US3864760A

US3864760A - Bathing facility

Info

Publication number: US3864760A
Application number: US247795A
Authority: US
Inventors: Duane C Bowen
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-04-26
Filing date: 1972-04-26
Publication date: 1975-02-11
Anticipated expiration: 1992-02-11

Abstract

A translucent, bendable, sawable, fiber-reinforced plastic sheet is fitted between the rail of a sliding closure, for a recessed tub or shower, and the ceiling or sidewall. When extended horizontally to the wall, the sheet is domed for self-support.

Description

[ 1 Feb. 11, 1975 Bowen [54] BATHING FACILITY 3,007,178 11/1961 Altman et al. 4/161 3,0l0.ll6 ll I961 C l [76] Inventor: Duane c. Bowen, 2290 Nob Hm 110L485 Q1963 fil ii DR, Carlsbad Cflllf- 92008 3,467,968 9/l969 Munchisa Tatii 4/148 [221 Film P 26, 1972 FORElGN PATENTS OR APPLICATIONS [21] App]. No.: 247,795 228.42) l2/l962 Austria 4/l4o 52 us. Cl. 4/146, 4/148 Primary -Y Hflmsby 51] rm. (:1 A47k 3/22 41mm?" Firm-Duane [58] Field of Search 4/145, 146, 148, 149, 164,

4/16] [57] ABSTRACT A translucent, bendable, sawable, fiber-reinforced [56] References cued plastic sheet is fitted between the rail of a sliding clo- UNITED STATES PATENTS sure, for a recessed tub or shower, and the ceiling or l.639,705 8/l927 Schmiedeknecht 4/l45 idewall. When extended horizontally to the wall, the 2,374,490 4/1945 Lehman 4/148 X heet is domed for selflsupport 2,424,537 7/l947 Aronheim... 2,756,438 7/1956 Soberman 4/149 15 Claims, 7 Drawing Figures W 2 l8 l8 PATENTEB FEB 1 1 I975 SHEET 2 OF 2 BATHING FACILITY BRIEF SUMMARY OF THE INVENTION AND OBJECTIVES My invention, in general, concerns means preventing loss of heat, from a recessed tub or shower, over the rail supporting a sliding closure for the bathing facility.

Warm water used in a tub or shower tends to heat the air to a temperature more comfortable to the bather than the temperature of the remainder of the air in a bathroom. This warmed air is lost, however, in the common type of bathing facility. due to loss over the rail of the sliding closure for the facility. due to the tendency of heated air to rise to the top of an enclosure. If the air were confined to the area immediately above the bathing facility, to the ceiling level or lower, then the complete volume of air would be, relatively, comfortably warmed by the warm water, particularly in the case of a bather who likes a longer bath or shower. Confinement of the air over the bathing facility will also reduce escape of water-laden air into the remainder of the bathroom and will reduce steaming of mirrors, etc. This does not apply, of course, to types of shower stalls, with tops, completely recessed into walls. It applies, rather, to the common type of bathing facility which is a tub, shower, or combination tub-shower which is fitted between two (full or stub) walls of a bathroom and abutted to a third wall, the walls being the same height as other walls in the bathroom, and the facility being closed by sliding or accordian doors supported by a rail some distance below the ceiling.

To an extent this type of bathing facility has a limited range of standard lengths and widths. A currently popular bathing facility of this type is molded as one piece out of fiber-reinforced plastic which extends partway up the walls on three sides, and these tend to be of rather standard dimensions. However, these facilities are not necessarily standard in dimensions within fractions of inches, even those of the same nominal dimensions. Tolerances in framing or finishing of a room are rather broad, because of the materials used, methods of fabrication, and expected skills of workers. Therefore, means to confine air above a bathing facility, to be manufactured and supplied rather than to be fabricated on the site from raw materials, should be adaptable to generous tolerances in dimensions and preferably, to some differences in nominal dimensions, so that a minimum number of sizes can be manufactured and yet fit most facilities of present or recent manufacture. I have designed a structure (made from sawable plastic) that can be trimmed to adjust to tolerances or differences in dimensions, both for new construction and for existing installations (which preferably can be modified by the householder within his expected skills and within the limits of simple tools found in most households). Further, I prefer a bendable plastic construction so that, if domed only transversely, it can be partly adjusted in width by bending.

It is a desirable not to substantially interfere with normal light available to a bathing facility so I have designed a structure using a translucent material. In fact, some people may prefer more light in a bathing facility or other people may want an infrared heating source for the bathing facility. Either type of electrical radiation source can be provided because, in one configuration, I provide, in effect, a lowered ceiling or shield which, through the use of translucent material or even a transparent inset, can provide a suitable mount for an electrical source electrically shielded or insulated from the volume of the bathing facility open to water (which is of special importance with a shower).

There can be a height problem, particularly for a taller person or particularly in the case of lower rails, so I have devised a domed structure in one configuration which not only provides head room but also, by its arced construction, provides a self-supporting structure with sheet material that would sag if supported in horizontal disposition. As observed above, a sheet domed in one direction can also adjust width in that direction.

The objects of my invention include (a) to devise means to solve the above-recited problems, to achieve the above-reviewed desirable results, and to provide the above-reviewed features, (b) to confine heated and moisture-laden air to the volume immediately above a bathing facility, (c) to best adapt to the tolerances and ranges of dimensions of standard bathing facilities of the described types, (d) to provide a structure that can be a factory produced article and may be readily installed by a carpenter or a householder, (e) to devise such means not interfering with normal bathing facility lighting, or to provide additional lighting, or to provide radiation heating, (f) to provide suitable height and structural strength, and (g) to provide the above at a cost acceptable to the builder or to the householder as new equipment or a modification, and to devise such structure of suitable appearance.

My invention will be best understood, together with additional objectives and advantages thereof, from the following description, read with reference to the drawings, in which:

FIG. 1 is a side view of a specific embodiment of a bathing facility constructed in accordance with my invention.

FIG. 2 is an enlarged end view, partly in section, taken on line 2-2 of FIG. 1.

FIG. 3 is a view like that of FIG. 2 only on enlarged scale (and broken) to better show the details of construction.

FIG. 4 is a plan view.

FIG. 5 is an end view, partly in section, of a modified form of my invention.

FIG. 6 is a partial side view of the construction shown in FIG. 5.

FIG. 7 is a view of a construction generally like that of FIGS. 1-4 but modified in certain respects.

A bathing facility 10 is shown in FIG. 1, which is indicated to be a shower because of the length of doors l2 and the short distance from the bottom of the doors to the floor 14. It will be apparent from the following description, however, that the invention applies equally to a tub or a tub-shower combination. Bathing facility 10 is of the type installed in a bathroom by being'titted up against one wall 16 and between two full or stub walls 18, and of the type spaced below ceiling 20 (the ceiling over the bathing facility being the same height as in the remainder of the bathroom). The sidewalls and ceiling above the facility (and in the remainder of the bathroom) are finished," i.e., covered with plaster board or other finish such as tile, etc. The closure is formed by sliding doors 12 or other closure means (such as an accordian door which can be opened and closed) which are supported by a rail 22 that is spaced below ceiling 20. Common dimensions includes an 8 feet ceiling, 74 inches to 76 inches to the top of rail 22, about 5 feet between walls 18, and 28 inches 33 inches from the front of the tub or shower to rear wall 16.

As explained before, heated, moisture-laden air escapes upward from bathing facility, over rail 22, into the remainder of the bathroom, thereby reducing the level of temperatures of air in the bathing facility compared with the temperatures the air would reach by heating by hot water used in tub or shower if the air were substantially confined, and, further, introducing more moisture into the remainder of the bathroom, to cloud mirrors, etc., than would be the case if the air were so confined. The comparative elevation of temperatures of air when confined to the volume of the bathing facility versus when not confined depends on factors such as the original temperature of air, the temperature of water used, the amount of water used, the length of the shower or bath, etc. However much difference in comfort the bather will sense will depend partly on the length of the shower or bath and the water temperature used. Those preferring short showers, or at least partly cold showers, may sense little if any difference in comfort, but experience with a prototype shows temperatures are considerably more comfortable for those preferring longer, warmer bathing. One reason a bather feels a chill, of course, is due to evaporation of water from his skin, and part of the increased comfort might be due to a lower evaporation rate when moisture-laden air is confined to the bathing facility, as compared to the evaporation rate to dryer air when air is not confined. Whatever the reason, air temperature, air moisture content, or reduced drafts (due to rising of heated air and replacement by cooler air), the invention produces more comfortable bathing at least for those persons enjoying longer bathing and higher water temperatures.

It is not known if this problem was unobvious and has not been sensed before, or whether, if sensed, an economical way to solve the problem could not be devised. The type of bathing facility shown in FIG. 1 is probably that which has been most frequently installed in new homes for some period of time. A substantial amount of expense would be incurred if the problem of air confinement in a bathing facility were to be solved by lowering the ceiling above the bathing facility to the height of rail 22, so that this might be done only in more expensive homes even if the desirability of air confinement were sensed. Sometimes shower stalls are recessed into walls, which can help in air confinement, but this does not appear to be as common a bathing facility as that shown in FIG. 1, and perhaps the reason is increased cost of bathroom fabrication, and, in any case, the recessed shower stall is not an acceptable substitute to many people for a bath or a shower-bath combination. A common form of bathing facility such as that shown in FIG. I, in current production, is one molded as one piece out of fiber-reinforced plastic, a factor taken into consideration in one form of my invention, as will appear later in this description.

When I comprehended the desirability of having air confinement means in a bathing facility of the type shown in FIG. 1, I devised the following requirements it was felt a solution would have to meet in order to be made available at a price that had general acceptance (not to add substantially to the cost of bathroom construction in new construction and to be economical in bathroom modification and in keeping with what persons might be able to afford or willing to pay for this improvement):

a. a construction of about minimum cost in terms of purchased items to achieve the objective,

b. a construction requiring no change to most bathing facilities of this type being sold,

c. minimum time for installation by carpenters in new construction,

d. minimum time and complexity for existing bathing facility modification by a carpenter or householder, including providing a construction that could be installed with only the tools that the average householder could be expected to have. and

e. adaptability to most bathing facilities of this type being sold in terms of common dimensions, so that the market could be supplied with a minimum number of sizes, taking into consideration both differing nominal dimensions and variations due to tolerances to be expected in construction of bathing facilities.

I elected to construct the enclosing means out of onepiece sheet material, as one integral article, except for any edge support needed, or except for any extra light or heat source (which is an optional addition, as hereaf- .ter described). By this I mean I excluded constructions which would have to be fabricated at the factory or on the site out of a number of pieces of material, because it would be quite economical to use a single sheet of material either flat or molded. Preferably the sheet material, especially when molded into a shape, is formed of fiber-reinforced plastic, as this material is both economical in flat condition and economical to mold. A number of fiber-reinforced plastics could be used, and suitable types include those types of fiber-reinforced plastics sold in flat sheets or corrugated for such purposes as patio roofs and the like. Selections of suitable fiber-reinforced plastics for the purpose will be obvious to those skilled in the art of manufacturing such sheets and molding the same. A plastic with sufficient strength without fiber reinforcement is to be regarded as an equivalent, but I believe the most economical, practical plastic materials will be fiber-reinforced. Another reason for selecting this type of material is that it usually can be cut with an ordinary saw, which means the material can be trimmed (as needed) to size by carpenter or householder. If curved in one direction, such plastics usually can be bent to some degree, another consideration in fitting to a bathing facility in certain circumstances. Another reason to prefer a fiber-reinforced plastic is that it can be made translucent, so as to not substantially interfere with normal direct or indirect lighting into the bathing facility, or adapted to transmit light or radiant energy if supplemental light or heat is provided.

In my preferred construction of FIGS. 1-4, I have elected to extend a curved sheet 30 generally horizontally, at rail height and above, from rail 22 to wall 16, and preferably this sheet is a translucent, sawable, bendable, fiber-reinforced plastic sheet. Note that adaptation to some difference in dimensions of widths from rail 22 to wall 16 can be accommodated by increased bending of sheet 30 and, obviously, it should be given a width considered maximum for bathing facilities of a more or less standard width so as to adapt to smaller dimensions by some increased upward bending. (It appears that bathing facilities formed as one piece out of fiber-reinforced plastic have a rather limited range of standard sizes, but this question was not extensively surveyed.) In the configuration shown in FIGS. 14, it is preferred that the sheet be molded to substantially the shape shown in the factory, but if a molding were attached to rail 22 (or if rail 22 were specially configured to receive the edge of a sheet) and if the same molding shown or preferably a specially configured molding to receive the opposite edge of sheet were attached to wall 16, it would be possible to use a sheet 30 that is normally flat but bendable under moderate manual force into a domed configuration. I prefer the pre-molded construction as it permits use of a standard rail (and does not require molding, clips, etc., to be fixedly secured to the rail). The upwardly arced configuration is preferred for self-support. It a flat. horizontally-disposed sheet were used, instead, a heavy weight sheet would have to be used to avoid unsightly sagging or a configured sheet would be needed such as one having corrugations or a waffle pattern, a honeycomb would be needed for strength, or horizontal stringer support means would be required. A second reason for an upward arc is for head room in some bathing facilities, i.e., some bathing facilities, particularly tub or tub-shower installations have a rail 22 too low for a tall person to stand in the facility under the level of the top of rail 22. If sheet is translucent, it will not interfere with normal bathroom direct or indirect lighting into the bathing facility.

Sheet 30 needs front and rear supports. I devised use of rail 22 for front support by providing a reverse bend 32 in the sheet (to abut the inside of rail 22) and by providing a flange 34 on the sheet to rest on the top of rail 22. This requires no modification of standard rails 22, and flange 34 does not have to be fixedly secured to the rail.

I provide a rear flange 36 on sheet 30. Any type of rest on rear wall 16 can be provided on rear wall 16 for flange 36. This could take the form of clips, but an L- shaped extrusion 38 (metal or plastic, secured by screws 40) with a flange against the wall and a horizontal flange to receive flange 36, and extending substantially the length of flange 36, will present a more finished appearance. Note that the use of flange 36 means that this flange can be readily sawed if needed to adjust width of sheet 30 to the distance between rail 22 and wall 16 (and preferably the width of sheet 30 is the maximum of the designed nominal dimension plus maximum expected tolerance, as the design is to trim excess width rather than to try to increase the width of the enclosing medium). One width of bathing facility observed in current manufacture was about 28 inches and another about 33 inches. Whereas flange trimming would be considerable for one size to accommodate both sizes, a sheet about 34 inches and a sheet about 30 inches could adapt to a wide range of dimensions, considering adaptation by bending and by trimming. Flange 36 could be given any desired width within a reasonable range, for the purpose of adaptation by trimming, i.e., as much as several inches.

I have mentioned, before, the current use ofonepiece fiber-reinforced plastic bathing facilities. Whereas at present it does not appear that these facilities commonly bring up the rear wall and end walls (they commonly have rear and end walls extending up the recess walls at least five feet or so) as high as or, if as high, even with rail 22, there is no reason that can not be done as such rear and end walls end in ledges (right angle bends to the wall and then terminating in upwardly extending flanges secured to studding and concealed behind the plasterboard finish of the bathroom) upon which sheet 30 could rest. At present, possibly the reason for not making the rail and the bathing facility walls at the same height may be they are commonly not manufactured by the same source. The appearance would be better ifthey had the same height, even in the absence of my invention, as a gap often needs to be filled at the upper end of the metal shower door jambs when the protruding plastic walls are short of the rail height. In any event, in the future it is possible that bathing facilities will be modified to provide their normal ledges at about the height of rail 22 so as to be usable to support sheet 30 at rear wall 16 (and also at side walls 18 in the FIG. 7 construction). A further possibility is to integrate sheet 30 into the plastic bathing facility construction if the walls had that height, in which case the side flange 36 (and the end flanges 50 in FIG. 7) could end in upright flanges to match the bathing facility construction which, as noted above, terminate in horizontal flanges to the wall and vertical flanges up the wall behind the usual plasterboard finish.

In my preferred construction of FIGS. 1-4, I do not provide supports for sheet 30 on end walls 18 and sheet 30 has the same arced transverse cross-section from end to end (although I do provide end supports, etc., in the FIG. 7 construction). This is consistent with several of the design parameters set forth above, i.e., economy of the manufactured sheet, minimum cost of installation, and adjustment to facility lengths and tolerances. Around 60 inches between walls 18 is rather standard in some facilities, but observe that a 66 inches long sheet 30 could accommodate a range of lengths (by trimming), i.e., 66 inches, 60 inches, 54 inches, etc. Sheet 30, thus, can be made such a length as to accommodate the maximum distance between walls 18 of a standard design or designs, and then sheet 30 can be trimmed as needed with a saw to fit actual dimension. Note that sheet 30 does not have to be exactly as long as the distance between walls 18, as some small air gap can be accepted, i.e., the top enclosure does not have to be air tight. Minimizing any air gap will provide a better appearance, but the possibility of trimming or of leaving a gap will accommodate any irregularity to walls 18, that may not be perfectly flat or parallel (if rail 22 and wall 16 are not exactly straight, flat or parallel, note also that the construction above described will accommodate irregularity and will do so without any sacrifice in appearance).

In FIG. 7, the sheet is molded with a flat or arced end wall 49 at each end terminating ni a (trimable) flange 50 which restson an L-shaped molding 52 (secured by screws 54) identical with molding 38 (and meeting the same by preferably beveled corners of the two extrusions). This will be provide a more finished appearance, and flanges 50 can still be trimmed to adjust to distance between walls 18. The FIG. 7 construction will be used if a better appearance is desired at additional cost.

I realized that sheet 30 provides means for mounting an incandescent or fluorescent light or a radiant heater (preferably infrared bulbs) 60 for the bathing facility, particularly in that the plastic sheet insulates electrical parts from the source of water, pipes, etc. which whould be a particularly important safety consideration in the case of a shower. Although I have shown sheet 30 as not needing to be fixedly secured, for safety rea sons it may be desirable to

secured flanges

34, 36 and 50 by screws to their supporting surfaces so there is a fixed barrier between the electrical source and the area of water. An electrical conduit 62 and plug 64 are shown (for connection to an outlet) merely to illustrate electrical connection to an outlet, although permanent wiring could be used. it is assumed for the present purposes that the light or heater 60 can be housed in a box secured to sheet 30 by fasteners to box flanges 66 and the plastic sheet 30 will be a satisfactory translucent medium for transmission of visible or infrared radiation. If it is deemed preferable to provide a glass inset in an opening in sheet 30, such a provision will be a simple matter within the skill of designers in the art, but such construction would add to cost.

There is another practical and economical way to complete the enclosure of the bathing facility shown in FIGS. and 6 which, although increasing the volume of air to be heated during bathing, does prevent air passing over rail 22. in this construction a flat sheet 70 extends between rail 22 and ceiling 20. Upper and lower extrusions 72 have grooves 74 accepting the edges of sheet 70 and have flanges 75 for securing the same to rail 22 and ceiling by screws 76. For best appearance, if the top of rail 22 is curved, the lower molding 72 would have a curved lower surface. Note that the distances between ceiling 20 and rail 22 are not standard, but this can be readily accommodated by trimming if a sawable fiber-reinforced plastic sheet is used, which is preferred. Likewise, the distance be tween end walls 18 can be accommodated by trimming of sheet 70. End moldings do not have to be provided, sheet 70 does not have to exactly meet end walls 18, with substantially the same considerations involved as to whether the FIGS. 1-4 or FIG. 7 contruction should be used, balancing a more finished appearance against additional cost. Sheet 70 could be glass (it being desirable translucent plastic or glass be used so as to not reduce lighting into the bathing facility), this being a choice involving possible matching of the translucent panels of sliding doors 12, relative cost of plastic and glass, relative cost of cutting glass to adjust to length and width versus sawing plastic, etc.

Having thus described my invention, I dont want to be understood as limiting myself to the precise details of construction shown but instead want to cover those modifications thereof that will occur to those skilled in the art after learning of my invention and which are fairly within the scope of my invention.

I claim:

1. An improvement in the combination of a bathroom and a bathing facility positioned therein, said facility being fitted between first and second parallel vertical end wall surfaces and a third vertical side wall surface meeting said first and second wall surfaces at right angles and a horizontal ceiling wall surface above said facility, said wall surfaces above said bathing facility being finished, and there being a horizontally slidable closure on the side of the facility opposite to said third wall surface extending between said first and second wall surfaces and which can be opened for access to said facility, said closure being supported from a top horizontal rail extending between said first and second wall surfaces and spaced below said ceiling surface, said improvement being means to substantially prevent passage of heated and moist air between said rail and said ceiling surface from said bathing facility into said bathroom when said closure is extended between said first and second walls, said means comprising and elongated sheet-like body with two parallel elongated side edges and two parallel transverse edges substantially bridging the space between said rail, said first and second wall surfaces and one of said other wall surfaces, and first interengaging means between one of said side edges of said body and said rail and second interengaging means between the other of said side edges of said body and said one of said other surfaces to support said body above said facility, said transverse edges being adjacent said first and second walls respectively said one of said other surfaces being said third vertical wall surface.

2. The subject matter of claim 1 in which said second interengaging means at said other side edge of said body includes an L-shaped strip on said third vertical wall surface, one flange of said strip being vertical and being secured to said third vertical wall surface, and the other flange being horizontal and said other side edge of said body resting on said other flange.

3. The subject matter of claim 1 in which said sheetlike body is translucent.

4. The subject matter of claim 1 in which said sheetlike body is upwardly arced transversely medially both longitudinally and transversely and in which said sheetlike body terminates in flanges on both sides and ends, and said sheet-like body is adjusted to dimensions between said first and second vertical wall surfaces and between said rail and said third vertical wall surface by flange trimming.

5. The subject matter of claim 1 in which said sheetlike body has a uniform transverse cross-section from end to end thereof and being fitted substantially to the distance between said first and second vertical wall surfaces by trimming.

6. The subject matter of claim 5 in which said sheetlike body is bendable and being upwardly arced and in which it is adjusted in width relative to the distance between said rail and said third vertical wall surface by bending and/or trimming.

7. The subject matter of claim 1 in which said sheetlike body is translucent and is formed of sawable fiberreinforced plastic material whereby the side edges of said body can be trimmed to fit the space between said rail and said third vertical wall surface.

8. The subject matter of claim 1 in which there is an electrical radiation source supported on the upper side of said body, and translucent means in the area of said body under said source, whereby said bathing facility will receive radiation from said source.

9. The subject matter of claim 8 in which said electrical radiation source is a light source.

10. The subject matter of claim 8 in which said electrical radiation source is an infrared heating source.

11. The subject matter of claim 8 in which said translucent means is a property of said sheet-like body which is formed of a translucent plastic.

12. The subject matter of claim 1 in which said side edges of sheet-like body lie substantially in the same horizontal plane and said body is domed between said edges, whereby said body is self-supporting between its edges.

13. The subject matter of claim 12 in which said side edges have horizontal flanges forming their margins, and said body being formed of sawable, fiberreinforced plastic whereby said body can be fitted to the space between said rail and said third vertical wall surface by flange trimming.

14. The subject matter of claim 13 in which said body has a reverse bend extending below the horizontal flange on the side of said body toward said rail. and said first interengaging means between said one side edge of said body and said rail is the adjacent flange which rests on top of said rail and said reverse bend which abuts the side of said rail, thereby securing said body against downward or outward movement of said one side edge

Claims

3. The subject matter of claim 1 in which said sheet-like body is translucent.

4. The subject matter of claim 1 in which said sheet-like body is upwardly arced transversely medially both longitudinally and transversely and in which said sheet-like body terminates in flanges on both sides and ends, and said sheet-like body is adjusted to dimensions between said first and second vertical wall surfaces and between said rail and said third vertical wall surface by flange trimming.

5. The subject matter of claim 1 in which said sheet-like body has a uniform transverse cross-section from end to end thereof and being fitted substantially to the distance between said first and second vertical wall surfaces by trimming.

6. The subject matter of claim 5 in which said sheet-like body is bendable and being upwardly arced and in which it is adjusted in width relative to the distance between said rail and said third vertical wall surface by bending and/or trimming.

7. The subject matter of claim 1 in which said sheet-like body is translucent and is formed of sawable fiber-reinforced plastic material whereby the side edges of said body can be trimmed to fit the space between said rail and said third vertical wall surface.

13. The subject matter of claim 12 in which said side edges have horizontal flanges forming their margins, and said body being formed of sawable, fiber-reinforced plastic whereby said body can be fitted to the space between said rail and said third vertical wall surface by flange trimming.

14. The subject matter of claim 13 in which said body has a reverse bend extending below the horizontal flange on the side of said body toward said rail, and said first interengaging means between said one side edge of said body and said rail is the adjacent flange which rests on top of said rail and said reverse bend which abuts the side of said rail, thereby securing said body against downward or outward movement of said one side edge of said body relative to said rail.

15. The subject matter of claim 14 in which said second interengaging means at said other side edge of said body includes an L-shaped strip on said third vertical wall surface, one flange of said strip being vertical and being secured to said third vertical wall surface, and the other flange being horizontal and the flange of said body on that side resting on said other flange of said L-sahped strip.