Patent Publication Number: US-RE38950-E

Title: Waterproof decking method and apparatus

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a waterproof deck and to a method of making a waterproof deck and especially to an apparatus and method which prevents the accumulation of water between a concrete floor and the waterproof membrane on the subfloor. 
     In the past, it has been common to make concrete decks for apartment buildings and the like in which the deck is placed between walls on three sides and open on the fourth side. Decks are typically made with joists mounted between the walls and a plywood subfloor attached to the joists. Typically, a waterproof membrane, such as building paper, coated felt roofing material, roofing asphalt or the like, is used to coat a subfloor and then a concrete flooring is poured on top of the waterproof coating to form the floor. A drip edge is commonly used along the open edge of the deck. The deck may have a slight slope so that rain or water falling onto the deck drains off the concrete and over the drip edge. Prior art decks of this type have tended to have the subflooring and joist rot out in a fairly short period of time as a result of the accumulation of moisture from the concrete below the concrete flooring. In a typical deck of this type, flashing has been placed around the deck along the walls adjacent the attached deck and a waterproof sheathing has been placed on the subfloor so that water accumulating from the concrete floor tends to accumulate under the concrete floor and tends to get through or around the waterproof sheathing placed on the subfloor. This happens because the sheathing is sometimes not fully watertight and at other times tends to get damaged, such as with minute holes that allow the seepage of water therethrough. The water that accumulates under the concrete floor has no where to run off and thereby tends to accumulate and build up until any leak or spacing around the flashing allows the seepage to make its way to the wooden subfloor and joists which then very quickly rot out and causes extensive damage. 
     For efficient water shedding at the deck and roof edges of a building, a metal drip edge is usually installed. These have various shapes and may be formed from 26 gauge galvanized steel. They extend back about three inches from the deck edge and are bent downward over the edge and may have an outwardly bend or lip at the edge of the metal to cause the water to drip free of the underlying deck or joist construction. It has also been common in the past to use T-bar edge materials extending over a roof edge especially in flat or built-up roofs where the metal portion of the T-bar extends over the roof sheathing and also has raised edges to act as a metal gravel stop for containing gravel covering the built-up roof. Built-up roofs commonly use sheathing paper or felt as well as corner flashing to protect the surfaces. 
     The present invention is directed towards a system for preventing the damage by the rotting of concete floor decks wooden components commonly used in multi-story buildings and the like and provide an apparatus and method for preventing accumulation of the water and moisture over and beneath the concrete surface. 
     Prior U.S. patents that have been found of interest to the present invention include the O&#39;Riordain, U.S. Pat. No. 4,274,238, for a roof structure providing for efficient drainage of flat roofs and includes a drainage board above a water barrier layer and below a thermal insulation layer so that water falling on a flat roof passes through the protective layer of gravel through the abutting joints of a thermal insulation layer and through the drainage board and to conventional water gulleys and downpipes. In the VanWagoner, U.S. Pat. No. 4,719,713, a thermally efficient protected membrane roofing system is provided which also includes a drainage and insulation board and a vapor barrier. The seams between adjacent roofing panels is covered with a waterproof but vapor permeable tape and the panels are covered with a protective layer. The Paquette, U.S. Pat. No. 4,937,990, shows a ventilation system for roofs which makes the drying of roof insulation easier. The Paquette et al. U.S. Pat. No. 5,144,782, similarly has a double level drainage system for flat roofs so that water which may collect between the upper and lower membranes of flat, horizontal, or slightly sloped roofs upon perforation of the upper membrane. The insulated panels located between the two membranes are provided at both their upper and lower faces with a network of intersecting grooves and a lower drain is sealed to and opens through the lower membrane to drain any water that has seeped thereinto. The Carter, U.S. Pat. No. 3,434,260, has a series of separately formed gutters underlying the joints between adjacent tiles so that water penetrating the joints is drained by the underlying gutter to the next floor tile and onto the aligned next lower channel. The LaRoche et al., U.S. Pat. No. 4,663,894, is a flexible gutter attached beneath expansion joints for draining off water seeping between the expansion joints at the abutment of interconnecting concrete surfaces. The Riley et al., U.S. Pat. No. 4,658,554, is a protected membrane roof system for high traffic roof areas having a waterproof membrane attached to the roof deck and extruded panels of closed cell polystyrene foam mounted on top of the membrane to protect the membrane from thermal cycling, ultraviolet rays, and physical damage and is resistant to water. Concrete panels are laid directly on top of the polystyrene foam. In the Ager, U.S. Pat. No. 2,646,011, a roof gutter is provided for flat roofs which forms a trough section and spillway with specially formed sheet metal. 
     The present invention provides a simplified disposal of accumulated moisture through a concrete floor to prevent the accumulation of moisture between the floor and the waterproof membrane covering the subfloor so that the cost of building the decks does not increase substantially while preventing subfloors, joists, and the like from rotting out. The problem results because concrete does not provide a total barrier to the passage of moisture and water tends to accumulate beneath the concrete surface where the concrete surface is frequently covered with water. Generally, building codes require that concrete floors always have a moisture barrier placed over any wooden surfaces to which the concrete is to be placed upon. This, however, has not been effective in preventing the wood structure which supports a concrete deck from being damaged by the accumulation of moisture which finds its way through or around the waterproof membrane. 
     SUMMARY OF THE INVENTION 
     A method of making a waterproof deck includes the steps of applying a metal drip edge strip to one edge of a deck subfloor and then applying an elastomeric waterproofing material over the subfloor. A strip of T-bar material is selected and attached to the edge of a deck subfloor over some spacing strips of the elastomeric material with one portion of the T-bar strip extending over the drip edge and a second portion forming an upright raised edge and then pouring concrete over the elastomeric waterproofing material covering the subfloor to a level approximately to the top edge of the T-bar strip so that a concrete deck is provided with water runoff over a T-bar and water under the concrete floor drains over the drip edge under the T-bar. The selected T-bar has a second drip edge formed thereon and is spaced with additional elastomeric waterproofing material. A waterproof deck includes a deck subflooring supported on joists adjacent a building, a flashing adjacent a building, and a drip edge attached along the edge of a subflooring where the water runs off the deck. An elastomeric waterproofing material covers the subflooring and a strip of T-bar edging is attached along the edge of the subfloor and has a portion extending over the elastomeric waterproofing material and over the drip edge and another portion extending above the subfloor to form a raised edge therealong. Concrete covers the elastomeric waterproofing material and subfloor to the top edge of the T-bar raised edge so that water on the concrete flooring runs off the deck over the T-bar drip edge and drain from beneath the concrete floor over the drip edge to prevent collection of water over the concrete flooring. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects, features, and advantages of the present invention will be apparent from the written description and the drawings in which: 
         FIG. 1  is a partial perspective view of a deck under construction; 
         FIG. 2  is a partial perspective view of a deck under construction with metal drip installed; 
         FIG. 3  is a partial perspective view of a partially finished deck having the elastomeric waterproofing membrane over the subfloor; 
         FIG. 4  is a partial perspective view of a partially fin deck having a T-bar strip added thereto; 
         FIG. 5  is a partial perspective view of a concrete deck; and 
         FIG. 6  is a sectional view of a finished deck section. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIGS. 1-6  of the drawings, a portion of a concrete deck  10  in  FIG. 5  is formed by first attaching a subfloor  11  in  FIG. 1 , which subfloor may be ¾ plywood or tongue and groove subfloor. The subfloor  11  is mounted to adjacent concrete or wood sidewalls  12  and rear walls  13 . The deck has an open front. A pair of 2×10 wooden joists  14  are shown supporting the front edge of the subflooring but other joists could also be incorporated into the deck. The subflooring  11  has metal flashing  15  attached at the corners over the edge of the subflooring and along the walls  12  and  13  and has outside corner flashing  16  applied to the wall corner. In the case of a post support, the flashing  15  and  16  is wrapped around the post. 
     In  FIG. 2 , a drip edge  17  has been attached along the front edge  20  of the subfloor  11  which edge is the open side of the deck and adjacent the front supporting joint  14 . The drip edge  17  has a metal portion  18  extending a short distance over the subflooring  11  along the subflooring edge  20  and then a vertically extending portion  21  extending in front of the subflooring  11  with an angled lip  22  to form the edge of the drip edge for draining water therefrom. A waterproof membrane which may be an elastomeric waterproof material  23 , such as BITUTHENE by W. R. Grace Co., which is a rubberized asphalt with four mils of high density polyethylene, and provides a flexible waterproof material which is self-sealing at the edges  24 . However, other waterproofing elastomers can also be utilized without departing from the spirit and scope of the invention. 
     The deck under construction in  FIG. 3  has a plurality of spacers  25 , such as 4×4 inch spacers of the elastomer material  23  placed along the front edge  20  of the subflooring  11 . As seen in  FIG. 4 , a measured strip of metal T-bar material has the one leg  27  placed on top of the spacers  25  and on top of the elastomeric material  23  over the front edge thereof and directly over the drip edge  17 . The drip edge  17  can be anchored to the subfloor and to the joist with nails or other fasteners as desired and the T-bar stud is similarly anchored with nails  28  or the like through the drip edge  17 , top portion  18  and through the T-bar strip portion  27 , as shown in FIG.  6 . The T-bar strip has a raised edge  30  having a reinforcing lip  31  along the top thereof and also has a downwardly extending portion  32  having an angled lip  33  thereon which acts as a drip edge. The elastomer  23  has also been extended and turned down over the drip edge to form a front edge  34 . 
     The T-bar strip is attached in  FIG. 4  along the front edge  20  of the subfloor such that a parallel space  35  is formed between the T-bar strip and the drip edge  17  so that the lip  22  of the drip edge  17  and the lip  33  of the T-bar strip  30  are spaced from each other. This allows moisture to drip off without running down the sides of the wall of a building or the front edge of the deck. 
     Once the deck has been completed, as shown in  FIG. 4 , the concrete floor  36  is then poured to the approximate top edge  37  of the raised edge  37  and within the confines of the flashing  15  along the sides and over the waterproof barrier of elastomer material  23  covering the subfloor  11  (FIG.  5 ). Water from rain covers the top of the concrete deck and drains off the front open end of the slightly angled deck and drains over the T-bar strip  30  and off the lip  33 . However, since the concrete is not a complete barrier to the passage of moisture, it tends to accumulate under the concrete. The water accumulates on the waterproof elastomer barrier  23  which is also angled with the deck and the water flows along the elastomer material until it passes under the T-bar anchoring portion  27 , past the spacers  25  and over the drip edge  17 , and off the drip edge lip  22  to be separately drained and thereby prevent accumulation on the surface of the elastomer coating  23 . The subflooring  11  and the joist  14  are protected from moisture seepage through water getting around the flashing  15  from above and through the concrete and seepage through pinholes or other areas of the membrane to cause the joist and subfloor to rot. 
     It should be clear at this time that both a concrete deck and a method of making a concrete deck have been provided. However, it should be clear that the present invention is not intended to be limited to the forms shown which are to be considered illustrative rather than restrictive.