Field of the Invention

The invention pertains to devices for use in plumbing installations.

Background of the Invention

In the residential construction industry, it is common practice to rough in the drainage in the basement floor for use in the event that the homeowner later wishes to install a plumbing fixture in the basement. This roughing-in involves laying a drainpipe in the dirt floor connected to the drainage system and affixing a vertically-extending pipe at its end before pouring the concrete slab. In modern basement floor construction, a vapor barrier film may be provided under the concrete slab to seal the floor and in particular to prevent radon gas in the ground from entering the basement. The vapor barrier film is laid on the dirt, is sealed to the vertically-extending pipe, and the concrete slab is poured on top of the film. The vertical pipe protrudes above the concrete slab and shows the location of the drain pipe when it is later needed. Although this marking of the location of the drain is of assistance, in order to use the drain the plumber has to break up the concrete slab around the vertical pipe, dig around the drain pipe and install a trap on the drain pipe before attaching a bathtub or other plumbing fixture to the drain. This operation requires substantial labor and punctures the vapor barrier film. It is difficult to re-seal the film, with the result that the vapor barrier seal may be broken and gases in the ground may leak into the basement. It is known in the construction industry that a tub box can be used to enclose a drain trap in a concrete slab floor, in order to facilitate connection of the plumbing fixture to a drainage line. Examples in the patent literature are Logsdon, US 3,593,344, and King, US 6,264,056.

Summary of the Invention The invention provides a tub box for use in enclosing an end of a drain pipe in a concrete slab floor of the type having a concrete slab and a vapor barrier film, and permitting a plumbing connection to the drain pipe while maintaining a secure seal to the vapor barrier film. The tub box comprises a container having side walls, a closed bottom and a top edge defining an open top, the top being adapted to receive a removable lid, and a radially outwardly-protruding flange on the side walls, axially spaced below the top edge by a distance approximately equal to the thickness of the concrete slab, for sealing attachment to the vapor barrier film.

The invention further provides a method of enclosing an end of a drain pipe in a concrete slab floor of the type having a concrete slab and a vapor barrier film, and permitting a plumbing connection to the drain pipe. A container is provided having side walls, a closed bottom, a top edge defining an open top, the top being adapted to receive a lid, an opening in the container to receive an end of the drain pipe, and a radially outwardly- protruding flange on the side walls, axially spaced a distance below the top edge. The container is placed in the ground on which the concrete slab is to be poured, with the flange at the surface of the ground and the drain pipe extending into the container interior through the opening. The vapor barrier film is laid on the ground surface and is sealed to the flange. The concrete slab is poured on the ground over the vapor barrier film to a thickness approximately equal to the axial distance between the flange and the top edge of the container. A removable lid is placed on the container. Further aspects of the invention and features of specific embodiments of the invention are described below.

Brief Description of the Drawings

Figure 1 is a vertical cross-sectional view through an embodiment of the tub box as installed in a concrete slab floor.

Figure 2 is an isometric view of the tub box of Figure 1.

Detailed Description of the Preferred Embodiments

The tub box 20 is made for use with a concrete slab floor in which, during building construction, a concrete slab is laid on the ground of the basement, with a drain pipe buried in the ground under the slab and connected to the drainage system, and a vapor barrier film is employed.

The tub box 20 comprises a container made of impermeable, high- impact plastic, for example ABS, by injection or blow molding. It has four side walls 22 and a bottom wall 24, and is open at the top 26. At the top edge 28, a radially-outwardly extending ledge 30 is provided, to receive a lid 32. The ledge has a horizontal section 34 to support the lid, and a vertical section 36 which forms a perimeter within which the lid fits.

A flange 40 protrudes radially outwardly from the sidewalls. The flange is spaced between the top edge and the bottom of the container, and more specifically is positioned axially downward from the top edge by a distance D which is approximately equal to the thickness of the concrete slab 42 in which the container is to be embedded, as explained below. The container has an opening 44 in one side wall 22 below the level of the flange 40, sized to receive the end of the drain pipe 46. The opening 44 may be made at the time of manufacture of the container or be drilled in the side wall at the time of installation, for convenient alignment with the drain pipe. Alternatively, the opening 44 may be in, or be made in, the bottom of the container rather than the side wall, depending upon the requirements and preferences for the installation.

The container may be of any size that is suitable for a particular installation. An exemplary size is 16 inches (40.6 cm) high, 14 inches (35.6 cm) long and 12 inches (30.5 cm) wide, the length and width being measured at the top of the side walls, tapering to 13 inches (33 cm) long and 11 inches (28 cm) at the bottom. The ledge may have a width of 5/8 inches (1.6 cm) and a height of 5/8 inches (1.6 cm). The distance D may be about 4 inches (10 cm). The container 20 is installed in the basement floor during building construction in the following manner. The container is placed in a dug-out hole in the dirt 48, with the end 50 of the drain pipe 46 extending through the opening into the interior of the container. Dirt is filled in around the container, to about the level of the flange. A rubber sealing boot 52 is put over the pipe end 50, to form an impermeable seal between the side wall 22 of the box and the pipe 46. An end cap 54 is put on the end of the pipe. A vapor barrier film 56 is laid on the dirt floor and is sealed to the box by applying a bead of adhesive 58 to the upper surface 60 of the flange and pressing the film against it. The lid 32 is put on the container and the concrete slab 42 is then poured on top of the film to a thickness about equal to the distance D from the flange to the top edge of the container. The installation thus provides a visual indication on the concrete slab floor, namely the lid of the box, as to the location of the drain pipe, and provides a complete seal with the film, i.e. by virtue of the seal to the flange and the seal around the side wall opening. The seals are not broken when a plumbing fixture is subsequently connected to the drain pipe.

To use the installation, the lid is lifted off, the end cap is removed, and a conventional drain trap is attached to the open end of the drain pipe, within the tub box 20. A plumbing fixture, such as a bathtub, is then connected to the trap.

As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the scope thereof. As one example, the flange can be any shape which permits sealing attachment of the vapor barrier film to the container. As another example, the top edge of the container can be plain with no ledge, and the lid can be placed on top of and overhanging the top edge. As a further example, the tub box may be round in horizontal cross-section, rather than rectangular as illustrated. Accordingly, the scope of the invention is to be construed in accordance with the following claims.