US3120083A - Carpet or floor tiles - Google Patents

Description

4, 1964 H. s. DAHLBERG ETAL 3,120,083

CARPET OR FLOOR TILES Filed April 4, 1960 4 Sheets-Sheet l TWP INVENTORS HFIROLD S. DFIHL BEFEC-i 74 i .E. Feeg gus B. QUINN flwvrm r- {M HTTOENEPS Feb. 4, 1964 H. s. DAHLBERG ETAL CARPET OR FLOOR TILES 4 Sheets-Sheet 2 Mill Filed April 4, 1960 INVENTORS HAROLD S. DQHLBERG FQEIfJNCIS B. QUINN HTTORNEVS H. S. DAHLBERG ETAL Feb. 4, 1964 CARPET OR FLOOR TILES Filed April 4, 1960 4 Sheets-Sheet 3 ENTORS BERG Ul N N W &\ O

I 5.=l.lE. HAROLD a DA 240 Fmwcls a. Q

@Mim, gy ATTORNEYS United States Patent 3,120,083 CET 0R FLOOR TILES Harold S. Dahlberg, Springfield, Mass, and Francis B.

Quinn, Hazardviile, Conn., assignors to Bigelow-Sanford, Inc., a corporation of Delaware Filed Apr. 4, 1960, Ser. No. 19,917 7 Claims. (Cl. 50413) The present invention relates to carpet or floor tiles and relates, more particularly, to carpet or floor tiles which may be installed in interlocking relationship with a series of adjoining tiles.

An object of the present invention is to provide carpet or floor tiles comprising several layers with one of said layers forming a base having configurations formed on the side edges thereof which will readily interlock with similar configurations on adjoining tiles in a self-aligning manner and thus, permit a series of such tiles to be installed by a unskilled person on a doit-yourself basis, without the use of adhesives or nails, to form a floor covering having a substantially continuous or uninterrupted surface.

Another object of the invention is to provide a carpet or floor tile which will be substantially free of raising at the edges thereof due to warping and which will readily conform to the contour of the surface on which it is laid.

A further object of the invention is to provide a carpet or floor tile which is economical to manufacture and in which the weight may be held to a minimum so as to avoid excessive transportation expense in the marketing and distribution of the manufactured tiles.

Another object of the present invention is to provide a carpet tile comprising several layers including a base having interlocking configurations formed along the side edges thereof which are self-aligning with corresponding configurations of adjoining tiles, but which are free from acute prominent saliencies or projections, especially at the corners of the tile, so as to minimize the possibility of accidental damage or injury to the interlocking configurations in shipment or handling of the tiles.

Other objects and advantages of the present invention will be apparent and better understood from the following description and the accompanying drawings, in which:

FIG. 1 is a fragmentary view in perspective of an installation of a series of carpet tiles embodying the invention;

FIG. 2 is a fragmentary plan view from the rear of an assembly of three carpet tiles embodying the invention;

FIG. 3 is a top plan View of a carpet tile embodying the invention;

FIG. 4- is a fragmentary view in section along line 4--4 of FIG. 3;

FIG. 5 is a fragmentary view in section similar to FIG. 4, but showing another form of the construction embodying the present invention;

FIG. 6 is a fragmentary view in section similar to FIG. 4, but showing still another form of tile construction embodying the present invention;

FIG. 7 is a bottom plan view of the carpet tile shown in FIG. 3, but on a smaller scale;

FIG. 8 is a section view of the base of the tile shown in FIG. 7 taken along line '88 of FIG. 7;

FIG. 9 is a bottom plan view of the carpet tile shown in FIG. 3, but on a smaller scale and illustrating another form of base;

FIG. 10 is a section view of the base of the tile shown in FIG. 9 taken along line 10-11i of FIG. 9.

FIG. 11 is a bottom plan view of the carpet tile shown in FIG. 3, but on a smaller scale and with parts broken away and showing still another form of base;

FIG. 12 is a section view of the base of the tile of FIG. 11 taken along line 1212 of FIG. 11;

FIG. 13 shows the bottom plan view illustrating an assembly of tiles embodying the invention having interlocking configurations arranged to permit the tiles to be placed in staggered relation relative to each other;

FIG. 14 is a fragmentary or perspective view of an installation of the tiles shown in FIG. 13;

FIG. 15 is a top plan View of a portion of a side edge of an installation of the carpet tiles shown in FIG. 3 with means for trimming the outer edge of said tiles and holding the outer tiles in place;

FIG. 16 is a section view taken along line 1616 of FIG. 15; and

FIG. 17 is a section view taken on line 17-17 of FIG. 15.

As shown in FIG. 1, a series of tiles 10 embodying the invent-ion may be installed, without the use of nails or adhesives, to form a floor covering in which the adjoining tiles abut and are interlocked with each other so as to present a continuous and uninterrupted surface. In such an installation, the individual tiles may be readily shifted to different positions or may be replaced as desired. As illustrated, the tiles may be of different colors and be arranged to form a checkered pattern. However, the surface design or coloring of the tiles form no part of the present invention and are illustrated here merely to show the adaptability of the basic structures of the tiles in different colors and textures to form different designs and patterns as desired.

Ti'les embodying the invention are polygonal in out line and preferably should have equilateral sides with corresponding interlocking elements on each side thereof so that any one side of a given tile may be fitted and interlocked with any other side of an adjoining tile or tiles. As illustrated, the tiles will generally be square in outline.

The tiles illustrated in FIG. 1 are provided with edge structures which interlock when a series of the tiles are laid in abutting relationship and in alignment, laterally or longitudinally, with respect to each other. The tiles illustrated in FIGS. 13 and 14 are provided with edge structures which are arranged to interlock when a series of the tiles are laid in abutting relationship with the tiles in alternate rows, in one direction, being offset or staggered with respect to the tiles in the adjoining rows.

Tiles made in accordance with the present invention comprise several layers, including an upper layer and a bottom layer with intermediate layers if desired. The upper layer may be a pile fabric such as is usually used for carpeting and the bottom layer or base has interlocking configurations in the form of undulations extending along its side edges which are shaped to engage with corresponding configurations extending along the side edges of adjoining tiles. If desired, intermediate layers in the form of cushioning or reinforcing material or both may be interposed between the base and the pile fabric. It will also be understood that other materials, such as plastic (vinyl), rubber or the like, may be substituted in place of the pile fabric.

Referring to FIGS. 1-4, there is a tile 10 comprising an upper layer of pile fabric 11 of the tufted type in which the pile elements are formed on a loosely woven material 12, such as burlap, lightweight duck or the like. The pile fabric 11 is attached to an inner layer 13 in the form of a cushion or pad made of jute, sponge or foam rubber, foam polyurethane, or other suitable material. The pile fabric may be attached to the inner layer by adhesives, needling or both and in some cases, such as foam rubber or a jute pad, the inner layer may be formed directly on the back of the pile fabric. The inner layer is in turn attached to a bottom layer or base 14 by an adhesive or other suitable manner. The base may be made of wood fibers, felted together, compressed into a board and preferably bonded, as for example, Masonite.

The upper layer of pile fabric has straight side edges and the outer side edges 15 of the inner layer or cushion 13 are coextensive and aligned with the outer side edges of the pile fabric. The base 14 has outer side edges 16 which extend along and undulate inwardly and outwardly of each of the side edges 15 of the inner layer to form similarly shaped projections 17 extending outwardly beyond the side edges 15 of the inner layer and alternating with similarly shaped recesses 18 extending inwardly from the side edges of the inner layer. The projections 17 and recesses 18 are complemental to each other so that the projections on one tile will be received snugly and conformably in the recesses of an abutting tile to form an intermating and interlocking connection therebetween. It will be noted that the straight side edges 15 of the inner layer are located at the mean position of the undulations forming the projections 1-7 and recesses 18 on the respective side edges of the base.

The projections 17 and recesses 18 are of arcuate shape and are dimensioned, in accordance with the present invention, so that when three tiles have been assembled about a given point, as shown in FIG. 2, a fourth tile may be fitted into place easily by sliding it into locking engagement with two angularly adjacent tiles. In order to permit this, the dimensions of the projections 17 and recesses 18 must be as follows: The ratio of the chordal length A (FIG. 2) of each projection 17 along the axis 20 (corresponding to the edge 15 of the inner layer 13), to the height 17 of the crest of each projection, i.e. the amplitude distance of greatest departure of each projection 17 and each recess 18 from said edge, must be greater than 5, i.e.

A r b Otherwise, the fourth tile cannot be slid into place without encountering interference from the projections on the adjoining tiles.

In the form of the tile shown in FIG. 3, which is a square tile adapted to be installed in alignment with adjoiningtiles in two rectangular directions (laterally or longitudinally), as shown in FIG. 1, three complete projections 17 and three complete recesses 18 are provided along each side edge of the base, and the edge locking configuration on all sides of the tile are of the same shape and are uniformly arranged so that all sides thereof are interchangeable and permit the tile to be installed in any desired'position with respect to adjoining tiles.

As a feature of the present invention, built-in gauge means are provided for assuring the edge registry of the base 14 with the inner layer or cushion 13 and in turn with the top layer of pile fabric 11 in manufacture of the tile. For this purpose, the base 14 is provided with corners 22 having rectangular converging edges 23 located at the mean position of the undulations and which are in registry with the edges 15 of the inner layer 13 and the edges of the top layer of pile fabric. The interlocking undulations forming the projections and recesses extend along the side edges of the base between the straight edges at the corners. Thus, assembly of the square outlined layer of pile fabric 11 and the square outlined inner layer or cushion 13 in accurate-registry with the base can be readily accomplished, as for example, in a jig through alignment of the various layers with the square corners 22 of the base. Such registry assures centering of the base in relation to the pile fabric and the cushion with the interlocking configurations 17, 18 on the side edges of the base 14 being properly aligned with respect to the side edges 15 of the cushion.

While the square corners 22 of the base do not form part of the interlocking configurations, they serve to locate such configurations, and since the region where accidental impact occurs most frequently during handling is at the corners, damage to the interlocking configurations during such handling is avoided or at least materially reduced.

The dimensions of the interlocking configurations along the edges of the base 14 may vary, but they should follow the restrictions of as explained above. Also, the amplitude of the projections 17 and recesses 18, i.e. the distance b (FIG. 2) from the edge line 15 of the inner sheet 13 or axis 20 to the crests of the waves defining these projections and re cesses preferably should be between A" and Az. A tile of about 18" square with these dimensions has been found to be convenient to make, store, handle and/or lay.

Specific examples of dimensions of the base 14, as applied to FIG. 2, with three full projections 17 and recesses 18 on each side as shown in FIG. 3 for a tile 18 inches square are as follows:

Corners Amplitude Chordel Rad. ll, (1, inches 11, inches length inches Alb A, inches Va A 2. S33 5. 250 11. 332 /1 ii 2. E33 2. am 5. use A 2. S33 2. 876 7. 550

would be 5.65, which is within the limits prescribed above.

A series of tiles, constructed as described above, can be easily installed or assembled by merely sliding the tiles into abutting relation to each other as they are laid on a floor or other surface to be covered. When the tiles are progressively laid edge to edge in abutting alignment with each other, the projections 17 on the base 14 of one tile extend beneath the inner layer 13 and into the recesses 18 of the base 14 of thenext tile. Thus, all adjoining tiles will be in mating interlocking relationship with each other.. The square corners 22 of the assembled tiles of each group of four tiles meet in the center of the group, and when three tiles of such a group have been assembled, the configuration of the interlocking elements permits the fourthto he slid easily into position to complete the group.

As another feature of the. invention, the tile 10 is constructed so that it is flexible enough to readily conform to any irregularities in the surface covered by the tile and will not rock. The flexibility of the tile also permits it to be placed into or removed a space equal to or slightly greater than the width of a tile as at the outer edge of an installation which is bounded by a wall or between parallel rows of tiles spaced by the width of one row of tiles, where sliding of a flat tile into position may not be easily accomplished. Under these conditions, flexibility of the tile will permit the tile to be bent upwardly at its middle so as to bring the opposite edges of the tile closer together, thereby facilitating. the removal or placement of the tile in the confined space.

It is also important where the base of the tile is made of a material suchas pressed bonded wood, as illustrated in FIG. 4, to prevent warping of the base which may occur because of changing conditions of humidity or the like and which may cause the outer edges of the tile to bend upwardly and thus, render the tile unsatisfactory for use as a floor covering. In addition, such a base will not readily conform to slight irregularities in the surface on which the tile is laid. The desired flexibility and the prevention of warping may both be achieved in a base of this character by scoring or cutting two series of parallcl intersecting V-shaped slots 24 in criss-crossed arrangement on the outer or bottom face of the base. These crossing slots 24 are preferably deep enough to permit the base 14 to flex about these slots without destroying or breaking through the remainder of the base. To be eflective for this purpose, the slots 24 may have a depth equal to about 75 to 80% of the thickness of the base 14 and the thickness of the base may be about thick.

FIG. shows a modified form of tile construction embodying the invention in which the pile fabric 11 is attached to an inner layer 130: in the form of a scrim sheet which is flexible and which is attached to a base 14a. The base 14a is similar in construction to the base 14 in FIG. 4, except that it has slots 24:: formed therein to render the base flexible which are of rectangular crosssection instead of being V-shaped as the slots shown in FIG. 4. The slots 24a may also have a depth equal to about 75-80% of the thickriess of the base 14a.

FIG. 6 shows a modified form of tile construction embodying the invention which comprises an upper layer of pile fabric 11, a composite intermediate layer comprising a scrim sheet 13a and a pad or cushion 13 of jute, foam rubber or the like and a base 14b of material which is inherently flexible but which has sufficient struc tural integrity so that the interlocking conformations 17 and 18 formed along its side edges corresponding to those on the base layer 14 in the construction of FIGS. 2, 3 and 4 will retain their conformation and serve effectively for tile interlocking purposes, as described above. A material which has been found to be satisfactory for this purpose is a latex saturated paper or cardboard, such as that manufactured by Texon, Inc., under the name of Texon and Arista. This form of material, which is customarily used for shoe inner soles is inexpensive to manufacture, is lightweight, can be made in thin sheets, and affords the desired amount of flexibility and stifiness for the purposes of the present invention. However, when a flexible material is used for the base, slots such as are employed in the construction shown in FIG. 4, are not required.

FIGS. 7 and 8 show one form of pattern which the slots 24a in the base 14a in the construction of FIG. 5 may assume. In this construction, the base 14a is formed of one piece of pressed wood and the slots 24a follow a grill or criss-crossed pattern with the number of panels defined by the slots being shown as constituting sixteen. The tile provided with a slotted base 24a, so constructed, can be flexed about the slots 24a in any selected panel region of the tile, thereby affording great maneuverability in the handling of the tile.

The pattern of slots 24a in the construction of FIG. 7 may also be applied to the base 14 of the tile shown in FIG. 4, which has the V-shaped slots 24 cut therein.

FIGS. 9 and 10 show a construction in which the base 14 of the tile shown in FIG. 4 has been sectionalized by two central gaps or cuts 25 extending at right angles to each other which divide the base into four equal square sections, each of which has slots 24 cut therein. Such an arrangement permits the tile to flex about these gaps 25 to a somewhat greater extent than is possible with the one-piece base as shown in FIGS. 7 and 8. While the slots 24 shown in FIGS. 9 and 10 are V-shaped as in FIG. 4, it will be understood that they may be rectangular in cross-section such as the slots 24a shown in FIG. 5.

FIGS. 11 and 12 show a form of tile in which the inner layer 13c and the base 140 are both formed of pressed wood or the like. In this case, the inner layer 130 is square in shape and the pile fabric may be attached to it either directly or through intervening layers of cushion or the like, in edge registry there with as described above. The base 14c has locking configurations in the form of alternate projections 17 and recesses 18 along its edges and also has square gauge corners 22, designed and arranged to be aligned with the edge of the layer 13c as described in connection with the layer 13 and base 14 of the tile shown in FIGS. 2, 3, and 4.

To impart the necessary flexibility to the layers 13c, 140, the base has slots 24c which extend through the full thickness thereof and partially into the inner layer 130, as shown in FIGS. 11 and 12. These slots may also be arranged in the form of a grill or criss-crossed pattern as in the tile shown in FIG. 7.

The square corners together with the configuration of the interlocking undulations of the tiles 10 of FIGS. 1 and 3 permit such tiles to be laid only in alignment with each other in two rectangular directions. FIGS. 13 and 14 illustrate tiles ltld having interlocking undulations and square corners which permit the tiles to be arranged, selectively, not only in alignment in two rectangular directions, as shown in FIG. 1, but also in a staggered relationship with respect to the tiles in adjoining rows of tiles. For this purpose, each side of the base 14d along which the undulating edges extend has two duplicate complete sets of alternate projections 17d and recesses 18d which are separated by a flat space or land 26 extending along the center axis of the undulation. The lands 26 are located at the center line of the base 14d on each side thereof in alignment with the edges 23d of the square gauge corners 22d of the base, and the length of the lands is twice the length of each of said corner edges.

In the specific form of the shown in FIGS. 13 and 14, for an 18 tile, each side of the base 14 is shown with one complete projection 17d and one complete recess 18d on each side of the land 26, and each corner edge 23d is A" long while the land 26 is /2" long. Except as noted, the dimensions of the interlocking configurations 17d, 18d, would be the same as described above in connection with FIGS. 2 and 3, with the same limitation requiring the ratio of A/ b to be greater than 5 to facilitate assembly in cases where the tiles are to be assembled in alignment in two rectangular directions.

For assembly in alignment in two rectangular directions, the tiles 10d of FIGS. 13 and 14 are laid as shown in FIGS. 1 and 2, and for assembly in staggered relationship, the tiles are laid in groups of three, two of which are in abutting interlocking alignment with the two corner edges 23d of the two aligned tiles in end to end alignment and the third tile is placed in abutting centered interlocking relationship with the two aligned tiles, the land 26 of this third tile abutting the aligned corner edges 23d of the two aligned tiles.

The tiles lild of FIGS. 13 and 14, except as noted, may be constructed as described in connection with FIGS. 1-12.

If the tiles shown in FIGS. 1-14 are to be assembled to form a floor covering for less than the full area of a room or the like, the projections of the interlocking edge configurations may be visible and be exposed along the outer sides of such an installation. These projections, although not obtrusive enough to be unsightly, might constitute catches on which one may trip and the outer tiles would perhaps have a tendency to move out of place. In order to cover such exposed edges and to hold the tiles in place, removable trimming means has been provided for installation, as shown in FIGS. 1517, along the outer edges of such an installation to cover and protect the projections. Such trimming means comprises a strip 36) in the form of a molding made of wood, metal or plastic by molding, extrusion or otherwise and which has a conformation adapted to mate and interlock with the edge interlocking conformations of the tiles on the outer edges of the installation. The molding strip 30 has an upper straight edge 31 on its inner side and on its lower inner side is formed with a strip-like tile interlocking section 3 2, which has its inner edge 33 centered with respect to the molding edge 31 and undulated to correspond to the undulations of the edge of the base 14 of the tile 10 to provide alternate projections 34 and recesses 35, corresponding in, size and shape to the alternate projections 17 and recesses 13 of the tiles and connecting lands 36 along the center of the undulations between groups of such alternate. projections 34 and recesses 35, each group corresponding to the. group of alternate projections 17 and recesses 18 on each side of the tile. With the inner edge 31 of the molding strip 30 abutting the straight edge of the inner sheet 13 of the tile, the projections 34 and recesses 35 on the strip mate interlockably with the projections 17 and recesses 18 on the tile. Since it is desirable to provide molding strips 30 longer than the length of a tile; i.e., to span a number of tiles, the land 36 on the strip is twice as long as the edges 23 of the corners 22 of the individual tiles so as to extend along the full length of and in conforming abutment with two of such corner edges of adjoining sides tiles where the molding strip 30 extends across the juncture of two tiles.

The tile interlocking part 32 of the strip 30 has been referred to as a strip-like section because this section in effect is like a fiat strip. Although this strip-like section is shown in the drawings as an integral part of the strip 30, it may very well be a separate strip fitted into a lower inner recess of the main body of the strip and secured thereto, as for example by screws, adhesive or the like.

Also, although the strip 30 shown is designed to fit the type of tile shown in FIGS. 1-4 and may be easily designed to fit the type of tile shown in FIGS. -12, it can be easily designed according to the principles illustrated in FIGS. -17 and previously described, to fit the type of tile shown in FIGS. 13 and 14. In that case, the interlocking section of the molding strip is designed with locking configurations corresponding to those on the tile 10d of FIGS. 13 and 14, with lands for abutting conformance with the intermediate lands 26 of the tiles and lands for abutting conformance with the corner edges 23 of adjoining tiles.

The molding strip 30 may, if desired, be held down to a surface or other flooring by easily removable nails 38. The molding strip 30 when applied, not only trims the sides of the rug and protects the interlocking configurations of the tiles or outer sides of the installation, but it also holds the assembled tiles against movement.

The carpet tiles of the present invention can be used in different colors or textures to produce different rug patterns or designs, can be easily stored and/ or shipped, can be easily laid, can be easily replaced when worn or stained and can be interchanged in a rug, for example, tiles may be interchanged between places where they have become worn and are in full view and places which are subjected to little traffic, which are not prominent and which consequently have tiles in better condition.

While the invention has been described with particular reference to various embodiments illustrated herein, it is to be understood that it is not to be limited thereto but is to be construed broadly and restricted solely by the scope of the appended claims.

We claim:

1. A floor carpet tile comprising a plurality of layers of generally quadrilateral shape, said layers being joined together to form a unit including a square upper layer comprising a carpet fabric presenting a walking surface and a base layer underlying said upper layer, said upper layer having straight side edges for abutting opposing side edges of adjoining tiles, said base layer having undulations extending along each of the side edges thereof for interlocking with corresponding undulations on an adjoining tile, said undulations forming curved projections and recesses of complementary shape, respectively extending alternately beyond and beneath the upper layer along the straight side. edges thereof with said straight edges centered with respect to the corresponding undulations, the ratio of the width of said projections and recesses as measured along said straight edges to the maximum amplitude thereof as measured from said straight edges being greater than five, the conformations of the edges of said base layer being similar on all sides, whereby any one side of the tile may be fitted and interlocked with any side of an adjoining similar tile in a floor covering installation.

2. A floor tile as defined in claim 1 wherein the undulations forming the projections and recesses along the side edges of the base layer periodically terminate in straight lines which are aligned with the straight side edges of the upper layer.

3. A floor tile as described in claim 1 wherein the undulations forming the projections and recesses along the edges of the base layer terminate in straight lines which are disposed at right angles to each other at the corners of the base layer and which are aligned with the straight side edges of the upper layer at the corners thereof.

4. A floor tile as described in claim 3 wherein the undulations along the edges of the base layer also terminate in straight lines at points intermediate the ends of said side edges, the last-mentioned straight lines being aligned with the straight edges of the upper layer and being twice as long as the straight lines at the corners of the base.

5. A floor tile as described in claim 1 wherein the base layer is formed of a flexible material.

6. A fioor tile comprising a plurality of layers of generally quadrilateral shape, said layers being joined together to form a unit including a square upper layer presenting a walking surface and a base layer underlying said upper layer, said upper layer having straight side edges for abutting opposing side edges of adjoining tiles, said base layer having undulations extending along each of the side edges thereof for interlocking with corresponding undulations on an adjoining tile, said undulations forming curved projections and recesses of complementary shape, respec' tively extending alternately beyond and beneath the upper layer along the straight side edges thereof with said straight edges centered with respect to the corresponding undulations, the ratio of the width of said projections and recesses as measured along said straight edges to the maximum amplitude thereof as measured from said straight edges being greater than five, the conformations of the edges of said base layer being similar on all sides, whereby any one side of the tile may be fitted and interlocked with any side of an adjoining similar tile in a floor covering installation.

7. A floor tile as described in claim 6, wherein the undulations forming the projections and recesses along the edges of the base layer terminate in straight lines which are disposed at right angles to each other at the corners of the base layer and which are aligned with the straight side edges of the upper layer at the corners thereof.

References Cited in the file of this patent UNITED STATES PATENTS Re. 16,867 Healy Feb. 7, 1928 Re. 17,020 Healy July 3, 1928 1,657,159 Greenebaum Jan. 24, 1928 1,796,973 Wright Mar. 17, 1931 1,808,591 Bruce June 2, 1931 2,175,698 Netz Oct. 10, 1939 2,293,751 May Aug. 25, 1942 2,758,044 Terry Aug. 7, 1956 3,001,902 Cooke et a1 Sept. 26, 1961 FOREIGN PATENTS 647,024 Great Britain Dec. 6, 1950 562,724 Canada Sept. 2, 1958

Claims (1)

1. A FLOOR CARPET TILE COMPRISING A PLURALITY OF LAYERS OF GENERALLY QUADRILATERAL SHAPE, SAID LAYERS BEING JOINED TOGETHER TO FORM A UNIT INCLUDING A SQUARE UPPER LAYER COMPRISING A CARPET FABRIC PRESENTING A WALKING SURFACE AND A BASE LAYER UNDERLYING SAID UPPER LAYER, SAID UPPER LAYER HAVING STRAIGHT SIDE EDGES FOR ABUTTING OPPOSING SIDE EDGES OF ADJOINING TILES, SAID BASE LAYER HAVING UNDULATIONS EXTENDING ALONG EACH OF THE SIDE EDGES THEREOF FOR INTERLOCKING WITH CORRESPONDING UNDULATIONS ON AN ADJOINING TILE, SAID UNDULATIONS FORMING CURVED PROJECTIONS AND RECESSES OF COMPLEMENTARY SHAPE, RESPECTIVELY EXTENDING ALTERNATELY BEYOND AND BENEATH THE UPPER LAYER ALONG THE STRAIGHT SIDE EDGES THEREOF WITH SAID STRAIGHT EDGES CENTERED WITH RESPECT TO THE CORRESPONDING UNDULATIONS, THE RATIO OF THE WIDTH OF SAID PROJECTIONS AND RECESSES AS MEASURED ALONG SAID STRAIGHT EDGES TO THE MAXIMUM AMPLITUDE THEREOF AS MEASURED FROM SAID STRAIGHT EDGES BEING GREATER THAN FIVE, THE CONFORMATIONS OF THE EDGES OF SAID BASE LAYER BEING SIMILAR ON ALL SIDES, WHEREBY ANY ONE SIDE OF THE TILE MAY BE FITTED AND INTERLOCKED WITH ANY SIDE OF AN ADJOINING SIMILAR TILE IN A FLOOR COVERING INSTALLATION.

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