Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION
System for building formwork for concrete stairs and related methods
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0001] NA
FIELD OF THE INVENTION
[0002] The present invention relates to formwork for building concrete stairs.
More specifically, the
present invention is concerned with adjustable metal casings for creating
formworks for building
concrete stairs.
BACKGROUND OF THE INVENTION
[0003] 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
completed.
[0004] 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
[0005] 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.
[0006] More specifically, in accordance with the present invention, there is
provided a casing system
for building a formwork for building concrete stairs comprising: (a) at least
one side plate which can be
releasably secured to a supporting structure on a footing; the side plate
defining a side of at least one
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stair and defining the depth of a tread of said stair; (b) at least one riser
member for defining the rise of
the at least one stair; the riser member being complementary to the side
plate; and (c) means for
fastening the riser member to the side plate; wherein the side plate and riser
member are reusable.
[0007] In an embodiment, the side plate comprises holes enabling to releasably
secure the side plate
to the supporting structure. In a particular embodiment, the side plate is
releasably secured to the
supporting structure using screws or nails.
[0008] In another embodiment, the side plate is adaptable and can be used to
build stairs having
treads of varying depths, preferably of depths between 9 inches and 25 inches.
[0009] In a particular embodiment, the side plate defines the side of at least
two stairs, at least 3 stairs,
at least 4 stairs, at least 5 stairs or at least 6 stairs.
[0010] In a further embodiment the side plate is integrally formed i.e., made
in a single piece of
material.
[0011] In another embodiment, the side plate and the riser member further
define a nosing along the
tread of a stair, The nosing may be present along the entire periphery of the
tread or only on a portion
thereof (only the front of the tread).
[0012] The side plate may further comprises a support member for supporting a
riser member. In an
embodiment, the support member is integrally formed with the side plate. In
another embodiment, the
support member comprises an indentation to receive the riser member. In yet
another embodiment, the
support member is a comb having multiple teeth and indentations to receive the
riser member.
[0013] The above described system may advantageously comprise in accordance
with the present
invention one or more fastening means to fasten the riser member to the side
plate. In an embodiment,
the fastening means is a clamp for clamping the riser member to the side
plate. In a preferred
embodiment, the clamp is a c-shaped clamp and the side plate further comprises
a locking member to
lock the clamp on the side plate.
[0014] In an embodiment, the side plate and riser member are made of stainless
steel. In a particular
embodiment, the stainless steel is 1/4 inch thick.
[0015] In a further embodiment, the riser member is up to 12 feet long. In a
particular embodiment, the
riser member is 6, 8, 10 or 12 feet long.
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[0016] In another embodiment, the system further comprises at least one relay
plate for securing the
riser member to a wall and enabling the building of formwork for building a
flight of stairs along the wall.
[0017] In a related aspect, the present invention relates to a use of the
above-described system for
building a formwork for building concrete stairs.
[0018] 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
[0019] In the appended drawings:
[0020] 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);
[0021] Figure 2 is a perspective view of an embodiment of a system of the
present invention installed
on a two-sided structure (wood support fixed on a concrete footing);
[0022] Figure 3 shows a side view of the embodiment shown in Figure 2;
[0023] Figure 4 shows two embodiments (A and B) of side plates of the present
invention;
[0024] Figure 5A shows a plan view of an embodiment of a support member of the
present invention in
the form of a comb. Figure 5B is also a plan view of a further embodiment of a
support member of the
present invention having a single indentation, Figure 5C is a plan view of an
embodiment of a fastening
means of the present invention. Figure 50 is a plan view of an embodiment of a
relay plate of the
present invention;
[0025] Figure 6 shows a side view of an unfinished concrete stairway with side
plates installed on a
wood beam fixed on a concrete footing;
[0026] Figures 7 A and B show the metal casing system depicted in Figures 2
and 3, fully installed on
two wood beams fixed on each side of a concrete footing, prior to concrete
pouring to form the stairs;
[0027] Figure 8 shows the metal casing system depicted in Figures 2, 3 and 7,
fully installed on two
wood beams fixed on each side of a concrete footing following concrete pouring
showing fully formed
steps. A is a side view of concrete stairs built using the metal casing system
of the present invention
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with fully formed steps. B is an enlarged side view of the metal casing system
depicted in A with fully
formed steps;
[0028] Figure 9 shows staircases comprising concrete stairs built using the
metal casing system
depicted in Figures 2, 3 and 6 to 8. A. front view of a finished staircase
with concrete stairs built using
the metal casing system of the present invention. B. is a perspective view of
another staircase built
using the metal casing system of the present invention. C. is a side view of a
further staircase built using
the metal casing system of the present invention clearly showing the nosing on
each step;
[0029] Figure 10 shows a second embodiment of a side plate of a metal casing
system of the present
invention. The side plate shown in Figures 10 A, B and C differs from the
first embodiment of the
present invention in that the side plate enables to continue or carry the
nosing of a step on its side. This
embodiment is adjustable at a 450 degree angle. A is a perspective view of a
second embodiment of a
side plate of the present invention. B is a side view of the second embodiment
of a side plate of the
present invention. C. is a front view of the second embodiment of a side plate
of the present invention
shown in Figures 10 A and B; and
[0030] Figure 11 shows a side view of a third embodiment of a side plate of a
metal casing system of
the present invention. The side plate is integrally formed and used to build 4
concrete steps.
DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0031] The present invention is illustrated in further details by the
following non-limiting examples.
[0032] 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 stairs 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 step or tread (14) and a riser (16). The
tread is the part of the stairs that is
stepped on. The riser (16) extends upwardly or downwardly from an edge of a
tread (14) and connects a
tread to an adjacent tread. The riser (16) is thus the vertical portion
between each tread on a flight of
stairs. The tread (14) may optionally comprise a nosing (18) which is
positioned at the edge of the tread
opposite to the rise, along its width and (optionally along its depth) and
forms the part that protrudes
over the riser (16) beneath.
[0033] The overall height of a flight of stairs is called the overall rise
height (ORH) and the overall
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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.
[0034] A typical concrete flight of stairs is made using two stringers which
are the structural members
that support the risers. When building concrete stairs, a footing is first
typically built. The footing is
generally made of gravel (filling) and concrete (shell) but it can also be
made using other materials. A
wood frame may also be created such that no footing or base per se is build
and the flight of stairs is
cantilevered/hanging. The footing forms the base on which the concrete stairs
will be supported.
[0035] In conventional methods of building formwork for concrete stairs, two
stringers, usually made of
plywood are secured to the footing and used to form the formwork of a 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 (steps) are formed in concrete. Thus, a
typical formwork for
building concrete stairs does not comprise tread but only risers and
stringers. Typical formworks are
discarded once the concrete has been poured and has hardened. The building of
formworks for building
concrete stairs thus requires much time, effort and materials which are all
wasted once the project is
finished because the formworks are typically completely discarded when the
structure has been
finished.
[0036] Accordingly, the present invention provides a system for creating
formworks for building
concrete stairs which is easy to installed, requires much less time and
efforts compared to typical
formworks and is reusable. It uses up to 90% less wood and does not require
the use of bracings
(reinforcing structures) for stairs up to 12 feet wide.
[0037] Referring now to Figures 2 and 3, there is shown a first embodiment of
a metal casing system
of the present invention enabling the construction of a formwork for building
concrete stairs. The system
comprises side plates (22) which define the side of a stair or stairs. Once a
suitable footing or base has
been built, side plates are mounted on each side of the footing/base.
Preferably a supporting structure
or stringer (20) such as a wood beam or plywood sheet is first mounted (e.g.,
nailed) on each side of the
footing and the side plates are then screwed or nailed on the supporting
structure to avoid damaging
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the concrete covering the base or footing. The side plates (22) comprise a
series of holes (24) which
are used to fasten the plates to the supporting structure or stringer (20). In
the embodiments shown in
the figures, the holes are 3/8 inch wide but any suitable size is acceptable
as long as it allows the side
plate (22) to be secured to the supporting structure. In the first embodiment
shown in Figures 2, 3 and
4A and the embodiment shown in Figure 10, the holes (24) advantageously allow
the side plates (22) to
be adjusted to create a stair with a tread of desired depth. Thus, the side
plates (22) are used to define
the depth of the tread (14) or step on a given stair. In such an embodiment of
the present invention,
when a flight of stairs comprising several stairs or steps is built, side
plates can be independently
adjusted such that each tread has the same or a different depth.
[0038] In a particular embodiment, the side plates can be designed to
optionally enable the creation of
a nosing on an edge of a tread. As shown on Figures 2-4 and 11, the side
plates (22) comprise a
protrusion (26) on one edge which defines the shape of the nosing (18) on a
tread (14). Using the metal
casing system for building formworks for concrete stairs shown in Figures 2-8,
a nosing (18) is formed at
the edge of a tread opposite to a rise, along its width and forms the part
that protrudes over the riser
(16) beneath. This is best shown on Figures 9B and C, which show finished
concrete stair flights built
using the casing system of the present invention and in particular using the
side plates illustrated in
Figures 2-4.
[0039] In the embodiment shown in Figures 2, 3 and 4A, the side plate (22) is
made of 1/4 inch thick
steel. It is 27 inches long (including the protrusion (26) defining the nosing
(18)) and 7 3/8 or 8 inches
high. In the embodiment shown in Figure 4B, the side plate (22) is 12 inches
long (including protrusion
(26)) and 7 3/8 inches high. Similarly, the side plate is made of 1/4 inch
thick steel.
[0040] Optionally, the nosing (18) can be continued over the side of the
tread, along its depth. This is
possible using, for example side plates 22a such as that depicted in Figure
10. In this particular
embodiment, the upper portion of the side plate (22a) comprising the
protrusion (26) defining the design
of the nosing is positioned away from the lower portion comprising the holes
(24), allowing the plate to
be fastened on the supporting structure or stringer (20).The distance between
the lower portion (LP)
comprising holes (24) and the upper portion (UP) defines the depth of the side
nosing (26a). In a
preferred embodiment, the side plate 22a is 7 3/8 inches high. The lower
portion (LP) is 4 3/8 inches
high and the upper portion (UP) is 1 1/2 inches high. The middle portion (MD)
is positioned at a 45 angle
and is 1 1/2 inches high (see in particular Figures 10 B and C).
[0041] In another embodiment and turning now to Figure 11, the side plate (22)
of the present
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invention may be designed such that it can define the shape and support the
side of several stairs. For
example, it can be made in a single piece designed to accommodate 3, 4, 5, 6,
7 or 8 stairs. Multiple
units of such side plates (22) can also be used together to build a flight of
stairs of desired length. This
design is advantageously used for building multiple houses with repetitive
architecture, although it is not
adjustable. Another advantage of this design is that it is more rapidly
installed, The side plate (22) (and
riser members (30)) are installed as described for the embodiments shown in
Figures 2, 3 and 6-9.
[0042] Going back to Figures 2 and 3, the casing system of the present
invention further comprises a
riser member (30) to retain the concrete and to shape the riser (16) of a
stair (12). The riser member
(30) abuts to the outer edge of the side plate (22) such that it prevents
concrete from leaking. The riser
member (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 member (30) comprises an
indentation or curve
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). The riser member may be of any suitable
length and up to 12 feet
long. Preferably, the riser member is 6, 8, 10 or 12 feet long.
[0043] As shown in Figures 2 and 3, the riser member (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
located (28a, see Figure 5A) on the upper portion of the side plate (22). The
support member (28) can
be integrally formed with the side plate (22) or it can be a separate piece
welded or otherwise secured
to the side plate (22). In a preferred embodiment, the riser member (30) is
fitted between two teeth of
the comb (28a) to prevent the riser member (30) from moving under the weight
of concrete. The comb
(28a) shown in Figure 5A is 12 1/4 inches long and 1 'A inches high. It is
also made of % inch thick steel.
The presence of multiple channels between the teeth allows to position the
riser member (30) on the
side plate (22) below and thus, further allows to adjust the depth of a tread.
Typically, as in the case of
the comb 28a shown on Figure 5, each tooth corresponds to a depth of 1/2 inch.
Typical tread depths are
9" and 25" inches but depths in between these values as well as smaller or
larger depths are possible.
Alternatively, and as shown in Figures 3 and 5B, the support member can be in
the shape of a small
plate comprising a single indentation (28b) to fasten the riser member (30) to
the side plate (22). The
support member (28b) shown on Figure 58 is 1 1/2 inches X 1 1/2 inches and
made in 1/4 inch thick steel.
This support member is preferably used in the embodiment shown on Figure 11,
where the side plate
defines the side of several stairs In such a case, the depth of the tread of a
stair cannot be further
adjusted using the support member. This type of support member (28b) is
typically used to secure the
first riser to create the stair that is closest to the ground. Also, the upper
portion of the riser member (30)
may advantageously be further fastened to the side plate (22) by any
appropriate fastening means (32),
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In the particular embodiment shown in Figures 2, 3, 7 and 8, the fastening
means (32) is in the form of a
c-shaped clamp or hook (32a) which can be detachably attached to the side
plate (22) via a locking
member (32b) (best shown on Figure 8B). The c-shaped clamp is hammered in
place and joins the
outer edge of the rise and the locking member on the side plate (22) and helps
the rise to stay in place
under the weight of concrete. Preferably, the c-shape clamp and locking member
are made of 1/2 inch
thick steel. Of course, any other kind of clamp or fastening means may be used
in accordance with the
present invention.
[00441 In an embodiment, the system of the present invention can be used to
build concrete stairs
along a wall structure. Under such circumstances, a relay plate (34) can be
used to fasten the riser
member (30) to the wall. A relay plate (34) is affixed on at least one
extremity of the riser member (30).
As for the riser member (30), the relay plate (34) has a shape that is
complementary to the side plate
(22) to provide for the appropriate shape of nosing (18) or absence thereof.
[0045] From the foregoing description, it should be apparent that side plates
(22), riser member (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.
[0046] 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 plate (22), riser member (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 (18) can be of any shape and form. It can be present
or absent. If present, the
nosing (18) can be limited to the width of a tread as shown for example, in
Figures 1, 3, 8 and 9 or it can
be carried laterally on the side of the step along its depth. 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.
[0047] Furthermore, in accordance with the present invention, the side plates
(22), riser member (30),
relay plates (34), support member (28) and fastening means (32) may be of any
suitable material which
is durable and sufficiently strong. The various pieces in the above described
system can be of the same
material or may be of different materials. The side plates (22) and riser
members (30) must be in a
material which is sufficiently strong and resistant which does not bend under
the pressure of the
unhardened concrete. Fastening means (32), support members (28) and relay
plates (34) may be made
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of other less resistant reusable material since these pieces do directly bear
the load of unhardened
concrete. Exemplary particularly suitable materials include aluminum, tungsten
and steel. Preferably,
the side plates (22), riser member (30), support member (28), fastening means
(32) and relay plates
(34) are made of stainless steel. In a particular embodiment, the stainless
steel is 1/4 inch stainless steel.
[0048] The system of the present invention for building formwork to build
concrete stairs is typically
used in the following manner: 1) a typical stair footing is first build (e.g.,
concrete footing or gravel and
concrete footing); 2) preferably, a supporting structure or stringer (such as
a 2X4 wood beam or
plywood sheet) is then temporarily secured to the footing (in order to avoid
damaging the footing when
securing the side plates (22); 3) side plates (22) are then screwed or nailed
to the supporting structure.
If building a flight of stairs with two open sides; at least two sets of side
plate(s) (22) are installed; one
on each side of the stair flight (i.e., one facing the other); 4) one or more
riser members (30) are then
placed on each side plates and secured in place; 5) unhardened concrete or
other suitable material is
poured on the footing or base, between the side plates (22) and riser members
to form each step; and
6) once concrete has hardened, the side plates (22) and riser members (30) are
dismantled, and the
supporting structure (if any) is removed, thereby completing the building of a
concrete flight of stairs. A
sand finish is preferably applied on the base or footing, which will hide the
holes made in the concrete to
fix the supporting structure. All pieces (ex. side plates (22), riser members
(30); relay plates, etc.) are
reusable and can be used to build a different flight of stairs on another
building site.
[0049] 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.
