JPH08105175A - Stair - Google Patents

Abstract

PURPOSE: To reduce the number of members by using a tread having the same member as that of a riser and to make it possible to adjust vertical length of the riser. CONSTITUTION: A stair is constituted of a tread 20 fixed on a step 10, a riser 30 erected in the rear of the tread 20 and a top rail 40 positioned before the tread 20 and, at the same time, the tread 20 and riser 30 are made of the same member. The top rail 40 is constituted of the upper surface section 41 continued to the tread 20, the front surface section 42 hung downward from that side of the upper surface section 41 and the lower surface section 43 folded in the direction of the rear from the lower end edge of the front surface section 42, and the upper end edge of the rise 30 is positioned in the rear side of the lower surface section 43.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a staircase, and more particularly to a staircase in which a footboard and a riser board are used in common to reduce the number of parts and the finish on site is made constant.

[0002]

2. Description of the Related Art Conventionally, various stairs have been provided in houses. Such a staircase is usually formed of a step board fixed on a step board and a riser standing upright in the back of the step board. And, here, the footboard is formed relatively thick in order to step up and down the stairs by stepping on its upper surface, but the riser board is sufficient if the back of the stairs cannot be seen. , Was formed of a relatively thin plate.

Therefore, a thick decorative board and a thin decorative board have been required. Further, if necessary, a front stile-equipped footboard in which a front stile is integrally fixed to the front part of the footboard is sometimes used. Further, normally, the stairs are formed so that the entire inclination angle is about 45 degrees. Such an angle is determined by the angle of the line connecting the tip edges of the treads. In order to determine this inclination angle, the length of the footboard in the front-rear direction or the length of the riser board in the up-down direction is a problem.

Therefore, conventionally, not only the stepping plate and the riser plate are formed as separate members including the thickness, but also
Further, in order to change the angle of inclination of the stairs or change the rise, it is necessary to provide a step board or a rise board having a size corresponding to the angle or the rise. In particular, when the footboard and riser of such various dimensions are prepared in positive dimensions, the number of members increases,
Not only was it difficult to manufacture, but the work of selective use on site was complicated. In particular, when using a front stilt tread as a tread, if this front stilt tread is to be prepared with a positive dimension, it is necessary to prepare a large number of relatively large members, which is inconvenient for manufacturing or storage. It was

On the contrary, in order to reduce the number of parts, it is necessary to form each part into a large size and to perform dimensional matching such as grinding on site, which not only increases the amount of work on site but also finishes. Had to rely on the skills of professional workers.

[0006]

Claim 1 of the present invention
The invention described is formed from a step board fixed on a step board, a riser standing upright in the back of the step board, and a front stile located in front of the step board, and the step board and the riser are the same member. The purpose of this is to reduce the number of members and to make the finish on-site uniform.

In addition to the object of the invention as set forth in claim 1, the invention as set forth in claim 2 further comprises: a front stile, an upper surface portion which is continuous with the tread, and a front surface portion which is vertically hung downward from the front side of the upper surface portion. And a lower surface bent from the lower edge of the front surface in the inward direction, and the upper edge of the riser is positioned on the inner side of the lower surface, thereby increasing the vertical length of the riser. The purpose is to adjust the thickness at the thickness of the lower surface.

Further, in addition to the object of the invention described in claim 1 or 2, the invention described in claim 3 is such that a plurality of front stiles having different depth dimensions of the upper surface are prepared so that they can be selectively used. The purpose is to change the inclination angle of the stairs connecting the front stiles only by changing the front stiles. In addition to the object of the invention described in claim 1, 2 or 3, the invention according to claim 4 corresponds to the surface of the step plate, the riser plate and the front stile when the core material and the stairs are formed. The purpose of the present invention is to facilitate the production of the step board, the riser board, and the front stile by forming the decorative board attached to the surface.

The invention according to claim 5 is the invention as defined in claims 1, 2, and 3.
In addition to the object of the invention described in 4 or 4, in addition to forming the footboard and the riser board in a parallelogram section that can be connected as a clasp, the footboard and the riser board can be connected to the front side of the front stile with no space on the front side of the footboard. By providing a 45 degree cut,
The purpose of this is to facilitate the connection by connecting the tread plate and the riser plate by fastening.

According to a sixth aspect of the present invention, in addition to the object of the fifth aspect of the invention, the footboard and riser plate are formed of a core material and a decorative plate adhered to both surfaces of the core material. By doing so, it is intended that the surfaces of both the step board and the riser plate become the decorative boards when they are connected by the fastening. The invention according to claim 7 is the invention according to claim 2,
In addition to the object of the invention described in 3, 4, 5 or 6, a standing portion is provided upward from the back side of the lower surface portion, and the upper edge of the riser plate is located at the back side of the lower surface portion and the standing portion. By letting
The purpose of the present invention is to increase the margin of the length adjustment by allowing the vertical length of the riser plate to be adjusted not only in the thickness portion of the lower surface portion but also in the standing portion.

The invention according to claim 8 is the invention according to claim 2, 3,
In addition to the object of the invention described in 4, 5, 6 or 7, a riser plate is provided between the front surface portion and the lower surface portion such that the taper portion that becomes lower in the depth direction is provided. The purpose of this is to prevent the tip of the foot from impacting the tip of the tread when it is lifted up.

The invention as defined in claim 9 is claim 1,
In addition to the object of the invention described in 2, 3, 5, 7 or 8, a tread plate, a riser plate and a front stile are provided on the surface of the fine powder of the cellulosic material, and the fine powder has a smaller diameter and is harder than the fine powder. The purpose of the present invention is to form a wood grain pattern by coloring and molding a resin mixed with a powder formed by carrying the above, and to make it look as if it was made of a solid material.

[0013]

In order to achieve the above-mentioned object, the invention according to claim 1 of the present invention is a step plate fixed on a step plate and a riser standing upright in the back of the step plate. It is characterized in that it is formed from a board and a front stile located in front of the step board, and that the step board and the riser board are members having the same outer shape.

According to a second aspect of the present invention, in addition to the configuration of the first aspect of the invention, the front stile has an upper surface portion which is continuous with the footboard and a front surface portion which extends downward from the front side of the upper surface portion. And a lower surface portion formed by bending the lower end edge of the front surface portion in a depth direction, and an upper end edge portion of the riser plate is positioned on the inner side of the lower surface portion. In addition to the configuration of the invention according to claim 1 or 2, the invention according to claim 3 prepares a plurality of front stiles having different top surface depth dimensions,
It is characterized in that it can be selectively used.

Further, the invention according to claim 4 is the invention according to claims 1 and 2.
Alternatively, in addition to the configuration of the invention described in 3, the tread plate, the riser plate, and the front stile are formed from a core material and a decorative plate attached to a surface corresponding to the surface when the stairs are formed. And According to a fifth aspect of the present invention, in addition to the configuration of the first, second, third or fourth aspect of the present invention, the step plate and the riser plate are formed in a parallelogrammatic cross section that can be connected as a clasp, and the front stile It is characterized in that a 45-degree cut portion that can be connected to the front side of the footboard without a gap is provided on the back side of the.

Further, in addition to the constitution of the invention according to claim 5, the invention according to claim 6 is characterized in that a step plate and a riser plate are formed from a core material and a decorative plate adhered to both surfaces of the core material. It is characterized by having done. In addition to the configuration of the invention according to claim 2, 3, 4, 5 or 6, the invention according to claim 7 is provided with a standing portion upward from the back side of the lower surface portion, and the upper edge portion of the riser plate. Is located on the inner side of the lower surface portion and the standing portion.

The invention according to claim 8 is the invention according to claim 2,
In addition to the constitution of the invention described in 3, 4, 5, 6 or 7, a taper portion is provided between the front surface portion and the lower surface portion so that the depth direction becomes lower. The invention according to claim 9 is characterized in that, in addition to the constitution of the invention according to claim 1, 2, 3, 5, 7 or 8, a tread plate and a riser plate and a front stile are provided on the surface of a fine powder of a cellulosic material. In addition, a resin mixed with powder formed by supporting a fine powder having a smaller diameter and a hardness smaller than that of the fine powder is formed by coloring to form a wood grain pattern.

[0018]

According to the first aspect of the present invention, since the step plate and the riser plate have the same outer shape, not only the number of members can be reduced, but also the finish on the spot can be made constant. Furthermore, because the front stile is located in front of the footboard,
It is a staircase with a good appearance.

According to the invention as set forth in claim 2, such a staircase allows the vertical length of the riser plate to be adjusted in the vertical direction by locating the upper edge of the riser plate at the inner side of the lower face portion. Can be done in the thickness part of. Furthermore, in the invention according to the third aspect, it is possible to change the inclination angle of the entire stairs by using the front stile with different depth dimensions on the upper surface.

In the invention according to claim 4, the whole can be manufactured at low cost by using the plywood as the core material. In the invention according to claim 5, since the step plate and the riser plate can be connected so as to be fastened, the connection is easy and the positioning can be performed at the same time. Further, in the invention according to claim 6, both surfaces of the tread plate and the riser plate become decorative plates when they are connected by a fastener.

In the invention according to claim 7, the vertical length of the riser plate can be adjusted not only in the thickness portion of the lower surface portion but also in the standing portion, so that the margin for length adjustment is increased. Is. Further, in the invention according to claim 8, since the taper portion whose depth is lowered is provided between the front surface portion and the lower surface portion, when the stairs are climbed, the foot inserted near the riser plate is lifted. At times, the tip of the foot is prevented from impacting the tip of the tread.

In the invention according to claim 9, the tread plate, the riser plate, and the front stile are formed by carrying fine powder having a diameter smaller than that of the fine powder on the surface of the fine powder of the cellulosic material. Since the resin mixed with the powder was colored and molded so as to have a wood grain pattern, the wood grain appears on the member that can be seen from the outside, and it looks as if it was made of solid wood.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a main part of a staircase according to the present invention, and FIG. 2 is an enlarged sectional view of a main part showing a front stile different from the staircase shown in FIG. In FIG. 1, the stairs are formed by a step board 20 fixed on the step board 10, a riser board 30 standing upright in the back of the step board 20, and a front stile 40 located in front of the step board 20.

Here, the step plate 10 is a rectangular plate that is used upright, and the length in the vertical direction becomes short at the portion where the front stile 40, which is the front side of the stairs, is located. As described above, the front-stage portion 11 is formed in which the square notch is omitted. Further, in this illustrated example, a force bundle 60 is provided in the depth direction of the step plate 10. The footboard 20 has the same outer shape as the riser board 30, has a predetermined area, and has an inclined surface 50 so that the cross section which can be connected using the footboard 20 and the riser board 30 as a stop is a parallelogram. Has been formed.

Therefore, the footboard 20 and the riser board 30
Are connected to each other so that the inclined surfaces 50 of the footboard 20 are retained at the inner part of the footboard 20. Further, when the step board 20 and the riser board 30 are combined in this way, the inclined surface 50 at the upper end portion of the riser board 30 is inclined such that the front side is located at the uppermost portion, and the inclined surface 50 at the front side of the step board 20. Has an inclination such that the upper edge projects to the front.

Further, the front stile 40 has an upper surface portion 41 which is continuous with the footboard 20, a front surface portion 42 which extends downward from a front side of the upper surface portion 41, and a lower end edge of the front surface portion 42 which is bent in a depth direction. The lower surface portion 43, the upright portion 44 standing upright from the back side of the lower surface portion 43, and the back portion 45 further bent in the back direction from the upper edge of the upright portion 44. The upper surface portion 41, the front surface portion 42, and the back portion 45 are formed so as to sandwich the front step portion 11 of the step plate 10 from the front. Further, on the back side of the upper surface portion 41, a 45-degree cut portion 46 having a most protruding lower end edge is formed in order to enable connection with the front side of the footboard 20 without a gap.

Further, the upper end portion of the riser plate 30 is provided with the step plate 10.
It is located between the back side of the front stage portion 11 and the standing portion 44 of the front stile 40. Next, the assembly of such stairs will be described. First of all, the step plate 10 is fixed to a not-shown blank or the like. Next, the footboard 20 is fixed to the stepboard 10 from the bottom of the stairs. For this fixing, the tip of the inclined surface 50 on the far side of the step plate 10 is attached to the step plate 20.
It is performed so that it may be located in the deepest part of the upper surface.

Next, the lowermost riser plate 30 is fixedly positioned below the lowermost step plate 10. Furthermore, this riser 3
After fixing 0, or simultaneously with fixing the riser plate 30, the front stile 40 is fixed in front of the footboard 20. In this way, the bottom step plate 20, the riser plate 30 and the front stile 4
Fixed to 0.

Then, the footboard 20 is fixed to the next step board 10. This fixing is performed so that the distal end portion of the inclined surface 50 of the step plate 10 on the far side is located at the deepest portion on the upper surface of the step board 20. Then, the inclined surface 50 of the riser plate 30 provided between the upper step and the inclined surface 50 on the inner side of the lower step plate 20 is fixed so as to be fastened.

Further, after fixing the riser plate 30 or simultaneously with fixing the riser plate 30, the front stile 40 is fixed in front of the upper step plate 20. In this way, the stairs 10, the riser plate 30, and the front stile 40 are sequentially fixed to complete the stairs. In such a case,
The step plate 20, the riser plate 30, or the front stile 40 can be fixed by nails or the like, or by adhesion or the like.

If the length of the lower surface of the step plate 20 and the upper surface 41 of the front stile 40 is formed to be slightly longer than the length of the step plate 10 in the front-rear direction, the step plate 10 will be slightly larger than the designed value. Even if it is made long, there is no gap between the footboard 20 and the front stile 40. Conversely, the footboard 2
When fixed so that no gap is formed between 0 and the front stile 40, a gap may be formed between the front edge of the step plate 10 and the back surface of the front portion 42 of the front stile 40. At this time, since this gap is not visible from the outside, it is not a problem, and when it is fixed by adhesion, it also functions as an adhesive pool.

In the present invention, the step board 20 and the riser board 30 are provided.
Since and are members having the same outer shape, they can be formed by the same processing. In addition, if the materials are the same, the number of members can be reduced. Furthermore, since the front stile 40 is located in front of the footboard 20, the stairs have a good appearance. Furthermore, as in the example,
If the step plate 20 and the riser plate 30 are formed in a parallelogram in cross section so that they can be connected so as to be fastened,
Connection is easy and mutual positioning can be performed at the same time.

Of course, the tread plate 20 and the riser plate 30 may be simple rectangular plates. At this time,
For example, the lower end of the riser plate 30 is placed and connected to the deepest part of the step plate 20 to connect them. Note that, here, the footboard 20 and the riser board 3
It is also possible to form both 0 as a single plate. However, the footboard 20 and the riser board 30 may be formed of a core material and a decorative board attached to the surface corresponding to the surface when the stairs are formed. By doing so, the footboard 20 and the riser board 30 can be formed at low cost.

In such a case, if the step plate 20 and the riser plate 30 are simply rectangular plates, it suffices to attach the decorative plate only to one side of the core material. However, if the step plate 20 and the riser plate 30 are formed into a parallelogram in cross section as in the illustrated example, the surfaces of the step plate 20 and the riser plate 30 when the stairs are formed are different. Therefore, in this case, it is necessary to attach the decorative plates to both surfaces of the core material.

Further, in this embodiment, the front stile 40 is provided with an upper surface portion 41 which is continuous with the footboard 20, a front surface portion 42 which extends downward from the front side of the upper surface portion 41, and a lower edge of the front surface portion 42. The lower surface portion 43 and the lower surface portion 4 which are bent in the depth direction
3 is formed from an upright portion 44 standing upright from the back side of 3, and an upside portion 45 bent further in the back direction from the upper end edge of the upright portion 44. When formed in this way, the upper surface portion 4
Since the front step portion 11 of the step plate 10 can be sandwiched from the front by the front surface portion 42, the front portion 42, and the back portion 45, the front stile 40 can be easily fixed to the step plate 10.

Further, with this structure, when the lower riser plate 30 is positioned and fixed to the lower portion of the upper stage plate 10, the upper end of the lower riser plate 30 is located above the front stage portion 11 of the stage plate 10. Since it is located between the back side and the standing portion 44 of the front stile 40, if it is between the lower surface of the rear portion 45 of the front stile 40 and the lower end of the standing portion 44 of the front stile 40, the lower surface of the inner portion 45 is temporarily assumed. Even if there is a gap between and, it will not be visible from the outside. Therefore, by appropriately setting the distance between the lower surface of the back portion 45 of the front stile 40 and the lower end of the standing portion 44 of the front stile 40, it is possible to provide a margin for fixing the riser plate 30.

Furthermore, the step plate 1 is the distance between the lower surface of the inner portion 45 of the front stile 40 and the lower end of the standing portion 44 of the front stile 40.
By changing the pitch in the height direction of 0, it is also possible to slightly change the inclination angle of the entire stairs. That is, as compared with the case where the upper edge of the riser plate 30 is in contact with the lower surface of the back portion 45 of the front stile 40, there is a gap between the upper edge of the riser plate 30 and the lower surface of the inner portion 45 of the front stile 40. If it occurs, the stairs will be steep.

However, the inclination angle of the entire stairs can be changed by setting the front stile 40 to the upper surface, that is, the upper surface portion 41 in the illustrated example.
It is possible to prepare steep stiles 40 having different depth dimensions and use the front stile 40 having a large dimension to make the inclination angle gentle, and to use the front stile 40 having a small dimension to make the inclination angle steep. That is, in this embodiment, even when the step board 20 and the riser board 30 have the same shape, the inclination angle of the entire stairs can be selected by selectively using the plurality of front stiles 40. It is a thing.

The front stile 40 is replaced by, for example, the footboard 20.
Even if it is formed from an upper surface portion 41 continuous with the front surface portion 41, a front surface portion 42 that extends downward from the front side of the upper surface portion 41, and a lower surface portion 43 that is bent from the lower edge of the front surface portion 42 in the depth direction. In the range of the thickness of the lower surface portion 43, it is possible to provide a margin for fixing the riser plate 30 or adjust the inclination angle of the stairs.

Of course, the front stile 40 is folded in the depth direction from the upper surface portion 41 continuous to the tread plate 20, the front surface portion 42 extending downward from the front side of the upper surface portion 41, and the lower end edge of the front surface portion 42. It is formed by a curved lower surface portion 43 and a standing portion 44 which is erected upward from the back side of the lower surface portion 43, and a back portion 45 is formed.
Similarly, even when the riser is not provided, a margin for fixing the riser plate 30 can be provided or the inclination angle of the stairs can be adjusted within the height range of the standing portion 44.

Next, the embodiment shown in FIG. 2 will be described. In this embodiment, a taper portion 47 is formed between the front surface portion 42 and the lower surface portion 43 of the front stile 40 so that the depth direction becomes lower.
Is provided. When formed in this way, it is possible to prevent the tip of the foot from impacting the tip of the step board 20 when the foot inserted up to the vicinity of the riser board 30 is lifted when climbing the stairs. Of course, here, the taper portion 47 may be formed to be curved instead of being linear as in the illustrated example.

Further, the step plate 20, the riser plate 30 and the front stile 40 described above are formed by supporting fine powder of cellulosic material on the surface of which fine powder having a smaller diameter and harder than the fine powder is carried. When the resin mixed with is formed to have a wood grain pattern by color forming, the entire stairs are made of resin, but it looks as if they were made of wood.

Further, when manufactured in this manner, the footboard 2
0 and the riser plate 30 have no front and back sides, and even when both are manufactured in a parallelogram for connecting the both to the fastening, both the front and back sides can be located on the surface of the stairs. Further, here, the footboard 20, the riser board 30, and the front stile 40 can be extrusion-molded, and the woodgrain pattern can be more clearly produced by the extrusion molding. Here, the "cellulosic material" refers to wood powder or the like. The "fine powder having a smaller diameter and harder than the fine powder" means fine metal powder such as titanium oxide, ferrite, aluminum, nickel and silver, or fine non-metal powder such as ceramic.

[0044]

As described above, according to the first aspect of the present invention, the step plate fixed on the step plate,
By forming the riser standing upright in the back of the footboard and the front stile located in front of the footboard, and by using the same material for the footboard and the riser, the number of members can be reduced and the finish on site can be achieved. Can be stabilized.

In addition to the effect of the invention described in claim 1, the invention according to claim 2 is characterized in that the front stile is provided with an upper surface portion which is continuous with the tread, and a front surface portion which extends downward from the front side of the upper surface portion. And a lower surface bent from the lower edge of the front surface in the inward direction, and the upper edge of the riser is positioned on the inner side of the lower surface, thereby increasing the vertical length of the riser. The thickness adjustment can be performed in the thickness portion of the lower surface.

Further, in addition to the effect of the invention described in claim 1 or 2, the invention described in claim 3 is characterized in that a plurality of front stiles having different upper surface depth dimensions are prepared so that they can be selectively used. By changing the front stile, it is possible to change the inclination angle of the stairs connecting the tips of the front stile. In addition to the effect of the invention according to claim 1, 2 or 3, the invention according to claim 4 further comprises a step board, a riser board, and a front stile.
By forming the core material and the decorative board attached to the surface corresponding to the surface when the stairs are formed, the step board, the riser board, and the front stile are easily manufactured.

The invention according to claim 5 is the invention as defined in claims 1, 2, and 3.
In addition to the effect of the invention described in 4 or 4, in addition to forming the footboard and riser plate in a parallelogrammatic cross-section that can be connected as a clasp, it can be connected to the front side of the front stile with no space on the front side of the footboard. By providing a 45 degree cut,
The tread plate and the riser plate are connected by fastening to facilitate the connection.

According to a sixth aspect of the present invention, in addition to the effect of the fifth aspect, the step plate and the riser plate are formed of a core material and a decorative plate adhered to both surfaces of the core material. As a result, both surfaces of the tread plate and the riser plate become the decorative plates when they are connected by the fastening. The invention according to claim 7 is the invention according to claim 2, 3, 4, 5 or 6.
In addition to the effects of the invention described in (1), the upright portion is provided above the back side of the lower surface portion, and the upper end edge of the riser plate is positioned on the back side of the lower surface portion and the upright portion, whereby the riser plate is provided. The length adjustment in the vertical direction can be performed not only in the thickness portion of the lower surface portion but also in the standing portion, so that the length adjustment margin is increased.

The invention according to claim 8 is the invention according to claim 2,
In addition to the effect of the invention described in 4, 5, 6 or 7, the riser plate is provided when the stairs are climbed by providing a taper portion having a lower depth direction between the front surface portion and the lower surface portion. This prevents the tip of the foot from impacting the tip of the tread when it is lifted up.
The invention according to claim 9 relates to claim 1, 2, 3, 5,
In addition to the object of the invention described in 7 or 8, a tread plate, a riser plate, and a front stile are formed by carrying fine powder having a smaller diameter and harder than the fine powder on the surface of the fine powder of the cellulosic material. It is intended to form a wood grain pattern by coloring and molding a resin mixed with powder so that the entire stairs are made to look like a solid material.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts of a staircase according to the present invention.

FIG. 2 is an enlarged cross-sectional view of an essential part showing a front stile different from the staircase shown in FIG.

[Explanation of symbols]

10 step board 11 front step section 20 step board 30 riser board 40 front stile 41 upper surface section 42 front surface section 43 lower surface section 44 standing section 45 deep section 46 cut section 47 taper section 50 inclined surface 60 force bundle

Claims (9)

[Claims] 1. A tread plate fixed on a step plate, a riser plate standing upright in the back of the tread plate, and a front stile located in front of the tread plate, and the tread plate and the riser plate having the same outer shape. Stairs characterized by being a member of. 2. A front stile, an upper surface portion continuous with the footboard, a front surface portion extending downward from the front side of the upper surface portion, and a lower surface portion bent in a depth direction from a lower edge of the front surface portion. The stairs according to claim 1, wherein the stairs are formed from the upper end edge portion of the riser plate and the upper end edge portion of the riser plate is located on the inner side of the lower surface portion. 3. The stairs according to claim 1 or 2, wherein a plurality of front stiles having different depth dimensions on the upper surface are prepared so that they can be selectively used. 4. The step board, the riser board, and the front stile are formed of a core material and a decorative board attached to a surface corresponding to the surface when the stairs are formed. Stairs described in 2 or 3. 5. The step plate and the riser plate are formed in a parallelogram cross section that can be connected as a clasp, and a 45-degree cut portion that can be connected to the front side of the front plate without a gap is provided on the back side of the front stile. The stairs according to claim 1, 2, 3 or 4, characterized in that. 6. The stairs according to claim 5, wherein the step plate and the riser plate are formed of a core material and a decorative plate attached to both surfaces of the core material. 7. A standing portion is provided upward from the back side of the lower surface,
7. The stairs according to claim 2, 3, 4, 5 or 6, wherein the upper edge of the riser plate is located on the back side of the lower surface and the upright portion. 8. The stairs according to claim 2, wherein a taper portion having a lower depth is provided between the front surface portion and the lower surface portion. 9. A resin in which a tread plate, a riser plate and a front stile are mixed with a powder formed by supporting a fine powder having a diameter smaller than the fine powder and a hard powder on the surface of the fine powder of the cellulosic material. A colored pattern is formed so as to exhibit a wood grain pattern.
Stairs described in 7 or 8.