You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/166,412, filed on Dec. 8, 2009, and U.S. Provisional Application No. 61/294,648, filed on Jan. 13, 2010, the entire disclosures of which are incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    1. Field of the Invention 
         [0003]    The present application relates to improved seals for water closets. 
         [0004]    2. Description of Related Art 
         [0005]    In plumbing, a closet flange is a pipe fitting (specifically, a type of flange) that both mounts a toilet to the floor and connects the toilet drain to a drain pipe. The name comes from the term “water closet”, the traditional name for a toilet. A typical closet flange is composed of an ABS, PVC, or metal hub with a round steel mounting flange attached to the top. Other styles are made from copper, brass, stainless steel, or a plastic material. 
         [0006]    In a typical installation, the closet flange is mounted on top of the floor with the hub fused around the drain pipe. A wax ring is used to seal the gap between the flange and the bottom of the toilet. The toilet is bolted to the flange, not to the floor. The existing art can allow water to leak from the wax ring at the discharge point of the toilet. In order to catch this water, it has been proposed in the prior art to provide an impermeable layer that rests above the finished flooring. The impermeable layer is sealed to the mounting flange of the closet flange. 
         [0007]    However, such an impermeable layer is not sealed to the floor membrane. Water from a leaking or overflowing toilet, tub, or sink therefore can flow around the opening created for the plumbing and under the impermeable layer. This is a particular problem in a tiled floor, having recessed areas caused by grout lines. Grout lines under the impermeable layer can provide a pathway for water to travel to the opening in the floor for the toilet drain pipe, and hence to the floor below. 
       SUMMARY OF THE INVENTION 
       [0008]    In light of the present need for improved watertight closet flanges, a brief summary of various exemplary embodiments is presented. Some simplifications and omissions may be made in the following summary, which is intended to highlight and introduce some aspects of the various exemplary embodiments, but not to limit the scope of the invention. Detailed descriptions of a preferred exemplary embodiment adequate to allow those of ordinary skill in the art to make and use the inventive concepts will follow in later sections. 
         [0009]    Many tile floors have a membrane under the tile that holds water in the event that grout lines crack or leak. Leakage of water through the opening in the floor for the toilet drain pipe and closet flange may be prevented by integrating the membrane under a tile floor, or other impermeable layer of flooring, into or with the plumbing system. As described herein, this is done by sealing the flooring membrane at the penetration in the floor caused by a closet flange. Connections between a closet flange and a drainpipe as described herein may be done with a PVC, ABS, or cast iron pipe. 
         [0010]    Various exemplary embodiments relate to a method of installing a closet flange by telescopically fitting an inner or outer surface of a drainpipe to a surface of a first cylindrical portion of a hub of a closet flange. The closet flange has a base flange extending from the hub. The base flange is secured against the upper surface of a subfloor. The next steps include applying a first layer of sealant to an upper surface of the base flange; securing a flooring membrane to the upper surface of the base flange by bonding the flooring membrane to the first layer of sealant; applying a second layer of sealant to an upper surface of the flooring membrane; and clamping the flooring membrane between the base flange and a clamping ring. 
         [0011]    In certain embodiments of the closet flange disclosed herein, the base flange extending from the hub extends from said first cylindrical portion of said hub. In other embodiments, the base flange extending from the hub extends from a second cylindrical portion of said hub. The first and second cylindrical portions of the hub may be, but are not required to be, coaxial. In certain embodiments, the hub comprises a first cylindrical portion which telescopically connects to an inner or outer surface of a drainpipe; and a second cylindrical portion of the hub, where the base flange extends from the second cylindrical portion of the hub. In such embodiments, the second cylindrical portion is fluidly connected with the first cylindrical portion. 
         [0012]    In various embodiments of the method disclosed herein, the step of clamping comprises positioning a clamping ring on the second layer of sealant; and securing the clamping ring to the subfloor. More particularly, the step of securing the clamping ring to the subfloor may comprise securing the clamping ring to the subfloor with a threaded fastener, such as a screw or a bolt, where the threaded fastener passes through the base flange between the clamping ring and the subfloor. 
         [0013]    Alternative methods of securing the clamping ring to the subfloor include using a closet flange having a hub and a base flange extending from the hub. The hub comprises a first cylindrical portion below said base flange and a second cylindrical portion above said base flange, where the second cylindrical portion has an external surface with a first threaded joint. The clamping ring has an internal surface with a second threaded joint, where the second threaded joint is able to screw onto the first threaded joint. The step of clamping the flooring membrane between the base flange and the clamping ring comprises screwing the second threaded joint onto said first threaded joint until the clamping ring contacts the second layer of sealant. 
         [0014]    In certain embodiments of the method disclosed herein, the step of securing the base flange of the closet flange against the upper surface of a subfloor includes applying a third layer of sealant to the subfloor; fitting a sealant dam to an inner peripheral edge of a lower surface of said base flange; and securing the base flange to the subfloor through said third layer of sealant. 
         [0015]    Various exemplary embodiments relate to a method of fitting a closet flange to existing construction having a finished floor, where the closet flange has a hub with a base flange extending from the hub. This is done by fitting a sealant dam to an inner peripheral edge of a lower surface of the base flange; telescopically fitting an inner or outer surface of a drainpipe passing through a hole in the finished floor to a surface of a cylindrical portion of the cylindrical hub; applying a layer of sealant to an upper surface of a finished floor; and securing the base flange to the finished floor or flooring membrane through the layer of sealant. The sealant dam prevents sealant from entering the hole in the finished floor. 
         [0016]    Various embodiments disclosed herein relate to a two-part closet flange for connection to a drain pipe for a toilet. The closet flange comprises a cylindrical hub, the cylindrical hub being adapted to telescopically connect to the drain pipe; an annular flange radially extending from the cylindrical hub; a clamping ring; and a means to clamp a flooring membrane between the clamping ring and the annular flange. Other embodiments relate to a two-part closet flange comprising a hub having a first cylindrical portion, where the first cylindrical portion is adapted to telescopically connect to the drain pipe; and a clamp assembly comprising: 
         [0017]    a) an annular flange radially extending from said hub; and 
         [0018]    b) a clamping ring; 
         [0019]    wherein the clamping ring and the annular flange are adapted to clamp a flooring membrane between the clamping ring and the annular flange. 
         [0020]    Further embodiments relate to a two-part closet flange seal for connection to a drain pipe for a toilet, comprising a cylindrical hub, the cylindrical hub being adapted to telescopically connect to the drain pipe; an annular flange radially extending from the cylindrical hub; a clamping ring; and a means to clamp a flooring membrane between the clamping ring and the annular flange; wherein the means to clamp comprises at least one threaded fastener securing the clamping ring and the annular flange to a subfloor. 
         [0021]    Additional embodiments relate to a two-part closet flange for connection to a drain pipe for a toilet, comprising a cylindrical hub, the cylindrical hub being adapted to telescopically connect to the drain pipe; an annular flange radially extending from the cylindrical hub; a clamping ring; and a means to clamp a flooring membrane between the clamping ring and the annular flange; wherein the means to clamp comprises a first threaded surface on an interior surface of the clamping ring; an annular flange radially extending from a lower edge of the clamping ring; and a second threaded surface on an exterior surface of the cylindrical hub, the second threaded surface extending above the annular flange radially extending from the cylindrical hub. The first threaded surface is adapted to screw onto the second threaded surface so as to clamp a flooring membrane between the annular flange extending from the clamping ring and the annular flange extending from the cylindrical hub. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    In order to better understand various exemplary embodiments, reference is made to the accompanying drawings, wherein: 
           [0023]      FIG. 1  shows an exploded view of a first embodiment of a two-part closet flange seal and its use in installation of a toilet; 
           [0024]      FIG. 2  shows an exploded view of a second embodiment of a two-part closet flange seal and its use in installation of a toilet; 
           [0025]      FIGS. 3 and 3A  show an embodiment of a base portion of a closet flange for use in an embodiment of  FIG. 2 ; 
           [0026]      FIGS. 4 and 4A  show an embodiment of a clamping ring for use in an embodiment of  FIG. 2 ; 
           [0027]      FIGS. 5 and 6  show two views of an embodiment of a mounting ring assembly; 
           [0028]      FIG. 7  shows a view of an alternate embodiment of a mounting ring assembly; 
           [0029]      FIG. 8  shows a clamping ring for use with the alternate embodiment of a mounting ring assembly seen in  FIG. 7 ; 
           [0030]      FIG. 9  shows installation of the alternate embodiment of a mounting ring assembly seen in  FIG. 7  in the base of a toilet; 
           [0031]      FIG. 10  shows connection of a toilet to a drainpipe using a mounting ring assembly seen in  FIG. 7 ; 
           [0032]      FIGS. 11 ,  11 A,  11 B, and  11 C show an alternate embodiment of a base flange and an embodiment of a clamping ring for use in an embodiment of  FIG. 2 ; 
           [0033]      FIG. 12  shows a view of an embodiment of a two-part closet flange seal and its use in installation of a toilet in new construction; 
           [0034]      FIG. 13  shows a view of an embodiment of a closet flange seal and its use in installation of a toilet in existing construction using a sealant dam; 
           [0035]      FIG. 14  shows a view of an embodiment of a closet flange seal having an elastomeric seal for connection to pipes; 
           [0036]      FIG. 15  shows an alternate embodiment of a two-part closet flange seal; and 
           [0037]      FIG. 16  shows an exploded view of the embodiment of  FIG. 15   
       
    
    
     DETAILED DESCRIPTION 
       [0038]    Referring now to the drawings, in which like numerals refer to like components or steps, there are disclosed broad aspects of various exemplary embodiments. 
         [0039]    As seen in  FIG. 1 , an improved seal between a floor and a closet flange may be accomplished with a two-part closet flange  100 , comprising a base portion  102  and a clamping ring  104 . An impermeable floor covering  2 , such as an impermeable sheet or template, is placed directly over the subfloor, decking, or floor base  4 , where the subfloor, decking, or floor base  4  may be made of wood, metal, or concrete. In new construction, the impermeable floor covering  2  is adhered to the base portion  102  of the closet flange  100 . The base portion  102  of closet flange  100  has a hub  106  and an annular base flange  108  extending from the hub. The hub  106  is placed through a hole  6  in the subfloor  4 , allowing a toilet drain pipe  8  to extend through hole  6  in subfloor  4 . The inner surface of a lower cylindrical portion  106   a  of hub  106  is adhesively bonded or fused to the outer surface of the drain pipe  8 . A circular layer of sealant  10  is applied to the lower surface of the annular base flange  108  of the closet flange  100 . Preferably, a sealant dam  12  is positioned against the inner edge of the annular base flange  108  of the closet flange  100 . The circular layer of sealant  10  is pressed against the subfloor  4 , and the base portion  102  of the closet flange is bolted to the subfloor  4 , preferably with bolts  14  that pass through the layer of sealant  10 , as seen in  FIG. 1 . The sealant dam  12 , if present, prevents sealant between the subfloor  2  and the annular flange  108  from leaking through the hole  6  in the subfloor  2 . 
         [0040]    A second layer of sealant  16  is then applied to the upper surface of the annular flange  108  of the closet flange  100 . The impermeable flooring membrane  2  is then fastened to the second layer of sealant  16 . The impermeable flooring membrane  2  has a hole therethrough to allow connection between a drain of toilet  18  and the drain line. A third circular layer of a sealant  20  is then placed over the impermeable flooring membrane  2  around the hole through the impermeable sheet  2 . The impermeable sheet or membrane  2  is secured by cylindrical clamping ring  104  which fits over an upper cylindrical portion  106   b  of the cylindrical hub  106 . 
         [0041]    In certain embodiments, the base flange  108  extends radially from either the lower cylindrical portion  106   a  of the hub  106 , or from the upper cylindrical portion  106   b  of the hub. The upper and lower cylindrical portions of the hub may be coaxial, but are not required to be coaxial. In certain embodiments, the upper and lower cylindrical portions of the hub may be separated by an intermediate portion which is curved or bent so that the axis of the first cylindrical portion and the axis of the second cylindrical portion meet at an angle. In other embodiments, the upper and lower cylindrical portions of the hub may be separated by an S-shaped curved portion so that the upper and lower cylindrical portions are parallel to each other, but offset from each other. 
         [0042]    In certain embodiments in accordance with  FIG. 1 , the base flange  108  extends radially from the upper cylindrical portion  106   b  of the hub. The clamping ring  104  may be a cylindrical ring or tube  110  with a threaded inner surface  112  and an annular flange  114  extending from the lower end of the threaded cylindrical ring or tube  110 . In such embodiments, the threaded inner surface of the cylindrical tube is screwed onto a threaded outer surface  116  of at least the upper portion  106   b  of the cylindrical hub  106  of the closet flange  100  until the flange  114  of the clamping ring  104  contacts the third circular layer of sealant  20 . The impermeable sheet  2  is then secured between the lower annular flange  108  and the upper clamping ring  104 . The toilet  18  is then bolted to the closet flange  100 . 
         [0043]    The circular layer of sealant  20  between the impermeable flooring membrane  2 , such as a flooring cap sheet or tile membrane, and the clamping ring  104  of the closet flange  100  prevents water flowing over the impermeable layer  2  from traveling through the hole in the impermeable layer  2  and under the impermeable layer  2 . The circular layer of sealant  16  between the impermeable flooring membrane  2 , such as a flooring cap sheet or tile membrane, and the annular flange  108  of the closet flange  100  also prevents water which might penetrate a puncture in the impermeable layer  2  and flow under the impermeable layer  2  from reaching the hole  6  for the drainpipe  8  in the subfloor  4 . Thus, water cannot reach the hole for the toilet drain line, and leakage of water around the drain line is prevented. 
         [0044]    The base portion  102  of the closet flange  100  is seen in more detail in  FIG. 3  and  FIG. 3A . In certain embodiments, base portion  102  of the closet flange  100  has a cylindrical hub  106  with an annular flange  108  extending perpendicularly from the hub. In certain embodiments, hub  106  includes an upper portion  106   b  extending above the flange  108 , and a lower portion  106   a  extending below the flange  108 , as seen in  FIG. 3A . Above the flange  108 , the outer surface  116  of the upper portion  106   b  of hub  106  is threaded. The annular flange  108  may be circular, as seen in  FIG. 3 , or substantially quadrilateral, i.e., square, as seen in  FIG. 6 . Bolt-receiving holes  318  may be formed in annular flange  108 . Notches  320  to receive the heads of upwardly-directed bolts may be formed in the hub  106  of the base portion  102 . 
         [0045]    The base portion  102  seen in  FIG. 3  is used in a two-part closet flange  100  which also includes a clamping ring  104  as seen in  FIG. 4  and  FIG. 4A . The clamping ring  104  includes a cylindrical ring  110  with a threaded inner surface  112 , and an annular flange  114  extending therefrom. 
         [0046]    An alternate view of a closet flange seal made using the closet flange base portion of  FIG. 3  and the clamping ring of  FIG. 4  is shown in  FIG. 2 . A drain pipe  8  for a toilet passes through a hole  6  in a subfloor  4 . In certain embodiments, the outer surface of the drainpipe  8  is sealed to the inner surface of a cylindrical lower portion  106   a  of hub  106  of the closet flange, as seen in  FIG. 2 . In other embodiments, the inner surface of the drainpipe  8  is sealed to the outer surface of a hub  106  of the closet flange seal. The seal may be made by means of adhesively bonding or fusing the hub to the drainpipe, or by means of a gasket on the surface of the closet flange which seals to the surface of the drainpipe. A base flange  108  extends from the hub  106  of the closet flange  100 , perpendicularly to the axis of the closet flange  100 . This base flange  108  is positioned against the upper surface of the subfloor  4 , and bolted into place. A layer of sealant  16  is applied to the upper surface of the base flange  108 . The flooring membrane  2  is then secured to the upper surface of the base flange  108  by the sealant  16 . A second layer of sealant  20  is then applied to the upper surface of the flooring membrane  2 . The hub  106  of the closet flange extends above the base flange, forming an upper portion  106   b  with a threaded outer surface. 
         [0047]    The clamping ring  104  with a tube or ring  110  having a threaded inner surface  112  is then screwed onto the threaded portion of the hub, until the annular flange  114  of the clamping ring  104  contacts the second layer of sealant  20  on the upper surface of the flooring membrane  2 . Preferably, when clamping ring  104  is screwed into place, bolt-receiving notches  320  are exposed above the upper edge of tube or ring  110 , as seen in  FIG. 2 . Bolts  222  may then be positioned in bolt receiving notches  320 , and toilet  18  may be positioned on bolts  222 . If water is subsequently spilled on the flooring membrane  2 , it will then flow over the flooring membrane  2  and base flange  108  until it contacts the second sealant layer  20 , and then around the space defined by the sealant layer. Water will not flow under or through the base flange or through the hole in the subfloor. 
         [0048]    Further embodiments of the invention make use of a mounting ring assembly  500 , seen in  FIGS. 5 and 6 . The mounting ring assembly  500  has a tubular member  510  having a predetermined height which is generally from 0.5 to 2.5 inches. It has a top end, a bottom end, and an annular flange  520  extending radially outwardly from the top end of the tubular member  510 . A base plate  530  also extends perpendicularly from the outer surface of tubular member  510  and it is located a predetermined height above the bottom end of the tubular member  510 . In certain embodiments, the bottom surface of the base plate  530  is from 0.25 to 1.5 inches from the top surface of the annular flange  520 ; this distance is designated by the letter H. The distance between the bottom surface of the base plate and the bottom end of the tubular member is designated by the letter h. The plate  3  has four bolt-receiving holes  540  at the corners of the substantially square base plate, and bolt receiving holes  550  at the front and rear edges, as seen in  FIG. 6 . 
         [0049]    The top surface of the annular flange has a plurality of open ended slot assemblies  610  extending radially therefrom. In general, the mounting ring assembly  500  is designed to be placed in an aperture that has been cut in a subfloor, which may be made from corrugated steel, concrete, or wood, so that the bottom end of tubular member  510  telescopically fits with a drain pipe passing through the subfloor. A concrete floor is then poured over the subfloor until the top surface of the concrete floor is level with the upper end of the mounting ring assembly  500 , burying the base plate  530  of the mounting ring assembly  500 . The base of a toilet bowl is secured to the top surface of the annular flange  520  by a plurality of bolts extending upwardly from the open ended slot assemblies  610 , each bolt having a shank portion and a head portion. Nuts are used to tighten the base of the toilet bowl in position. 
         [0050]    The flange  500  may be modified to produce a flange  500 ′ for use in the current application by reshaping the substantially square base plate  530  of a flange  500  so that it is a substantially quadrilateral base plate  530 ′, as shown in  FIG. 7 . This may be done by cutting the base plate  530  along lines A and B, as shown in  FIG. 6 , to produce quadrilateral base plate  530 ′, as shown in  FIG. 7 . If desired, the ends of open ended slot assemblies  610  may be made flush with the outer edge of annular flange  520  by cutting along lines C, tangential to flange  520 , as shown in  FIG. 6 . Unlike the flange  500 , the flange  500 ′ as modified for use in the current application is designed so that the quadrilateral base plate  530 ′ fits directly into the bottom of the toilet  18 , as shown in  FIG. 9 , rather than being, positioned under a concrete layer. The shape of the substantially quadrilateral base plate  530 ′ may be designed to match the shape of the toilet  18 . If the sides of the base of the toilet  18  taper in a direction from a wide rear end to a narrow front end, the substantially quadrilateral base plate  530 ′ may be an Isosceles trapezoid, as seen in  FIG. 7 . If the sides of the base of the toilet are substantially parallel, the substantially quadrilateral base plate  530 ′ may be rectangular, as seen in  FIG. 11 . Although the description provided has described the shape of the base plate in terms of modifying an existing base plate, the base plate  530 ′ may be provided by molding a flange having the desired shape directly, without modifying an existing article. 
         [0051]    The substantially quadrilateral base plate  530 ′ of the modified flange  500 ′ is positioned on a wood, steel, or concrete subfloor  4 , with the bottom end of the tubular member  510  extending into a hole  6  for a toilet drainpipe  8 , as shown in  FIG. 10 . The outer surface of the drainpipe  8  is sealed to the inner surface of the bottom end of the tubular member  510  of the modified flange  500 ′. Substantially quadrilateral base plate  530 ′ extends from the hub or tubular member  510  of the closet flange  500 ′, perpendicularly to the axis of the closet flange  500 ′, and is positioned against the upper surface of the subfloor  4 , and bolted into place (bolts not shown for reasons of clarity). A layer of sealant  16  is applied to the upper surface of the quadrilateral plate  530 ′. A flooring membrane  2  is then secured to the upper surface of the substantially quadrilateral base plate  530 ′ by the sealant  16 . 
         [0052]    As seen in  FIG. 10 , a second circular layer of sealant  20  is then applied to the upper surface of the flooring membrane  2  over the quadrilateral plate  530 ′. The tubular hub  510  of the modified flange  500 ′ extends above the quadrilateral plate  530 ′. A clamping ring  800  is then positioned around tubular hub  510  over the second layer of sealant  20  on the flooring membrane  2 . 
         [0053]    Referring now to  FIG. 8 , the clamping ring  800  may have a substantially quadrilateral shape, which may match the shape of base plate  530 ′; alternatively, clamping ring  800  may have a circular shape. The clamping ring  800  has a hole  810  through the entire thickness of ring  800  to accommodate the tubular member  510  of modified flange  500 ′. The inner edge of the clamping ring  800  may have cutout notches  820  designed to accommodate the radially extending open ended slot assemblies  610  on the upper surface of the annular flange  520  extending perpendicularly from the top end of the tubular member  510 . In certain embodiments, the ends of open ended slot assemblies  610  have been made flush with the outer edge of annular flange  520  of flange  500 ′, as discussed above with regard to  FIG. 6 ; in such a case, cutout notches  820  in clamping ring  800  are unnecessary. Bolt-receiving holes  830  in clamping ring  800  are positioned so as to coincide with bolt-receiving holes  550  at in modified flange  500 ′. 
         [0054]    Returning to  FIG. 10 , the clamping ring  800  is positioned over the quadrilateral base plate  530 ′ extending from the tubular member  510  so that the clamping ring  800  contacts the second layer of sealant  20  on the upper surface of the flooring membrane  2 . If open ended slot assemblies  610  are present on annular flange  520 , clamping ring  800  may have cutout notches  820  designed to accommodate the radially extending open ended slot assemblies  610 . If open ended slot assemblies  610  are absent on annular flange  520 , or have ends which are flush with the edge of annular flange  520 , cutout notches  820  are not required on clamping ring  800 . The clamping ring  800  is then bolted to the subfloor  4  by driving bolts through holes  830  in the clamping ring and through corresponding holes  550  in the quadrilateral base plate  530 ′ of the modified flange  500 ′ into the wood, steel or concrete subfloor  4 . 
         [0055]    A toilet  18  is then positioned over the modified flange  500 ′ so that the outlet of the toilet (not shown in  FIG. 10 ) fits telescopically into the tubular member  510  of the modified flange  500 ′ and the substantially quadrilateral base plate  530 ′ of the flange  500 ′ fits into the bottom of the toilet  18 . This allows water to flow from the toilet to drain pipe  8  in the direction of arrow W, as seen in  FIG. 10 . The toilet  18  may be positioned over the flange  500 ′ by driving bolts through holes in the base of the toilet and through corresponding holes in the clamping ring and the quadrilateral base plate of the modified flange into the concrete subfloor. Alternatively, heads  1004  of upwardly directed bolts  1002  may be positioned in the radially extending open ended slot assemblies  610  on the upper surface of the annular flange  520  of the modified flange  500 ′, as seen in  FIG. 10 . The toilet  18  is then positioned over the modified flange  500 ′ so that the outlet of the toilet fits telescopically into the tubular member  510  of the modified flange  500 ′ and the upwardly directed bolts  1002  extending from the radially extending open ended slot assemblies  610  fit through holes in the base of the toilet  18 . The substantially quadrilateral base plate  530 ′ of the flange  500 ′ also fits into the bottom of the toilet  18  so that the edges of the base of the toilet fit flush against the subfloor  4 . Nuts  1006  may then be screwed onto the upwardly extending bolts  1002  to fit the toilet securely in position. 
         [0056]      FIG. 11  shows a further embodiment of the closet flange of the current invention, including a base flange  1100  and a clamping ring  1102 . The base flange  1100  has a cylindrical hub  1104  with an annular flange  1106  extending perpendicularly from the hub  1104 , as seen in  FIG. 11  from the side and  FIG. 11B  from above. In certain embodiments, the cylindrical hub  1104  has an inner diameter such that the cylindrical hub may slide telescopically over a drain pipe, where the drain pipe has an outer diameter of, for example, 3 inches or 4 inches. In certain embodiments, the cylindrical hub  1104  has an outer diameter such that the cylindrical hub may slide telescopically into a drain pipe, which may be, for example, 3-inch diameter pipe or 4-inch diameter pipe. In certain embodiments, the cylindrical hub may be connected to either 3-inch diameter pipe or 4-inch diameter pipe; in such embodiments, the cylindrical hub  1104  has an outer diameter such that the cylindrical hub may slide telescopically into 4-inch diameter pipe; and an inner diameter such that the cylindrical hub may slide telescopically over 3-inch diameter pipe. Above the flange  1106 , the outer surface of the hub  1104  includes threading  1108 . Notches  1110  to receive the heads of upwardly-directed bolts may be formed in the hub  1104  of the base flange  1100 , as seen in  FIG. 11B . The annular flange  1106  may be substantially quadrilateral, shaped to fit into the base of the toilet. In the embodiment of  FIG. 11B , the annular flange  1106  is substantially rectangular. The clamping ring  1102  includes a cylindrical ring  1112  with threading  1114  on its inner surface, and an annular flange  1116  extending outwardly from a lower edge of ring  1112 , as shown in  FIGS. 11 and 11A . The threaded inner surface of the clamping ring  1102  may be screwed onto the threaded outer surface of the hub  1104  of the base flange  1100 . As seen in the view from below in  FIG. 11C , the base flange  1100  may have two annular recesses  1118  and  1120  on the lower surface. An inner annular recess is  1118  is positioned adjacent to or in proximity to the hub  1104 , and is designed to receive a closed cell foam gasket  1122 , as seen in  FIG. 11 , or an elastomeric gasket. An outer annular recess  1120  is designed to receive a layer of sealant. 
         [0057]      FIG. 12  shows use of the closet flange of  FIG. 11  in new construction. A drain pipe  1200  for a toilet passes through a hole in a subfloor  1204 . The outer surface of the drainpipe is sealed to the inner surface of the hub  1104  of the closet flange  1100 . The annular flange  1106  of the base flange  1100  of the closet flange is positioned against the upper surface of the subfloor  1204 , and bolted into place with bolts  1206 . The inner annular recess  1118  (not shown in  FIG. 12 ) of the annular flange  1106  of base flange  1100  contains a closed cell foam gasket  1122  or an elastomeric gasket which is pressed against the subfloor as a sealant dam. A layer of sealant  1208  is applied to the upper surface of the annular flange  1106 . The flooring membrane  1210  is then secured to the upper surface of the annular flange  1106  by the sealant  1208 . In the event sealant leaks under the annular flange  1106 , the sealant dam  1122  prevents it from leaking through the hole  1202  in the subfloor  1204 . 
         [0058]    A second layer of sealant  1212  is then applied to the upper surface of the flooring membrane  1210 . The threaded cylindrical ring  1112  of the clamping ring  1102  is then screwed onto the threading  1108  on the hub  1104 , until the annular flange  1116  of the clamping ring  1102  contacts the second layer of sealant  1212  on the upper surface of the flooring membrane  1210 . If water is subsequently spilled on the flooring membrane, it will then flow over the base flange until it contacts the second sealant layer, and then around the space defined by the sealant layer. Water will not flow under or through the base flange or through the hole in the subfloor. 
         [0059]      FIG. 13  shows retrofitting of the closet flange of  FIG. 11  to existing construction having a finished floor  1300  on top of a subfloor  1204 . A drain pipe  1200  for a toilet passes through a hole  1202  in a subfloor  1204 . A closet flange including a base flange  1100  with a cylindrical hub  1104  fits onto the existing drain pipe by sliding telescopically over the existing drainpipe or into the existing drainpipe, depending on drainpipe diameter. The annular flange  1106  of the base flange  1100  of the closet flange is positioned against the upper surface of the finished floor  1300 , and bolted into place with bolts  1206 . The annular flange  1106  contains two annular recesses on its lower surface (not shown in  FIG. 13 ). The inner annular recess  1118  of the annular flange  1106  of base flange  1100  contains a closed cell foam gasket  1122  or an elastomeric gasket which is pressed against the floor as a sealant dam. The sealant dam may also be made of wax. The outer annular recess  1120  of the annular flange  1106  of base flange  1100  contains a sealant layer  1302  which is pressed against the floor  1300 ; the sealant dam  1122  prevents sealant from entering the hole  1202  in the subfloor  1204 . The threaded cylindrical ring of the clamping ring  1102  (not shown in  FIG. 13 ) may then be screwed onto the threaded portion of the hub, until the annular flange of the clamping ring contacts the base flange; however, it is not required for a retrofit installation. However, if new flooring is ever installed, the clamping ring  1102  may be used to clamp the new flooring against the base flange. Therefore, screwing the clamping ring  1102  onto the hub  1104  and saving it for future use is advisable. 
         [0060]      FIG. 14  shows an alternate compression closet flange for installation on top of a drain pipe. This may be done in either new construction, or in a retrofit assembly. The closet flange includes a base flange  1400  having an optionally threaded upper portion with cylindrical hub  1402 , and an annular flange  1404  extending radially outward from the cylindrical hub  1402  midway between the upper and lower ends of the cylindrical hub  1402 . The annular flange  1404  has openings  1406  therein for receiving bolts. A lower end of the cylindrical hub  1402  has a recessed area  1408  for receiving an upper end of a lower section  1410  which fits telescopically inside the cylindrical hub. A lower end of the lower section  1410  has a lip  1412  for seating a cylindrical seal  1414 , the lip having an outer diameter. The outer diameter of the lip is substantially the same as the outside diameter of the cylindrical hub  1402 . 
         [0061]    The annular flange  1404  has, on its lower surface, at least one and preferably two annular recesses  1416 . Each annular recess  1416  is adapted to contain a sealant darn or a layer of sealant to be pressed against a floor surface. In some embodiments, the annular flange  1416  contains an inner annular recess and an outer annular recess. The inner annular recess of the annular flange contains a closed cell foam gasket or an elastomeric gasket which is pressed against the floor as a sealant dam. The outer annular recess of the annular flange contains a sealant layer which is pressed against the floor; the sealant dam prevents sealant from entering the hole in the subfloor. 
         [0062]    Cylindrical bores  1420   a  and  1420   b  run through the cylindrical hub  1402  and through a wall of the lower section  1410 . Bolts  1422  run through these cylindrical bores and through nonrotatable nuts  1424  in the lower section, so that the heads of the bolts may be accessed from the upper end of the cylindrical hub  1402  and tightened. After positioning the cylindrical hub telescopically inside a drainpipe  1426 , tightening these bolts  1422  draws the lower section  1410  upward toward the cylindrical hub  1402 . 
         [0063]    The cylindrical seal  1414  is seated between the cylindrical hub  1402  and the lower section  1410 . The cylindrical seal is made of rubber or another elastomer. As the lower section is drawn upward toward the cylindrical hub, the cylindrical seal  1414  is compressed and expands outwardly toward the inner surface of the drainpipe  1426 , thereby providing a compression fit between the cylindrical seal  1414  and the inside of the drainpipe  1426 . In new construction, a flooring membrane may then be positioned over flange  220 , and a clamping ring  1430  may then be screwed or bolted onto the upper portion of the cylindrical hub to clamp the flooring membrane between flange  1404  and the clamping ring  1430 . 
         [0064]    In certain embodiments, the cylindrical seal is seated between the cylindrical hub and the lower section, and is facing an inner surface of the cylindrical hub and the lower section. In such embodiments, the inner surface of the cylindrical hub fits telescopically over the outer surface of the drainpipe. As the lower section is drawn upward toward the cylindrical hub, the cylindrical seal is compressed and expands inwardly toward the outer surface of the drainpipe, thereby providing a compression fit between the cylindrical seal and the outside of the drainpipe. 
         [0065]    In other embodiments, a first cylindrical seal is seated between the cylindrical hub and the lower section, and is facing an inner surface of the cylindrical hub and the lower section; and a second cylindrical seal is seated between the cylindrical hub and the lower section, and is facing an outer surface of the cylindrical hub and the lower section. As the lower section is drawn upward toward the cylindrical hub, both cylindrical seals are compressed and expand. In such embodiments, the user may elect to fit the inner surface of the cylindrical hub telescopically over the outer surface of the drainpipe; or to fit the outer surface of the cylindrical hub telescopically over the inner surface of the drainpipe. 
         [0066]    As seen in  FIG. 15 , various embodiments of the invention use a two-part closet flange  1500  to provide an improved seal between a floor and a closet flange. Flange  1500  comprises a base portion with a hub portion  1508  and a annular base flange  1506  extending from the hub; and a clamping ring  1502 . An impermeable floor covering  1504  may be positioned between base flange  1506  and clamping ring  1502 . A cylindrical portion  1510  of clamping ring  1502  extends telescopically into hub portion  1508  of flange  1500 . 
         [0067]    The upper surface of annular base flange  1506  comprises at least two notches  1518  adapted to receive the heads of bolts  1512 . Notches  1518  may be radially directed straight notches, or curved notches as shown in  FIG. 15 . Bolts  1512  are used to secure a toilet to flange  1500 . Bolts  1512  may come equipped with washers  1514  and bolt  1516 . 
         [0068]      FIG. 16  shows an exploded view of the two-part closet flange of  FIG. 15 , in conjunction with a drainpipe  1608 . Drainpipe  1608  fits telescopically into the lower end of hub portion  1508 . The upper portion of hub  1508  includes an inner surface  1604 . Cylindrical portion  1510  of clamping ring  1502  is then connected to surface  1604  of hub  1508  so that floor covering  1504  is sandwiched between clamping ring  1502  and annular flange  1506 . In some embodiments, threading  1602  on the outer surface of cylindrical portion  1510  of clamping ring  1502  mates with threading  1606  on inner surface  1604  of hub  1508 , allowing cylindrical portion  1510  to be screwed into surface  1604 . In other embodiments, the outer surface of cylindrical portion  1510  of clamping ring  1502  and inner surface  1604  are not threaded; instead, surface  1604  and cylindrical portion  1510  slide together telescopically, and are adhesively connected. 
         [0069]    Although the various exemplary embodiments have been described in detail with particular reference to certain exemplary aspects thereof, it should be understood that the invention is capable of other embodiments and its details are capable of modifications in various obvious respects. As is readily apparent to those skilled in the art, variations and modifications can be affected while remaining within the spirit and scope of the invention. Accordingly, the foregoing disclosure, description, and figures are for illustrative purposes only and do not in any way limit the invention, which is defined only by the claims.

Summary:
An improved method of installing a closet flange allows installation of plumbing fixtures with a reduced likelihood of leaks. The method involves telescopically fitting an inner or outer surface of a drainpipe to a surface of a cylindrical portion of a hub of a closet flange, where the hub has a base flange extending therefrom; and securing the base flange against the upper surface of a subfloor. A first layer of sealant is applied to an upper surface of the base flange; and a flooring membrane is secured to the upper surface of the base flange by the first layer of sealant. A second layer of sealant is applied to an upper surface of the flooring membrane; and the upper surface of the flooring membrane is clamped between the base flange and a clamping ring. The method may be performed using a two-part closet flange for connection to a drain pipe for a toilet. The two-part closet flange comprises a cylindrical hub adapted to telescopically connect to the drain pipe; an annular flange radially extending from the cylindrical hub; a clamping ring; and a means to clamp a flooring membrane between the clamping ring and the annular flange.