Exterior wall panel drainage system
BACKGROUND OF THE INVENTION 
     Attempts have been made in the past to drain rain water and moisture from exterior wall panel systems but they have not met with success in accomplishing this task. Present industry practice is to apply sealant to the face of the support system, then squeeze it to a thin film when the panel is placed snuggly against the support. This thin sealant bead breaks down easily when any of the components of the system moves thermally or due to settlement. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to overcome the above-mentioned disadvantages. It relates to a drainage system for draining rain water and internal moisture from the rear of exterior wall panels so as to effectively drain such rain water and moisture outwardly to the outside of the wall panels. The system includes a vertical sealant joint behind adjoining exterior wall panels to sealingly space the wall panels from their support, the space including foam back-up tapes, vertical sealant, drain tubes, and gutters so arranged as to effectively drain, outside the walls, through weep holes, rain water as well as moisture that tends to accumulate behind the walls. The present system drains both the vertical and horizontal joints of exterior wall panels. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view showing one of the adjoining panels cut away so as to better illustrate the rear drainage system for draining rain water and moisture in accordance with the present invention; 
     FIG. 2 is a top view thereof showing both adjoining panels; 
     FIGS. 3a and 3b are vertical cross-sectional views of the left panel of FIGS. 1 and 2; 
     FIGS. 4a and 4b comprise a vertical cross-sectional view of a panel module modification including a coping and base trim but not including a gutter or drain tube; and 
     FIGS. 5a and 5b comprise a vertical cross-sectional view showing a drainage system for the head and seal of a window. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring more particularly to FIG. 1 of the drawings, which is a cut away perspective view of the drainage system of the present curtain wall invention, numeral 1 denotes a support mullion having attached to one side thereof, a back-up flash or flashing 2 of metal or plastic, against which there is supported a vertical extending foam back-up tape 3 sealed on one side by a continuous silicone sealant 4 of about 3/8 inch thickness which may be &#34;tooled in&#34; from the outside to serve as a side dam for drainage water and providing the primary seal. This serves as a substantial improvement over formerly used thin film, mashed in place seals. 
     A horizontal drain tube 6 of plastic or other suitable material is provided at each end with an open cell foam baffle 7, an insulating panel 8, such as one of rigid polyisocyanurate, having an outer metal covering 13, an inner metal covering 9 and an anchor clip and fastener 10 covered by a sealant 11 and including an end dam 12 of silicone or other suitable sealing material. 
     It will be understood, by reference to FIG. 2, that a second foam back-up tape 3, sealant 4, baffle 7, drain tube 6 and gutter 14 are provided for the panel to the right. 
     Referring to FIG. 3a, it will be noted that the back-up flashing 2 has a portion 2a which tucks into a continuous extruded aluminum gutter 14, provided in one panel joint per floor in those areas with no windows. Tube 6 rests in an extruded aluminum gutter 14 extending throughout the width of the panel to provide secondary drainage. In FIG. 3b, a spacer 17 is provided between panel 8 and mullion 1. 
     The internal secondary drainage gutter 14 will drain to the exterior face of the wall any potential water entering at joints and/or any condensation occurring within the wall construction. Weep holes which will be concealed will drain the condensation to the outside panel wall 13. 
     It is preferred that the extruded aluminum gutter 14 be sealed to the panel system and by nesting it within the joint system, it is automatically sealed continuously when the panel above, shown in dash lines, is put into place, and the gutter&#39;s edge is continuously sealed throughout when it enters into the factory-applied sealant 4 within the female pocket. 
     In operation, water such as rain water or moisture descending on the outer face of back-up flashing 2, will be diverted by the tucked in portion 2a and the rear wall of panel 8 towards the drain tube 6 and gutter 14. Rain water entering from the outside of wall panel 8 will be arrested by sealant 12 which serves as a rain screen. As shown in FIG. 2, the vertical joint rain screen gasket 22 is intended to prevent entry of rain water between the wall panels; however, if leakage occurs, it will be guided by the back-up flash 2 and its tucked in portion 2a into the horizontal gutters 14. 
     Water leakage from back-up flash 2 entering open cell foam baffles 7 will enter the drain tubes 6 and drip downwardly between adjoining panels and will be sealed in by rain screen gasket 2 (FIGS. 1 and 2). If leakage occurs due to failure of the back sealant at the panel back face or the marriage bead or gasket 22, water will hug back of the panel and drain into the gutter 14, then drain out through the weep holes. Such drain tube 6 is provided in panel-to-panel gutters only. In the lower part or FIG. 3b showing a typical panel side joint, leakage moving down vertically to the sealant will hug back of the panel or be guided by the back-up flashing 2 into the gutter system. 
     FIG. 4a shows an upper portion of the wall panel which is provided with an extruded coping anchor 19 on which is mounted a formed metal coping 20, which may have an inner layer of 20 mil vinyl membrane (not shown) extending to the parapet back-up and roofing materials 21. 
     FIG. 4b shows extruded base trim 15 set into the sealant which extends vertically along the back-up flashing 2. Weep holes 15b, 15a will conduct any leakage away from the building. 
     FIGS. 5a and 5b shows portions above and below the window module. Any potential moisture or condensation will be guided by the back-up flashing 2 tucked at 2a into the gutter 14 and will be drained out through the lowermost weep holes 23, in turn, to the weep holes 24 spaced towards the front of the exterior wall panel. Likewise, any drainage from the bottom of the window 26 will flow through the weep hole 25 and flow outwardly to the front of the building panel. 
     Thus, effective drainage is provided in both the horizontal and vertical panel joints, a unique feature. Moreover, a continuous gutter or flashing is provided around the building perimeters, usually at every window head or floor level for the purpose of draining infiltrated moisture and condensation. Such moisture will weep from the gutter at vertical joint lines or baffled weep holes in window heat extrusions. 
     The curtain wall of the present invention and window framing systems are thus designed to provide for such expansion and contraction of component materials, as will be caused by an ambient temperature range of 150 degrees without causing buckling, stresses on glass, failure of joint seals, undue stress on structural elements, damaging loads on fasteners, reduction of performance, or other detrimental effects. 
     Thus it will be seen that a complete drainage system is provided by the present invention, including tubes, gutters and weep holes to completely rid the interior of the building of any rain water or moisture from condensation and drain it to the outside of the exterior panel system.