Abstract:
The invention discloses an improved seal for providing protection against water, water vapor, and other vapors from entering into and permeating through a concrete slab. The seal includes three primary functional edges extending from a common junction, a first edge positioned substantially horizontally to be moisture proof fastened to a geo-membrane liner over which a slab is to be poured, a second edge extending downwardly to the first edge to be embedded into a foundation, and a third edge extending upwardly from the first edge to be embedded into the slab. The invention applies to both monolithic and non-monolithic pours.

Description:
CLAIM FOR BENEFIT OF EARLIER FILING DATE 
     This application claims the benefit of U.S. Provisional Application No. 60/470,623 filed on 16 May 2003 and entitled “Water and Water Vapor Structural Barrier”. This utility application has the same inventors, subject matter and title as the said Provisional Application. 
    
    
     BACKGROUND 
     The background of the invention will be discussed in two parts: 
     1. Field of the Invention 
     This invention relates to water and water vapor proofing and more particularly to the fastening and sealing of a geo-synthetic membrane under a concrete slab and/or to footings of an on grade or below grade foundation under any structure, to seal off water and water vapor at the joints between the foundation and slab and the areas directly under the slab foundation. 
     2. Description of the Related Art 
     Water and water vapor proofing of on grade or below grade concrete slab floor is an essential consideration during construction of residential, commercial and industrial structures. Evapo-transportation of molecular water from the subsoil to a water vapor state and transportation of the water vapor by vapor drive through the capillaries of the concrete foundation is a naturally occurring event. The water vapor molecules pick up the concrete salts through osmosis as they pass through the capillaries of the concrete and then pass through the carbonated cement paste of the concrete foundation to escape into the atmosphere of the structure. When water vapor molecules encounter a non-permeable or sufficiently dense structure the water vapor molecules convert back to water molecules. Since the water vapor molecules carried the salts of the concrete, the water molecules have an increase in pH to as high as 14. This combination of elevated water vapor transmission through the concrete foundation and the resulting increase in the pH of the water molecules presents the leading cause of adhesive, flooring and coating failures for above grade and below grade concrete slabs. These failures contribute floor covering problems such as adhesion loss, warping, peeling, buckling, staining, offensive odors and mold growth. 
     Traditionally, newly constructed structures require a moisture/vapor barrier such as polyethylene sheeting that is placed directly under an on grade or below grade concrete floor slabs. However, these polyethylene liners alone are inadequate in restriction of water and water vapor through concrete floor slabs for at least the following reasons: 
     1) Water/vapor will pass through the lap seams of the sheeting. 
     2) Water/vapor will pass through plumbing/electrical openings of on grade foundations. 
     3) Water/vapor will pass through the perimeter and interior of the foundation and throughout the plumbing and electrical trenches. 
     4) The durability of polyethylene sheeting under on grade foundations as a water/vapor barrier is questionable in that it cannot withstand the normal construction activities surrounding on grade or below grade foundation installation, i.e., it will puncture under normal foot traffic. 
     Another consideration is that water vapor molecules can pass through standard 6 to 10 mil polyethylene sheeting, which is the minimum requirement specified by the Uniform Building Code. 
     The prior art includes various approaches for providing a barrier to moisture permeation from the subsoil to above-slab coverings. One such approach is disclosed in U.S. Pat. No. 6,189,279, entitled Floating Floor Underlay, issued to Fiehtl on Feb. 20, 2001, that discloses a composite underlay product for a floating floor. This product is made from a vinyl film (like polyethylene) that creates a moisture impermeable underlay when laid over a wood or concrete sub-floor. The seams between butting sheets of the underlay are sealed with moisture impermeable tape. Another prior art patent is U.S. Pat. No. 5,376,429, entitled Laminated Water Stop Bentonite and Bentones, issued to Mcgroarty on Dec. 27, 1994, that discloses a water/water vapor barrier between the concrete footing and slab using a strip of Bentonite tape for a seal, the seal installed without changes to the concrete installation. 
     Thus, in view of the known prior art, an apparatus and method is needed that will provide an improved water/water vapor barrier that prevents permeation of water/water vapor through an on grade or below grade floor concrete floor slab. Applicants&#39; invention provides such a barrier. The invention provides means for sealing of polyethylene liners at termination points as well as a water/water vapor seal barrier at the cold joints between the footing and slab that restricts intrusion of gases, vapors, liquids and insects without requiring revised construction practices, other than the wet setting of the water/water vapor seal into the concrete footing or direct placement within the concrete form work. 
     SUMMARY 
     The invention provides an apparatus and method for improved protection against water, water vapor and other liquids and gases from entering into and permeating through on grade or below grade concrete floor slabs. There is provided a water/water vapor seal for welding to a conventional membrane liner resulting in a continuous seal at the termination points. The seal has three functionally distinct planes or edges connected at a common point, a first edge embedded into the lower foundation concrete acting as an anchor and to minimize any water, vapor, and/or gas migrating from underneath the membrane liner, a second edge positioned between the foundation concrete and upper or adjacent concrete slab that is used as a point for fastening, such as by welding, to the membrane liner, and a third edge embedded in the upper or adjoining concrete to minimize any water, vapor and/or gas penetrating the upper/lower concrete cold joint due to hydrostatic or gas pressure. 
    
    
     
       DRAWINGS 
         FIG. 1  is a perspective view of the water/vapor seal in accordance with the invention; 
         FIG. 2  illustrates a typical installation of the water/vapor seal of  FIG. 1  within a footing prior to a concrete on grade slab pour in accordance with the invention; 
         FIG. 3  illustrates the water/vapor seal installation of  FIG. 3  after the concrete slab pour, typically used for basement construction; 
         FIG. 4   FIG. 1  is a perspective view of the water/vapor seal of  FIG. 1  illustrating welding thereto of a membrane liner in accordance with the invention; 
         FIG. 5  illustrates positioning of the welded membrane liner to the proper edge of the water/vapor seal in accordance with the invention in preparation for a concrete slab pour; and 
         FIG. 6  illustrates in cross section a monolithic concrete pour wherein a foundation footing and a floor slab are poured at the same time. 
     
    
    
     DESCRIPTION 
     In accordance with the invention, apparatus and method is provided to improve protection against water, water vapor, and other vapors from entering into and permeating through a concrete slab to accumulate on top of the slab. A unique water/water vapor seal is provided for use at the foundation “cold joint” in conjunction with a conventional moisture barrier, or membrane liner. By fastening, such as by welding, of the membrane to the water/water vapor seal at the “cold joint”, an improved termination point is provided that results in a continuous seal along the membrane. The fastening of the membrane liner to the water/water vapor seal creates a monolithic barrier between the sub-grade and slab for on grade or below grade foundations, minimizing water, water vapor, other liquids and gases that permeate through the concrete slabs and trans-evaporate back to a liquid. 
     Referring now to the drawings, the invention will be described in detail wherein the elements of the invention are identified by reference numerals, like reference numerals referring to like elements in the several views. 
       FIG. 1  is a perspective view of the water/vapor seal, generally designated  10 , in accordance with the invention. As illustrated, the water/water vapor seal  10  has three primary functionally distinct planes or edges, that is, edges  11 ,  12 , and  13 , joining at a common point α. From the common point α, edge  11  and edge  12  are at approximately right angles with edge  13  at an obtuse angle of approximately 110 degrees from edge  12 . As disclosed in the following description, in accordance with the invention, edge  12  is installed approximately horizontally from the common point with edge  11  installed approximately vertically downwardly therefrom. Edge  13  extends upwardly from the common point at the obtuse angle from edge  12  of approximate 110 degrees. Thus, edges  11  and  13  extend from the common point in opposite directions, edge  11  approximately vertically downward and edge  13  approximately 20 degrees from the vertical upwardly. A secondary edge  14  is shown depending downwardly from the end of edge  11  opposite from the common point, the function of which will be described below. 
     Typical dimensions for the edges are: one inch for edge  11 , 2 inches for edge  12 , and 1½ inch for edge  13 . If edge  14  is used it is typically of one inch. 
     The seal  10  is typically formed in six-foot lengths of any suitable material that is compatible with fastening to the membrane liner  15  as will hereinafter be described. However, materials, dimensions, angles and the number of edges indicated or described herein are illustrative of a typical seal, but are subject to variation as the installation may require. Thus, although not shown, other embodiments with different configurations can be used depending on the water/water vapor barrier requirements of a particular job site. 
       FIG. 2  illustrates a typical installation of the water/vapor seal of  FIG. 1  within a footing prior to a concrete slab pour. Primary edge  11  is embedded at pour into the lower layer foundational concrete  20  to form an anchor for the seal  10 , edge  11  positioned in concrete  20  prior to or after the pour of concrete  20  such that edge  12  will extend substantially horizontally along the surface of concrete  20  to provide a platform to which the membrane  15  (see  FIG. 4 ) is fastened and over which the surface concrete (not shown) is poured. Thus, edge  12  is positioned between the lower foundational concrete  20  and the upper surface concrete slab. Edge  12  additionally provides a guide for the installer to verify that the edge  11  is properly embedded in concrete  20 . 
     Positioned in this manner edge  13  extends upwardly for embedding in a structure such as a concrete wall  22  as shown in  FIG. 3 , or within the concrete slab floor  26  as shown in  FIG. 5 . Secondary edge  14  may be included as a means for minimizing inadvertent “pull out” of edge  11  from the concrete  20 . Also shown in  FIG. 2  is concrete formwork  23  and anchor bolts  24 . 
       FIG. 3  illustrates the water/vapor seal installation after the pour of a concrete wall  22  on top of a spread footing. As shown, edge  13  extends upwardly into concrete wall  22  at an appropriate obtuse angle from edge  12  to effectively serve as a “deflector” to deflect the flow of water, water vapor and/or gas migrating from foundation concrete  20  back toward the “cold joint”  27  between concrete  20  and wall concrete  22 . The cold joint  27  presents the path of least resistance to the flow of water, water vapor and/or gas, thus this flow will be along the cold joint  27  and outward of the wall  22 , or inward under the membrane liner  15  (see  FIG. 5 ). The result is to minimize flow around edge  13  and thus to accumulate on top of the membrane  15  and thus to permeate through the surface slab as more clearly illustrated in  FIG. 5 . 
       FIGS. 2 &amp; 3 , in sequence, illustrate a non-monolithic pour in accordance with the invention where concrete footing  20  is first poured with the concrete wall  22  or concrete slab  26  poured second. 
       FIG. 4  is a perspective view illustrating fastening of membrane liner  15  to the water/vapor seal  10 . Typical six-foot lengths of seal  10  are butted together lengthwise end-to-end and typically extrusion welded together to form the desired length in accordance with the desired length of the footing. The termination end  15   a  of liner  15  is positioned over edge  12  of seal  10  and typically extrusion welded along the termination end to edge  12 . 
     The liner  15  is thus attached to edge  12  of the seal  10  in a manner to eliminate water, vapor or gas from penetration between the membrane  15  and the seal  10 . Edge  13  minimizes the migration of water, vapor or gas from flowing around the seal  10 . Where there is a propensity for such migration around seal  10 , water vapor or gas will tend to escape at the cold joint  27  since cold joint  27  presents less resistance that the denser concrete  22 . Further, edge  13  will act to deflect such migration to additionally force it back to the cold joint instead of trying to flow up and around concrete encapsulated edge  13 . 
     The integrity of the connection of the termination end  15   a  of membrane liner  15  to seal  10  is critical in ensuring that the membrane liner  15  is an adequate water, water vapor and gas barrier. Adequate connection of the membrane liner  15  to the seal  10 , as well as any necessary seaming of adjacent panels of liner  15  is typically accomplished by extrusion welding wherein for a plastic material such as HDPE, a molecular bond is created. Membrane liner seams between two material panels are first tack welded in place with hot air welding equipment, with seam areas then prepared for extrusion welding by sanding the surface oxidation and other contaminants in the seam areas. Extrusion welding equipment is then used to extrude a bead of molten material along the seam to weld the two pieces together. 
     Hot air welding is a simple procedure using a hand held hot air welding tool and a silicon rubber roller. The welder is equipped with a float air nozzle that distributes the hot air typically in a 1½″ wide pattern. The nozzle is inserted between the overlap of the material and moved along the seam between the two materials to melt the materials together. A hand held roller is moved along the seam, the pressure and heat combination creating a molecular bond between the two materials. 
     In addition to extrusion welding, other appropriate means of fastening the liner membrane  15  to the water/vapor seal  10  can be used. For instance, heat welding, the use of glue or adhesive tape, or other appropriate procedures that would minimize water, vapor, or gas penetrating through the fastening mechanisms can be used. 
     It is important that the welded joint between the seal stop  10  and the membrane liner  15  does not experience undue stress such that the weld separates allowing water, vapor or gases to migrate between the seal  10  and the liner  15 , and thus under any overlying slab. This problem is minimized where the seal  10  edge and the membrane liner is in the same horizontal plane. Where the seal  10  and the membrane liner  15  are in different planes, the weld is subjected to increased stress. Additionally, membrane liners are subject to temperature changes, that is, they will contract or shrink with a decrease in temperature and expand or stretch with an increase in temperature. A typical membrane liner will contract or expand approximately 2 inches with a temperature change of 30 degrees. Thus, the membrane liner  15  will typically be installed and fastened to the seal stop  10  during the day when ambient temperature is typically at its highest. The edges of the seal are designed so that at installation, the termination weld is at the same elevation as the liner so that when the liner is contracting during low temperatures the liners will not lift up and act like a trampoline. If the weld of an edge is installed higher than the membrane liner, lower temperature will tighten the liner and lift the weld or edge. Further, walking on top of the liner can stress the termination points of the liner such that it may stretch beyond acceptable limits, or even to tear, thus decreasing performance of the liner. 
       FIG. 5  is an end view illustrating a non-monolithic pour of a concrete slab  26  overlaying the membrane liner  15 . Membrane liner  15  is welded, as indicated by welding bead  25 , at termination end  15   a  to the seal  10  with edge  12  appropriately overlying footing  20 . Edge  11  is embedded in concrete footing  20  and edge  13  is extending upwardly for encapsulation by pouring of concrete  26 . The sequence of the installation is typically as follows:
         1. The seal  10  is “wet set” into the perimeter of the internal concrete footings  20  during the footing installation.       
     2. After the utilities and sub-grade elevations are completed the membrane liner  15  is installed. The membrane liner  15  is installed in panels over pipe and utility penetrations and extrusion welded as previously described onto the seal  10 . A boot liner flashing system is installed over all pipe and utility penetrations and extrusion welded into the liner  15 . A bead of silicone caulking is installed as a bond between the pipe penetration and the liner boot. A stainless steal clamp is then fastened around the liner boot and pipe or utility penetration.
         3. The termination  15   a  of the liner  15  is extrusion welded to the vapor seal  10 .   4. Appropriate sand, typically one inch, is placed on top of the liner  15  and reinforcement steel is placed on top of the sand layer.   5. The overlying concrete slab  26  is poured and finished.       

       FIG. 6  is a cross sectional view illustrating a monolithic continuous concrete pour wherein the concrete slab  26 ′, overlying membrane liner  15  is poured at the same time as the concrete foundation  20 ′, resulting in elimination of a cold joint. As indicated in  FIG. 6 , seal  10  is positioned such that at completion of the monolithic pour, edge  11  is embedded in the concrete foundation  20 ′ and edge  13  is extended at an angle upwardly and encapsulated by concrete  26 ′. 
     As previously disclosed, membrane liner  15  is welded at termination end  15   a  to the edge  12  of seal  10 , edge  12  extending as appropriate past the vertical edge of the foundation  20 ′ and into the area under slab  26 ′ to join with membrane liner  15 . The sequence of the monolithic installation is typically as follows:
         1. After all concrete formwork, below grade utilities and sub-grade elevations are completed, membrane liner  15  is installed in panels as required and the panels welded together. A boot liner is installed at all penetration points of utility pipes into liner  15 . A bead of silicone caulking is installed as a bond between each liner penetration and a stainless steel clamp fastened around the boot liner and pipe or utility penetration.   2. The termination  15   a  of the membrane liner  15  is extrusion welded to the seal  10 , the seal  10  allowed to free stand over the concrete  20 ′ pour.   3. Sand, typically one inch, is placed on top of the membrane liner  15  and reinforcement steel is placed on top of the sand layer and into the foundation  20 ′ pour area.   4. The monolithic continuous concrete pour starts within the foundation  20 ′ and continues to provide the slab  26 ′, thereby eliminating a cold joint between foundation  20 ′ and slab  26 ′.       

     Although the invention has been shown and described in conjunction with sealing at termination joints between a building foundation and the concrete slab, the concept of the invention would work equally well for water, vapor or gas barriers for walls made from concrete or blocks. 
     The apparatus and method of the present invention provides at least the following advantages over related prior art techniques.
         1. Used as water/vapor stop between the cold joint of the footing and slab.   2. Increases effectiveness of the required vapor barrier liner.   3. Ensures maximum water/vapor protection at the liner termination.   4. Reduces installation time of the liner seam at the liner termination.   5. Does not alter concrete contractor construction procedures in the field.   6. Reduces potential for mold growth at the liner termination by reducing excessive moisture entering from perimeter of the structure form drainage, irrigation, etc.   7. Eliminates less effective vapor barriers normally positioned beneath the perimeter footing of the structure.   8. Compatible with the more effective current water/vapor barrier liners.   9. Eliminates the liner “trampoline” effect due to temperature changes   10. Minimizes peeling stress of the weld between the seal and the liner.   11. Eliminates creasing of the liner or sharp bending of the liner.   12. Insect/bug control.   13. Provides easier building inspector verification of quality control/assurance.       

     The invention has been described with respect to specific details. However, it is understood that variations will be apparent to those skilled in the art, thus, it is not intended that such details limit the scope and coverage of the invention.