in plumb. Further, the wood itself provides less than adequate thermal insulation, making the curb only minimally efficient portion of the skylight. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention is premised on the realization that a skylight curb can be formed from structural insulated panels (SIP). More particularly, the structural insulated panels take the form of elongated plank components with an outer fastener engaging portion and an inner finish portion and an intermediate foam core. The edge structures of each of these planks are designed to provide for easy assembly. An edge of a first SIP plank includes a fastener-receiving insert at the end of the foam core, while the adjacent edge of a second SIP plank includes an elongated fastener-receiving portion, or wood portion, which overlaps the first SIP plank, allowing the two to be screwed together forming a precise 90° angle. Four SIP planks are fastened together to form a curb. 
         [0005]    The formed rectangular curb structure can then be fastened to a roof substructure using L-brackets, or other similar brackets. A water tight seal between the curb and roof membrane is formed using flexible flashing. Finally, the skylight is simply placed on top of the curb structure laid on a bead of waterproofing sealant and fastened into place. 
         [0006]    The objects and advantages of the present invention will be further appreciated in light of the following detailed descriptions and drawings in which: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0007]      FIG. 1  is a perspective view of a skylight curb according to the present invention; 
           [0008]      FIG. 2  is a view of the curb shown in  FIG. 1  prior to assembly; 
           [0009]      FIG. 3  is an exploded view of a skylight incorporating the curb of the present invention; 
           [0010]      FIG. 4  is a perspective view of a skylight that incorporates the curb of the present invention; and 
           [0011]      FIG. 5  is a cross sectional view taken at lines  5 - 5  of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    As shown in  FIG. 4 , a skylight assembly  10  located on roof surface  12  includes a rectangular curb  14  surrounded by flashing  16  with a skylight  18  resting above the flashing and the curb. 
         [0013]    The curb  14  is formed from structural insulated panels or SIPs  20 ,  22 ,  24  and  26 . The SIPs each include an outer portion or layer  28  which is designed to receive and hold a fastener, a central foam portion or layer  30  and an inner finished portion or layer  32 . The length of the SIPs is determined by the size of the skylight while the height can be about 9 inches or more. 
         [0014]    The outer portion  28  can be formed from any material that will receive and hold a fastener. Typically, it will be a wood based material such as plywood, particle board or OSB or metal. In particular, OSB having a thickness of from about ¼ inch to about ¾ inch can be used, and, in particular, OSB having a thickness of about ½ inch to 7/16 inch provides adequate structural integrity. To provide fire retardance a layer of dry wall (not shown) can cover the OSB. 
         [0015]    The foam core is designed to provide insulation and is preferably a rigid foam such as polystyrene foam. It can have any thickness designed to achieve the requisite insulation. Insulation having a thickness of 1 to 5 inches can be used, with polystyrene insulation of 3 to 4 inches generally being considered as adequate, and, in particular, 3⅝ inch expanded polystyrene foam is suitable for use in the present invention. 
         [0016]    The inner portion  32  provides a finished interior surface. It is not designed to be penetrated by any fastener and it is preferable to utilize a material that provides some structural strength to the SIP. In particular, a solid, non-foam plastic or polymeric material is suitable. In particular, melamine coated masonite material having a smooth innermost surface can be used in the present invention. Other materials which are suitable for interior portion  32  include, for example, wood having a finished surface, such as stained or painted wood, as well as other polymeric materials. Any material that does not require additional finishing facilitates installation and reduces expenses. 
         [0017]    The SIP itself is formed by simply bonding the three layers together. This is generally done in a factory so that the SIP is structurally sound and dimensionally precise. 
         [0018]    As shown, SIPs  20  and  22  are attached to SIPs  24  and  26  at corners  34 . The end structures of the SIPs are designed to facilitate formation of these corners  34 . SIPs  20  and  22  include an end portion  36  of the outer portion  28 , which extends beyond the ends  38  and  40  of the foam and finished portion, respectively. Likewise, SIPs  24  and  26  include ends  42 , 46  which incorporate a wood insert  44  at the distal ends of the foam portion  30  wherein the wood insert is coextensive with the ends  48  and  50  of the fastener-receiving portion  28  and the inner finished portion  32 . 
         [0019]    The corners  34  are assembled by simply fixing an end portion  36  of SIP  20  or  22  adjacent an end  50  of SIP  26  and inserting screws  52  through the extended portion  36  into the wood insert  44 . As the wood insert is tightly bound to the SIP, this holds the entire structure together forming a very precise 90° angle. The assembled curb  14 , as shown in  FIG. 1  and  FIG. 3 , is then placed on a roof surface surrounding an opening  54  in the roof surface  12 . Membrane roof material  56  is then applied over the roof surface  12  and the curb is fastened to the roof surface with L-brackets  58  fastened to the side wall  28  of curb  14  with screws  60  extending through the brackets to the fastener-receiving outer surface  28  of the SIPs  20 ,  22 ,  24  and  26 . The L-brackets  58  are then fastened to the roof surface with screws  60  extending through the L-bracket into the roof surface  12 . 
         [0020]    Flashing  16  is then applied over the curb surface. The flashing can be either a continuous strip of flexible flashing, generally with a preapplied adhesive, or can be a preformed unitary structure configured to fit directly over the curb  14 . The flashing  16  extends from the top surface  62  of curb  14  over the side  28  covering the L-brackets with a bottom edge  64  adhered to the membrane  56 . 
         [0021]    Preferably, the flashing is simply adhered to the curb and to the roofing structure with a preapplied adhesive. The skylight  18  is then applied to the upper edge  62  of the curb utilizing a urethane sealant  66 . As shown, the skylight incorporates an integral condensate grill  68  around the inner peripheral edge of the curb adhered to the skylight with an adhesive bonding tape  70 . The outer rim  72  of the skylight is then fastened to the side walls  28  of the curb, again with screws  74 . 
         [0022]    The skylight structure  10  of the present invention provides several advantages. The insulating factor of the SIP is extremely high due to the insulating foam core. The SIP also provides significant rigidity. Further, because the curb assembly can be brought to the roof in sections and assembled at the roof, construction costs are reduced. Due to the structure of the curb assembly, assembling the curb structure on the roof is relatively simple, requiring only tools that would be with the builder at the time. The screwed butt-joined panel edges are designed to provide precise 90° angles. Further, the maintenance free interior with the white melamine coated masonite curb liner  32  provides a finished inner surface that requires no additional trim. 
         [0023]    The risk of cutting the membrane is reduced because no metal flashing is employed, yet the curb and skylight assembly are firmly fixed to the roof using simple L-brackets. Finally, the overall cost of production is significantly reduced. Because the SIPs can be formed without a separate mold, virtually any size skylight can be utilized simply by changing the length of the SIPs. 
         [0024]    This has been a description of the present invention along with the preferred method of practicing the present invention wherein the invention itself should only be defined by the appended claims.