US3683579A

US3683579A - Artificial stone facing construction and method therefor

Info

Publication number: US3683579A
Application number: US67515A
Authority: US
Inventors: Jack M Beardsley
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-08-27
Filing date: 1970-08-27
Publication date: 1972-08-15
Anticipated expiration: 1989-08-15

Abstract

The disclosure comprises sheets of thin, porous, compressible backing material stapled to an underlying structure. The backing sheets butt up against each other to completely cover the surfaces which are to be covered by the artificial bricks. A coat of mortar-colored paint is applied to the outer surface of the backing sheets. While the coat of mortar-colored paint is still wet, imitation bricks are secured in rows to the backing sheet by nails with T-heads which are driven through the imitation bricks, through the backing sheet, and into the underlying structure. The nails are driven so that their heads are flush with the outer surface of the imitation bricks. The heads of the nails are covered with brick colored paint. The imitation bricks are spaced so that they cover the staples used to hold the backing sheet to the underlying structure. In this manner, the backing sheet is compressed beneath the imitation bricks and projects outwardly beyond the inner surfaces of the imitation bricks so that the junctions between the inner surfaces of the imitation bricks of the backing sheet are concealed, thus creating the appearance of real bricks set into real mortar.

Description

United States Patent Beardsley [s4] ARTIFICIAL STONE FACING CONSTRUCTION AND METHOD THEREFOR [72] Inventor: Jack M. Beardsley, 1961 Bellevue Drive, Glendale, Calif. 9120i [22] Filed: Aug. 27, 1970 [21] App]. No.: 67,515

521 user. ..52/3ll,52/385,52/389, 52/391,52/746 51 Int. Cl. ..E04f 13/14 [58] Field of Search ..52/309, 311, 314, 384-389, 52/390, 39], 746; 156/71 5] 3,683,579 [4 1 Aug. 15, 1972 Primary EQraminer-Alfred C. Perham Attorney-Reed C. Lawlor [57] ABSTRACT The disclosure comprises sheets of thin, porous, compressible backing material stapled to an underlying structure. The backing sheets butt up against each other to completely cover the surfaces which are to be covered by the artificial bricks. A coat of mortarcolored paint is applied to the outer surface of the backing sheets. While the coat of mortar-colored paint is still wet, imitation bricks are secured in rows to the backing sheet by nails with T-heads which are driven through the imitation bricks, through the backing sheet, and into the underlying structure. The nails are driven so that their heads are flush with the outer surface Of the imitation bricks. The heads of the nails are covered with brick colored paint. The imitation bricks are spaced so that they cover the staples used to hold the backing sheet to the underlying structure. In this manner, the backing sheet is compressed beneath the imitation bricks and projects outwardly beyond the inner surfaces of the imitation bricks so that the junctions between the inner surfaces of the imitation bricks of the backing sheet are concealed, thus creating the appearance of real bricks set into real mortar.

16 Claims, 3 Drawing Figures PATENTEDMIBIS m2 3,683,579

/@ /0 5' 2 /I6 k I JACK M. 56AED546V INVENTOR A Woe/V6 V ARTIFICIAL STONE FACING CONSTRUCTION AND METHOD THEREFOR BACKGROUND OF THE INVENTION This invention relates to an artificial stone construction for application to an underlying structure, and more specifically, to an artificial brick construction which consists of a backing sheet composed of compressible material secured to an underlying structure and imitation bricks secured to the backing sheet and underlying structure. Wen the backing sheet is compressed beneath the imitation bricks, it will project outwardly beyond the inner surface of the bricks and be visible in its uncompressed state in order to form a tight seal around the sides of the bricks, thus eliminating any cracks between the sides of the bricks and the backing sheet. This creates the impression of real bricks set into real mortar.

Artificial brick walls and the like are presently constructed of real or imitation bricks secured to a relatively in compressible surface. For example, one artificial brick wall employs a cement slab having intermittent indentations and projections in the slab which define sockets the size of the bricks. The bricks are secured in the indentations or sockets so that parts of the cement slab project between the bricks. This construction avoids the necessity for filling in mortar between the bricks. However, since the underlying cement slab is dry and relatively rigid when the bricks are placed in the indentations, cracks appear between the projections of the slab and the sides of the bricks. These cracks between the bricks and the slab betray the purpose of the bricks by detracting from the attempted impression of real bricks set into real mortar.

Another artificial brick construction presently in use consists of imitation bricks secured to a wall by a coat of mortar-colored mastic which is applied to the underlying structure and to the back of the bricks. The cracks between the bricks and the underlying mastic previously referred to do not appear in this construction. However, this mastic construction 'usually requires about a 6 hour wait for the mastic to set before imitation bricks can be applied. A sealer is usually required to be applied to the mastic surfaces. Also, the back of each individual brick must be coated with mastic. This all requires additional time and expense. The construction of my invention is much less expensive, can be completely installed in much less time than is the case of the mastic construction, and is easier and cleaner to install.

I have discovered that by employing a backing sheet of compressible material, such as a thin, porous sheet of polyurethane foam or the like, an artificial brick wall or the like may be constructed which in appearance more closely resembles real bricks set into real mortar than any of the artificial stone constructions heretofore employed.

In the best embodiment of this invention, a -inch thick polyurethane foam sheet is used as the backing sheet. In this type of construction, the polyurethane sheet is compressed beneath the imitation bricks to less than about one-half the thickness of the uncompressed backing sheet. When the backing sheet is thus compressed beneath an imitation brick, the backing sheet projects outwardly away from the underlying structure alongside the imitation brick so that the junction between the imitation brick and the backing sheet is substantially concealed from view. To aid in this illusion, a coat of mortar-colored paint is applied to the backing sheet. The imitation bricks are then secured to the backing sheet and to the underlying structure while the paint is still wet. This wet paint aids in concealing cracks between the bricks and the backing sheet, besides combining with the porous backing sheet to create the impression of mortar. A portion of the imitation bricks project beyond the backing sheet to give the appearance of real bricks embedded into mortar with what are known as combed or raked mortar joints between the bricks.

The bricks of this invention are composed of a binding or adhesive material, such as green tag casting plaster or the like, a lightening compound, such as per- I lite, expanded vermiculite or the like, and a coloring compound, such as red iron oxide or the like. Such imitation bricks are lightweight, fully color impregnated and porous enough to allow nails to be driven through them without cracking.

By employing this invention, a durable, lightweight, artificial stone construction can be installed in less time and more economically than the artificial stone constructions presently in use.

Any color of brick and mortar can be represented by employing appropriate coloring compounds and paints. Nails can be driven through the bricks, thus obviating the necessity of forming nail holes in the bricks as in other types of constructions. Because of its light weight, the artificial stone construction of this invention can be employed where ordinary bricks would be too heavy, such as on ceiling beams and the like. This construction can be employed both indoors and out doors and presents the appearance of real bricks embedded into real mortar, all without the use of either real bricks or mortar of any kind.

SUMMARY OF THE INVENTION This invention provides an artificial stone construction to be applied to an underlying structure comprising a compressible backing sheet which is held onto the underlying structure. Artificial stones are secured to the backing sheet so that the backing sheet is compressed beneath the artificial stones and projects substantially outward beyond the inner surfaces of the artificial stones around the sides of the stones and between adjacent stones thereby concealing the junction between the inner surfaces of the stones and the backing sheet and creating the appearance of real stones set into real mortar.

Many other features of this invention will become evident to those skilled in the art upon reading the following detailed description of the drawings wherein:

FIG. 1 is a perspective view of the artificial stone construction of this invention applied to an underlying structure;

FIG. 2 is a sectional elevational view of a portion of the construction taken along the line 2-2 of FIG. 1, and

FIG. 3 is a perspective view of one of the bricks employed in the best embodiment of this invention.

FIG. 1 shows the corner of a box form 10 such as an indoor planter or the like, which forms the underlying structure of the bestembodiment of this invention.

Typically, the underlying structure is made of plywood or the like. However, the underlying structure may be in any form and may be composed of any material which is capable of having a backing sheet secured to it by some means such as stapling, gluing, or the like, and which is capable of having nails or the like driven into it. Typical underlying structures are house walls, indoor house planters, ceiling beams, and the like.

FIGS. 1 and 2 show the artificial stone construction of this invention applied to the underlying structure 10. A backing sheet 14 composed of a spongy compressible material is secured to the underlying structure by staples 1,6 or the like. In the best embodiment of this invention, the backing sheet 14 is composed of polyurethane foam. The backing sheet may be composed of other substances or materials which have characteristics similar to those of polyurethane which will be described hereinafter.

One requirement for the backing sheet is that it be composed of a highly compressible spongy material. In the best embodiment of the invention, /z-inch thick sheets of porous polyurethane foam are employed which are capable of being compressed between the imitation bricks and the underlying structure, as will be explained hereafter, to such an extent that the backing sheet beneath the imitation bricks has a thickness of less than about one-sixteenth inch.

In the best embodiment of this invention, the backing sheet also has a rough surface which approximates the appearance of the rough surface of real mortar such as is usually visible between bricks. The backing sheet 14 is lightweight and easy to handle. Thus, it can be easily held onto the underlying structure 10 either by hand or by staples 16 while it is being painted and while the imitation bricks are being secured thereto, as will be explained hereafter.

In the best embodiment of this invention, staples 16 are employed to secure the backing sheet 14 to the underlying structure 10. The backing sheets 14 are secured to the underlying structure 10 so that their edges butt up against one another, thus forming a continuous covering over the entire surface of the underlying structure which is desired to be covered with the artificial stone construction. The backing sheet 14 is flexible enough to follow the contours of the underlying structure and may be secured around comers and the like.

A coat of mortar-colored paint 18 is applied to the outer surface of the backing sheet 14 while the backing sheet is held onto the underlying structure 10 by staples 16. This coat of paint 18 may consist of either textured or flat paint and may be varied in color according to the color of the mortar desired to be represented.

The rough texture of the backing sheet 14 combined with the coat of mortar-colored paint l8 creates the impression of real mortar applied to the underlying structure l0.

Imitation stones 20 may be formed to have the appearance of either man-made and natural occurring stones or construction materials, such as flagstone, cement blocks, granite and the like. In the best embodiment of the invention, the imitation stones 20 have the appearance of red clay bricks.

These imitation bricks 20 are composed of a mixture of one part adhesive or binder material, such as green Percent Retained Sieve Size Maximum Minimum 8 l0 0 I6 60 20 30 95 65 50 98 I00 I00 These materials are dry mixed and are then combined with one part of water while the water is being agitated. After the mixture has been agitated for about one minute, it is poured into brick molds and allowed to set.

The result is a red imitation brick which is lightweight and fully color impregnated throughout. This imitation brick 20 is solid and durable while at the same time being porous enough to allow nails to be driven through the brick 20 without cracking the bricks. Such an imitation brick 20 may be cut in any desired lengths or widths after it is formed in order to more easily adapt the brick to the particular construction desired.

The color, weight, hardness, and size of the bricks may be varied as desired. Typically, the imitation brick 20 is about 0.5 inches thick, about 8.125 inches long, and about 2.5 inches wide.

Imitation bricks 20 may also be composed of rubber, polyesters, concrete, or the like. Where a rubber, foam rubber, or other bendable material is utilized, the bricks are capable of being bent around comers for installation on curved surfaces. Where the bricks 20 are composed of concrete or other similarly hard material, it is common practice to perform nail holes in the bricks to allow nails to be driven through the bricks without danger of cracking the bricks.

While the cost of mortar-colored paint 18 is still wet, the bricks 20 are secured to the underlying structure 10 in rows 7% inch apart by nails 22 or the like. The bricks 20 are placed by hand in the positions desired and pressed firmly against the underlying structure 10 thereby compressing the backing sheet 14 while the nails 22 are being driven through the bricks 20, the backing sheet 14 and into the underlying structure 10. The nails 22 have T-heads and are 1 inch long T-shaped finishing nails. Nails 22 are driven into the bricks 20 so that their heads are completely embedded into the bricks 20 and are flush with the outer surface of the bricks.

When the bricks 20 are secured to the underlying structure 10 in this manner, the backing sheet 14 projects outwardly along the sides of the bricks. This outward projection or uncompressed portion of the backing sheet 14 between the bricks 20 serves to conceal the cracks which are normally seen between the inner surface of the bricks and the backing material used in other types of artificial stone construction. Furthermore, the coat of mortar-colored paint 18 serves to fill in any cracks between the side of the brick 20 and the backing sheet 14 which might otherwise exist since the coat of paint 18 is wet when the bricks 20 are pressed against and secured to the backing sheet 14.

In the best embodiment of the invention, the bricks 20 are secured over the staples 16 so that the staples 16 are concealed by the bricks 20. An alternative procedure for eliminating the staples 16 from view is to pull them out with pliers or the like after some bricks have been secured to each backing sheet. The bricks will retain the backing sheet in position on the underlying structure while the staples are removed.

After the bricks have been secured to the underlying structure 10 by nails 22 or the like, the heads of the nails 22 are covered with a coat of brick colored paint, thus concealing the manner in which the bricks are secured to the underlying structure.

FIG. 3 shows a corner brick 30 which is employed in this invention. This particular corner brick 30, also shown in FIG. 1, is constructed as one unit and employed in the same manner as has been described above for bricks 20. However, this brick 30 has three sides which illustrate all of the sides of imitation bricks which are employed in this invention.

Brick 30 has a top panel 32, an end panel 34, and a side panel 36. All three panels are molded integrally with one another. Any of these

panels

32, 34, 36 may be formed either by themselves or in an integral combination with an other panel to simulate various bricks 20. The brick 30 shown in FIG. 3 is employed to simulate a brick placed at the top corner of the wall shown in FIG. 1.

Top brick panel 32 would be used by itself, for example, to simulate bricks on the top of a wall which are not adjacent to a corner of the underlying structure. End brick panel 34 would be used by itself, for example, to simulate the end of a brick which is not adjacent to a corner of the underlying structure. Similarly, side brick panel 36 would be employed by itself, for example, to simulate the side of a brick which is not adjacent to one of the corners of the underlying structure. It is also possible to mold the

panels

32, 34 and 36 in various combinations to simulate other bricks 20. For example, a top-end brick would be composed of

panels

32 and 34 molded together as one unit, a top-side brick would be composed of

panels

32 and 36, an end-side brick would be composed of

panels

34 and 36, and the mirror image of brick 30 shown in FIG. 3 would be composed of

panels

32, 34 and 3 6.

It will be understood that other forms of artificial stones and other backing sheets composed of other materials may be employed which are similar to that disclosed above, all within the scope of this invention.

Although this invention has been described with reference to a particular embodiment and to particular applications, the principles involved are susceptible to numerous other applications, which will be apparent to those skilled in the art, and the scope of the invention is not to be limited by the proceeding embodiments.

The invention claimed is:

1. An artificial stone construction to be applied to an underlying structure, comprising:

a compressible backing sheet supported against the underlying structure; and

artificial stones secured in place by nail-like means extending from the interior of said artificial stones through said backing'sheet and into said underlying structure, said artificial stones being spaced apart to form free spaces between adjacent sides of said stones whereby the backing sheet is compressed beneath the artificial stones and relatively uncompressed portions of said backing sheet project substantially outward beyond the inner surfaces of the artificial stones around the sides of the stones and to a position short of the outer surfaces of said stones thereby concealing the junctions between the inner surfaces of said stones and said backing sheet from view and simulating a raked joint.

2. An artificial stone construction as defined in claim 1 wherein paint has been applied to the outer surface of said backing sheet thereby partially securing the artificial stones to said backing sheet and providing coloring to the uncompressed portions of said backing sheet.

3. An artificial stone construction as defined in claim 2 wherein said artificial stones are composed of a binding material, a lightening compound, and a coloring material.

4. An artificial stone construction as defined in claim 3 wherein said backing sheet is about one-eighth inch thick when uncompressed and about one-sixteenth inch thick when compressed and said artificial stone is about one-half inch thick.

5. An artificial stone construction as defined in claim 1 wherein said artificial stones are artificial bricks in which said binding material is green tag casting plaster, said lightening compound is expanded vermiculite and said coloring material is red iron oxide.

6. An artificial stone construction as defined in claim 1 wherein said compressible backing sheet is composed of sponge-like material.

7. In an artificial brick construction to be applied to an underlying structure having a backing sheet secured to the underlying structure, said backing sheet having the appearance of mortar, and a plurality of spaced apart imitation bricks secured to said backing sheet and to the underlying structure, the combination with the above designated parts wherein said backing sheet comprises a compressible material which is compressed beneath the imitation bricks and projects outward in relatively uncompressed condition beyond the inner surfaces of the imitation bricks and into the spaces between adjacent bricks whereby the junctions between the inner surfaces of the bricks and the backing sheet are concealed.

8. In an artificial brick construction to be applied to an underlying structure, comprising:

a compressible backing sheet having the appearance of mortar held onto the underlying structure;

a plurality of imitation bricks secured in rows to the outer surface of the backing sheet by T-shaped nails projecting through the bricks and into the underlying structure,

said backing sheet being compressed beneath the bricks and projecting outwardly beyond the inner surfaces of the bricks so that the junctions between the inner surfaces of the bricks and the backing sheet are concealed.

9. An artificial brick construction to be applied to an underlying structure, comprising:

a sheet of thin, porous, compressible backing material, stapled lightly to the underlying structure, said backing sheet having a rough textured surface facing outwardly;

a coat of mortar-colored paint applied to the outer surface of the backing sheet; and

a plurality of porous imitation bricks secured in rows to the outer surface of the backing sheet before the mortar-colored paint is dry by T-shaped nails projecting through the imitation bricks, through the backing sheet, and into the underlying structure so that the heads of the nails project into the outer surfaces of the bricks,

said imitation bricks being composed of a binding material, a lightening compound, and a coloring material,

said backing sheet being compressed beneath the bricks and projecting outwardly beyond the inner surfaces of the bricks around the sides of the bricks so that the junctions between the inner surfaces of the bricks and the backing sheet are concealed,

said artificial brick construction creating the appearance of real bricks set into real mortar.

10. An artificial brick construction as defined in claim 9 further comprising:

a coat of brick-colored paint applied to the head of each T-shaped nail, and

wherein said imitation bricks are secured to said' backing sheet in positions to conceal said staples,

said backing sheet being about inch thick when uncompressed and about 1/l6 inch thick when compressed and said imitation brick being about A inch thick.

11. An artificial brick construction as defined in claim 10 wherein said binding material is green tag casting plaster, said lightening compound is expanded vermiculite, and said coloring material is red iron oxide.

12. A method for applying an artificial brick construction to an underlying structure comprising the steps of:

stapling a sheet of compressible backing material to the underlying structure;

applying a coat of mortar-colored paint to the outer surface of the backing sheet;

nailing a plurality of porous imitation bricks to the outer surface of the backing sheet and to the underlying structure before said coat of mortarcolored paint is dry, the heads of said nails being driven into the outer surface of said imitation bricks, said backing sheet being compressed beneath the bricks and projecting outwardly beyond the inner 5 surfaces of the bricks around the sides of the bricks so that the junctions between the inner surfaces of the bricks on the backing sheet are concealed, said artificial brick construction creating the appearance of real bricks set into real mortar to the full depth of real bricks. 13. A method for applying an artificial brick construction to an underlying structure as defined in claim l 2 wherein said sta les are concealed b nailing the artrficral bricks over he staples, and fur er comprising the step of:

applying a coat of brick-colored paint to the heads of the nails.

14. A method for applying an artificial brick construction to an underlying structure as defined in claim 12 further comprising the step of:

removing any staples which are visible after the artificial bricks have. been nailed to the backing sheet.

15. A method for applying an artificial stone construction to an underlying structure comprising the steps of:

holding a sheet of compressible backing material on the underlying structure;

applying paint to the outer surface of the backing structure;

applying artificial stones to the backing sheet in spaced-apart relation to each other and in said application stage pressing the artificial stones against the backing sheet thereby compressing said backing sheet beneath said artificial stones while maintaining the portions of the backing sheet between the artificial stones in relatively uncompressed state so that those portions of the backing sheet extend substantially outwardly into the spaces between the artificial stones and beyond the inner surfaces of the artificial stones but short of the outer surfaces of the artificial stones whereby the junctions between the inner surfaces of the artificial stones and the backing sheet are concealed thereby simulating raked joints between the artificial stones.

16. The method of applying an artificial stone construction to an underlying structure as defined in claim 15 including the step of driving nails through the artificial stones and through the backing sheet and into the underlying structure.

Claims

1. An artificial stone construction to be applied to an underlying structure, comprising: a compressible backing sheet supported against the underlying structure; and artificial stones secured in place by nail-like means extending from the interior of said artificial stones through said backing sheet and into said underlying structure, said artificial stones being spaced apart to form free spaces between adjacent sides of said stones whereby the backing sheet is compressed beneath the artificial stones and relatively uncompressed portions of said backing sheet project substantially outward beyond the inner surfaces of the artificial stones around the sides of the stones and to a position short of the outer surfaces of said stones thereby concealing the junctions between the inner surfaces of said stones and said backing sheet from view and simulating a raked joint.

7. In an artificial brick construction to be applied to an underlying structure having a backing sheet secured to the underlying structure, said backing sheet having the appearance of mortar, and a plurality of spaced-apart imitation bricks secured to said backing sheet and to the underlying structure, the combination with the above designated parts wherein said backing sheet comprises a compressible material which is compressed beneath the imitation bricks and projects outward in relatively uncompressed condition beyond the inner surfaces of the imitation bricks and into the spaces between adjacent bricks whereby the junctions between the inner surfaces of the bricks and the backing sheet are concealed.

8. In an artificial brick construction to be applied to an underlying structure, comprising: a compressible backing sheet having the appearance of mortar held onto the underlying structure; a plurality of imitation bricks secured in rows to the outer surface of the backing sheet by T-shaped nails projecting through the bricks and into the underlying structure, said backing sheet being compressed beneath the bricks and projecting outwardly beyond the inner surfaces of the bricks so that the junctions between the inner surfaces of the bricks and the backing sheet are concealed.

9. An artificial brick construction to be applied to an underlying structure, comprising: a sheet of thin, porous, compressible backing material, stapled lightly to the underlying structure, said backing sheet having a rough textured surface facing outwardly; a coat of mortar-colored paint applied to the outer surface of the backing sheet; and a plurality of porous imitation bricks secured in rows to the outer surface of the backing sheet before the mortar-colored paint is dry by T-shaped nails projecting through the imitation bricks, through the backing sheet, and into the underlying structure so that the heads of the nails project into the outer surfaces of the bricks, said imitation bricks being composed of a binding material, a lightening compound, and a coloring material, said backing sheet being compressed beneath the bricks and projecting outwardly beyond the inner surfaces of the bricks around the sides of the bricks so that the junctions between the inner surfaces of the bricks and the backing sheet are concealed, said artificial brick construction creating the appearance of real bricks set into real mortar.

10. An artificial brick construction as defined in claim 9 further comprising: a coat of brick-colored paint applied to the head of each T-shaped nail, and wherein said imitation bricks are secured to said backing sheet in positions to conceal said staples, said backing sheet being about 1/8 inch thick when uncompressed and about 1/16 inch thick when compressed and said imitation brick being about 1/2 inch thick.

12. A method for applying an artificial brick construction to an underlying structure comprising the steps of: stapling a sheet of compressible backing material to the underlying structure; applying a coat of mortar-colored paint to the outer surface of the backing sheet; nailing a plurality of porous imitation bricks to the outer surface of the backing sheet and to the underlying structure before said coat of mortar-colored paint is dry, the heads of said nails being driven into the outer surface of said imitation bricks, said backing sheet being compressed beneath the bricks and projecting outwardly beyond the inner surfaces of the bricks around the sides of the bricks so that the junctions between the inner surfaces of the bricks on the backing sheet are concealed, said artificial brick construction creating the appearaNce of real bricks set into real mortar to the full depth of real bricks.

13. A method for applying an artificial brick construction to an underlying structure as defined in claim 12 wherein said staples are concealed by nailing the artificial bricks over the staples, and further comprising the step of: applying a coat of brick-colored paint to the heads of the nails.

14. A method for applying an artificial brick construction to an underlying structure as defined in claim 12 further comprising the step of: removing any staples which are visible after the artificial bricks have been nailed to the backing sheet.

15. A method for applying an artificial stone construction to an underlying structure comprising the steps of: holding a sheet of compressible backing material on the underlying structure; applying paint to the outer surface of the backing structure; applying artificial stones to the backing sheet in spaced-apart relation to each other and in said application stage pressing the artificial stones against the backing sheet thereby compressing said backing sheet beneath said artificial stones while maintaining the portions of the backing sheet between the artificial stones in relatively uncompressed state so that those portions of the backing sheet extend substantially outwardly into the spaces between the artificial stones and beyond the inner surfaces of the artificial stones but short of the outer surfaces of the artificial stones whereby the junctions between the inner surfaces of the artificial stones and the backing sheet are concealed thereby simulating raked joints between the artificial stones.