CA2801091A1 - System for building formwork for concrete stairs and related methods - Google Patents

Abstract

The present invention provides a system for use in formwork for building concrete stairs which is durable and reusable, which can be rapidly mounted and dismantled on site and which is adjustable to a variety of flight of stairs having different widths, rises and pitches. The system comprises (a) at least one side plate which can be fastened to a stringer; to form the side of a tread, the side plate defining the depth of the tread; (b) a riser plate for defining the rise of a stair; and (c) means for fastening the riser plate to the side plate; wherein the side plate and riser plate are reusable and wherein the side plate can be adjusted to build treads of varying depths.

Description

TITLE OF THE INVENTION
System for building formwork for concrete stairs and related methods CROSS REFERENCE TO RELATED APPLICATIONS
[0001] NA
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] NA
FIELD OF THE INVENTION

[0003] The present invention relates to formwork for building concrete stairs.
More specifically, the present invention is concerned with an adjustable system for creating formworks for building concrete stairs.
BACKGROUND OF THE INVENTION

[0004] In typical concrete stairway systems, it has been common practice to construct formwork, comprised of various elements at a building site to receive concrete and form the stair structure. The function of the formwork is primarily directed to the retention and control of the concrete when the structure is being erected. The formwork is typically made of wood and discarded once the concrete has been poured and has hardened. Because wood often bends under the load of concrete, wood formworks often need to be reinforced, especially in larger structures. Thus, the building of formwork for building concrete stairs requires much time, effort and materials which are all wasted once the project is finished because the formwork is typically completely discarded when the structure has been finished.

[0005] The present description refers to a number of documents, the content of which is herein incorporated by reference in their entirety.
SUMMARY OF THE INVENTION

[0006] An object of the present invention is thus to provide a system which is durable and reusable, which can be rapidly mounted and dismantled on site and which is adjustable to a variety of flight of stairs having different widths, rises and pitches.

More specifically, in accordance with the present invention, there is provided a system for building a formwork for a flight of stairs comprising: (a) at least one side plate which can be fastened to a stringer;
to form the side of a tread, the side plate defining the depth of the tread;
(b) a riser plate for defining the rise of a stair; and (c) means for fastening the riser plate to the side plate; wherein the side plate and riser plate are reusable and wherein the side plate can be adjusted to build treads of varying depths.

[0007] Other objects, advantages and features of the present invention will become more apparent upon reading of the following non-restrictive description of specific embodiments thereof, given by way of example only with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In the appended drawings:

[0009] Figure 1 is a side view of a typical flight of stairs showing measurements of rise height (RH), overall rise height (ORH), tread depth (TD), run length (RL), going (G) and pitch line (P);

[0010] Figure 2 is a perspective view of an embodiment of a system of the present invention installed on 2 side structures (stringers);

[0011] Figure 3 shows a side view of the embodiment shown in Figure 2;

[0012] Figure 4 shows two embodiments (A and B) of side plates of the present invention;

[0013] Figure 5 A and B show a plan view of two embodiments of a support system of the present invention, Figure 5C is a plan view of a fastening means of the present invention. Figure 5D is a plan view of a relay plate of the present invention.
DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0014] The present invention is illustrated in further details by the following non-limiting examples.

[0015] The system of the present invention can advantageously be used to build a formwork for flight of stairs of various sizes and shapes. A typical flight of stairs (10) is shown in figure 1. The flight of stairs (10) consists of a number of stairs (12) and usually a landing or platform at the top and/or bottom. An intermediate platform may also be built as part of the stair between the bottom and the top levels and is typically used to allow the stairs to change direction or to allow the user to rest. Each individual set of stairs (12) consists of a tread (14) and a riser (16). The tread is the part of the stairs that is stepped on.

The riser (16) extends upwardly from an edge of a tread (14) and connects a tread to an adjacent tread.
The riser (16) is the vertical portion between each tread on the stairs. The tread (14) may optionally comprise a nosing (18) which lies at the edge of the tread opposite to the rise, along its width and forms the part that protrudes over the riser (16) beneath.

[0016] The overall height of a flight of stairs is called the rise height (RH) and the overall length of the stairs is the run length (RL). The rise height (RH) of each step is measured from the top of one tread to the next. The ratio of rise height to run length is the pitch (P). The width (W) of a tread is measured from one side to the other and the tread depth (TD) is measured from the outer edge of the nosing (18) to the riser (16) on the opposite edge. The going of a step (G) is the horizontal distance from the edge of the nosing of a step to the edge of the nosing of the adjacent step. The number of stairs (12) in a flight of stairs is deduced by the number of risers present. In the example shown in Figure 1 there are 4 risers and therefore it is a 4-step flight of stairs.

[0017] A typical concrete flight of stairs is made using two stringers which are the structural members that support the risers, When building concrete stairs, two stringers, typically made of plywood are used to form the formwork of the flight of stairs. Risers are then supported and attached onto the two stringers on each side to enable the building of steps and retain the concrete when pouring. The treads are form in concrete. Thus a typical formwork for building concrete stairs does not comprise tread but only risers and stringers, Referring now to Figures 2 and 3, there is shown one embodiment of a system of the present invention in a formwork for building concrete stairs. The system comprises side plates (22) which define the side of a stair, The side plates (22) comprise a series of holes (24) which are used to fasten the plates to the supporting structure or stringer (20). The holes (24) advantageously allow the side plates (22) to be adjusted to create a stair of desired depth. Thus, the side plates (22) define the depth of the tread (14) on a given stair. In a particular embodiment, the side plates can be designed to enable the creation of a nosing on an edge of a tread. As shown on Figures 2-4, the side plates (22) comprise a protrusion (26) on one edge which defines the shape of the nosing (18) on a tread (14).
[0018] The system further comprises a riser plate (30) to retain the concrete and to shape the riser (16) of a stair (12). The riser plate (30) abuts to the side plate (22) such that it prevents concrete from leaking. The riser plate (30) is thus, complementary (i.e., it mates) to the design of the side plate (22).
For example, in the embodiment shown on Figures 2 and 3, the riser plate (30) comprises an indentation that is complementary to the protrusion (26) on the side plate (22) to enable the creation of a nosing (18) along the edge of a tread (14).

[0019] As shown in Figures 2 and 3, the riser plate (30) is supported by the side plate (22) located below by a support member (28). In an embodiment, the support member is in the shape of a comb (28a, see Figure 5A) affixed to the side plate (22). The riser plate (30) is fitted between two teeth of the comb (28a) to prevent the riser plate (30) from moving under the weight of concrete. The presence of multiple ridges between the teeth allows to support the riser plate (30) independently of the depth of the tread, and thus, of the position of the side plate (22) below. Thus, the support member also allows adjusting the depth of the thread. Typically, as in the case of the comb 28a shown on Figure 5, each teeth corresponds to a depth of 1/2 inch. Typical thread depth are 9" and 25"
inches but smaller or larger depths are possible. Alternatively, and as shown in Figures 3 and 5B, the support member (28) can be in the shape of a small plate comprising a single indentation (28b) to fasten the riser plate (30) to the side plate (22). Also, the upper portion of the riser plate (30) is fastened to the side plate (22) by any appropriate fastening means (32) such as a hook [0020] In an embodiment, the system of the present invention can be used to build concrete stairs along a wall structure. Under such circumstance, a relay plate (34) can be used to fasten the riser plate (30) to the wall. A relay plate (34) is affixed on at least one extremity of the riser plate (30). As for the riser plate (30), the relay plate (34) has a shape that is complementary to the side plate (22) to provide the appropriate shape of nosing (18).

[0021] From the foregoing description, it should be apparent that the stringers (20), side plates (22), riser plate (30) support member (28), fastening means (32) and relay plate (34) form a structure which, when erected at the building site, constitutes a formwork which receives a settable material in a fluent state such as unhardened concrete to create a flight of stairs. Upon setting of the concrete, the system is dismantled and ready to be used on the next job site.

[0022] Furthermore, one skilled in the field of building concrete stairs will appreciate that the system of the present invention can be modified to accommodate different rise height, tread width and nosing shapes and sizes. For example, side plates (22), riser plate (30) and relay plate (34) can be made into various sizes and shapes based on the desired measures of the stair structure and of the desired look of the stairs. The nosing can be of any shape and form. It serves mainly an esthetic function and may be present or not on all or some of the stairs. A combination of different nosing may also be used.

[0023] Furthermore, In accordance with the present invention, the side plates may be of any suitable material sufficiently strong and resistant which does not bend under the pressure of the unhardened concrete. Exemplary suitable material include aluminum, tungsten and steel.
Preferably, the side plates are made of stainless steel. In a particular embodiment, the plates are made of 1/4 inch stainless steel.

[0024] Although the present invention has been described hereinabove by way of specific embodiments thereof, it can be modified, without departing from the spirit and nature of the subject invention as defined in the appended claims.

Claims (2)

1. A system for building a flight of stairs comprising:
a) At least one side plate which can be fastened to a stringer; to form the side of a tread, said side plate defining the depth of the tread;
b) A riser plate for defining the rise of a stair; and c) Means for fastening the riser plate to the side plate;
wherein said adjustable side plate and riser plate are reusable and wherein said side plate can be adjusted to build treads of depths.

2. The system of claim 1, further comprising at least one relay plate.