Note: Descriptions are shown in the official language in which they were submitted.
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TITLE: FLOORING SHEET AND MODULAR FLOORING SYSTEM
FIELD OF THE INVENTION
The present invention relates to flooring and in particular to wet area
flooring.
The invention has been developed primarily for providing wet area sheet
flooring and
will be described hereinafter with reference to this application. However, it
will be
appreciated that the invention is not limited to this particular field of use.
BACKGROUND OF THE INVENTION
The following discussion of the prior art is intended to place the invention
in an
appropriate technical context and enable the advantages of it to be more fully
understood. However, any discussion of prior art throughout the specification
should
not be considered as an express or implied admission that such art is widely
known or
forms part of common general knowledge in the field.
One known method of laying a foundation for wet area flooring involves
abutting sheets of compressed fibre cement side by side across a desired wet
area and
subsequently fastening the sheets in place. A disadvantage of compressed fibre
cement products currently used for this application is that they are
particularly heavy,
making transportation, handling and installation difficult. Furthermore, the
density of
the compressed products prevents effective pneumatic or power nail fastening
and in
order to screw the sheets in place, the screw holes must be pre-drilled and
countersunk
which is time-consuming relative to pneumatic or power nailing.
The abutting edges of the sheets are typically fastened to joists wherever
possible to minimise relative movement between adjacent sheets. Current
practice is
also to provide support on trimmers between floor joists to the edges that are
not
supported continuously on a floor joist, in order to provide adequate support
for the
edges and reduce the likelihood of relative movement between the abutting
edges of
adjacent sheets.
Once the floor sheeting is secured and adequately waterproofed, tiles can be
laid in conventional manner. In many instances, floor sheeting is installed
directly
over subflooring. The subflooring may comprise particle-board, press board,
OMD, or
other such timber-based subflooring products. If the waterproofing is not
installed
correctly, if it deteriorates over time, or if defects in the waterproofing
surface and
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connections develop, water may penetrate through to the underlying floor
sheeting which,
depending on the sheet flooring material, may become damaged due to water
effects such as
swelling and other mechanisms. This in turn can disrupt the finish of the
flooring surface or the
integrity of the underlying structure.
In addition to the desirability of avoiding problems related to moisture
absorption after
installation, it is also highly desirable for a product to resist moisture
absorption during
transport and storage. For example, although compressed fibre cement is
generally resistant to
moisture damage, moisture absorption can lead to increased mass during storage
prior to
installation, thereby increasing transportation costs and making handling more
burdensome. A
means of resisting moisture absorption during storage prior to installation is
therefore desirable
for ease of handling, installation and transportation.
It is an object of the present invention to overcome or ameliorate one or more
of the
disadvantages of the prior art, or at least to provide a useful alternative.
DISCLOSURE OF THE INVENTION
Accordingly, in an aspect, there is provided a fibre reinforced cement bound
flooring
sheet that is suitable for use in domestic wet area flooring, is lower in
density than conventional
compressed fibre cement wet area flooring, and is nailable, wherein said
flooring sheet has a
bending strength sufficient to withstand a uniformly distributed load of at
least 5 kPa when
supported at 450mm centres along its length, and wherein said sheet includes
connecting means
at opposed edges, such that the sheet may be interlockingly engaged with an
adjacent
complementary sheet to form a coplanar support surface, wherein said
connecting means
include tongue and groove formations disposed respectively on opposite
longitudinal edges of
each flooring sheet, whereby the tongue on one sheet and the groove on the
adjacent sheet
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cooperate to provide secure interlocking engagement between adjoining sheets
and wherein a
longitudinal cavity is formed between the interlocking tongues and grooves, to
permit insertion
of a sealant or a glue between the adjoining sheets.
Preferably, the sheet flooring material is nailable with conventional
pneumatic or power
nailing equipment.
Preferably, the sheets are strong enough to meet loading requirements for
domestic
construction flooring on supporting members spaced at 450 mm centres. In one
preferred
embodiment, the fibre reinforced cement sheet has a dry density lower than
about 1.25 g/cm3. It
is preferable that a fibre reinforced cement bound sheet having a nominal
thickness of 19mm
exhibits a bending strength sufficient to withstand a uniform load of 5 to 9
kPa when supported
at 450 mm centres along its length, whether the cement bound sheet is dry or
saturated with
water.
Typically, the sheets have a front or outer surface, a back surface, and a
thickness
therebetween. In addition, the sheets have edges of substantially uniform
depth corresponding
to the thickness between the front and back surfaces. In one preferred form,
the described
sheets have at least one surface sealed with a polymeric surface coating to
give at least one
surface of the sheet resistance to moisture
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absorption. Typically, the outer surface of the sheet is sealed with the
polymeric
coating. However, additional or alternative surfaces may be coated as well,
and the
entire sheet is coated in some preferred embodiments. The polymeric coating is
preferably specifically formulated to achieve and maintain a strong bond to
tile
adhesives and bedding materials. On the bottom surface of the sheet the
surface
coating is preferably adapted to bond to typical adhesives used to bond sheet
flooring.
On the edges of the sheet the surface coating is preferably adapted to bond to
sealants
or glues used in the connection of such sheets.
In another preferred form, the sheet is reinforced with a substantially
continuous layer of reinforcing material such as sheets or fibres of metals,
inorganic
fibres, polymeric fibres, carbon fibres or a combination or the above. The
reinforcing
material can be added in a plane of the sheet in any position throughout the
sheet
thickness and is preferably positioned at or towards at least one of the outer
surfaces.
The reinforcing material may be uni-directional or multi-directional, spaced,
matt or
woven. The reinforcing material is preferably embedded into the sheet material
during
green forming of the sheet, pressed into the surface of the green sheet
article in a green
state, or bonded to the surface in a cured or green state. Where glass fibre
reinforcement is used, the fibre is preferably resistant to alkali attack.
Alkali resistant
glass or polymer coated glass fibre are examples of suitable materials.
Another aspect of the invention provides a modular flooring system for a wet
area, said flooring system including at least one flooring sheet as previously
defined,
and complementary connecting means permitting said flooring sheet to be
interlockingly engaged with an adjacent sheet to form a substantially coplanar
support
surface.
In one preferred form, the adjacent complementary sheet is also formed from
fibre cement, more preferably a density modified fibre cement sheet having a
dry
density lower than about 1.25g/cm3. In another preferred form, the adjacent
complementary sheet is formed from particle board.
Preferably, the fibre cement sheet is generally rectangular and the connecting
means run along a longitudinal edge. More preferably, the connecting means run
along both longitudinal edges. In one preferred form, the connecting means
take the
form of tongue and groove formations respectively defined on opposite
longitudinal
edges of the sheet. In this embodiment, the tongue on one sheet and the
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complementary groove on the adjacent sheet are preferably formed to cooperate
with one
another to allow a secure connection between the sheets. Various types of
tongue and groove
geometries are contemplated, including a lock system wherein the tongue is
configured with a
slight protrusion along its length and the groove is further configured with a
corresponding
recess along its length to accept the protrusion.
Preferably, the tongue and groove are configured such that when a tongue and
groove
on adjoining sheets are interlocked, a cavity is created between the tongue
and the groove along
their lengths to allow glue to be inserted. The glue in this case preferably
acts either to bond the
connection and/or seal the connection to moisture as required for
waterproofing wet areas such
as bathroom floors.
In another preferred form, the connecting means take the form of grooves
formed in
opposite longitudinal edges of each sheet and a complementary elongate joining
member
adapted for simultaneous engagement with the respective adjacent grooves of
adjoining sheets.
Preferably, embodiments of the fibre cement sheet disclosed herein have a dry
density
of less than about 1.5 g/cm3. More preferably, the fibre cement sheet has a
dry density of less
than about 1.25 g/cm3.
Preferred embodiments of the fibre cement sheet include elements such as
microspheres,
pearlite and volcanic ash.
In a particularly preferred form, embodiments of the fibre cement sheet
composition
include those disclosed in United States Patent No. 6,572,697, entitled "Fiber
Cement Building
Materials with Low Density Additives". In addition, the preferred fibre cement
sheets may be
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formulated according to embodiments disclosed in United States Patent No.
6,346,146 entitled
"Building Products" and also according to embodiments disclosed in Australian
Patent No.
AU 515151, entitled "Fibre Reinforced Cementitious Articles".
In some preferred embodiments, the average thickness of the fibre cement
sheets is
preferably between about 10 mm and 30 mm, and more preferably between
16 to 22 mm. However, in certain embodiments, the thickness may be greater
than or
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less than the disclosed thicknesses yet still provide the advantageous
characteristics
contemplated by the disclosed embodiments.
According to a further aspect of the invention, there is provided a method of
installing a modular flooring system as defined above, including the steps of
aligning
two or more of the flooring sheets on a support platform and engaging the
connecting
means on the adjoining sheets so as to form a coplanar support surface.
Preferably, the sheets are fastened to a support surface platform formed by
framing members disposed in spaced apart relationship. Various materials may
be
used to form the support surface platform such as timber, steel or concrete.
The sheets are preferably nailed to the support surface platform. However,
other fastening techniques such as screwing or gluing may also be used to
secure the
sheets in place.
The connecting means on opposed edges are preferably formed by machining.
However, this may also be achieved by other methods such as casting,
extruding, or
fastening.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention will now be described, by way of
example only, with reference to the accompanying drawings in which:
Figure 1 is a perspective view of a first embodiment of a modular flooring
sheet according to the invention, shown with tongue and groove connecting
means;
Figure 2 is a side view of a series of interconnected modular flooring sheets
of
the type shown in Figure 1;
Figure 3 is a perspective view of an alternative embodiment of a modular
flooring sheet according to the invention, shown with connecting means in the
form of
grooves and joining member;
Figure 4 is a side view of a series of interconnected modular flooring sheets
of
the type shown in Figure 3;
Figure 5 is a plan view of a uniform distributed load testing apparatus and a
sample of flooring sheets installed in the testing apparatus; and
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Figure 6 is a front view of a portion of the testing apparatus of Figure 5
showing the spaced apart support members supporting the flooring sheet sample.
PREFERRED EMBODIMENT OF THE INVENTION
Referring to the drawings, the invention provides a modular flooring system
including at least one generally rectangular fibre cement sheet 1 having
connecting
means 2 on longitudinal opposed edges such that the sheet 1 may be
interlockingly
engaged with an adjacent complementary sheet to form a coplanar support
surface 3,
as seen in Figures 2 and 4. The adjacent complementary sheet may be formed
from
any material having complementary connecting means, such as a further fibre
cement
sheet or a sheet of particle board.
The connecting means 2 serves to resist relative movement, and in particular
co-planar misalignment, between abutting sheets along the joins. It will be
appreciated
by those skilled in the art that the connecting means may take many different
forms.
In Figures 1 and 2, the connecting means take the form of tongue and groove
formations 4 and 5 respectively defined on opposite longitudinal edges of the
sheets.
Preferably, when a tongue and groove of adjoining sheets are interlocked, a
cavity 6 is
created to allow for glue to be inserted.
In another preferred form, as shown in Figures 3 and 4, the connecting means
take the form of grooves 7 formed in opposite longitudinal edges of each sheet
and a
complementary elongate joining member 8 adapted for simultaneous engagement
with
the respective grooves of adjoining sheets, as shown in Figure 4.
While the embodiments shown in the accompanying figures illustrate
connecting means having square or rectangular geometries, it will be
appreciated that
the cooperating tongues and grooves can take any desired shape, and are not
limited to
the exemplary geometries given. The connecting means may be formed on the
board
by any suitable means, such as by extrusion during the sheet formation
process, or by
machining once sufficient curing has taken place. Other suitable methods of
forming
the connecting means will be readily apparent to those skilled in the art.
The fibre cement sheet preferably has a dry density of less than about 1.5
g/cm3
and more preferably less than about 1.25 g/cm3, while retaining strength
properties that
meet relevant building standards for sheet flooring designed to span spaced
apart floor
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joists. Many different additives and materials, such as density modifiers and
strength
enhancers, may be utilised in the fibre cement sheets to achieve these
desirable
characteristics such as microspheres, pearlite, volcanic ash or combinations
thereof.
These features provide a sheet with the strength properties needed for a wet
area floor. However, transportation and installation time and costs are
decreased due
to the lightweight characteristics of the material in comparison with
currently available
products. Furthermore, using this type of product removes the need to
countersink
screw holes required with higher density materials, as nails can be used to
secure the
sheets to the underlying joists, thereby significantly decreasing installation
time and
cost.
In use the fibre cement sheets are applied pre or post autoclave curing with a
sealant or sealant combination of a polymer emulsion or solution and/or a
water
repellent, such as, for example, silanes, siloxanes , waxes or stearates, to
decrease the
boards' water absorption in order to strengthen the boards and promote water
resistant
properties. The coating system can encompass air drying, multiple component
systems, reactive chemical curing, forced curing (eg heat, steam, accelerates)
or
radiation cured coatings (eg electron beam, ultra-violet, infra-red, near-
infra-red,
microwave radiation) or combinations thereof, utilising any curing/drying
techniques
for water based, solvent based or 100% solids (wet or powder) coating systems.
In one
preferred embodiment, the edges of the sheets are subsequently machined to
form the
connecting formations. However, in other embodiments, the edges of the sheets
are
machined or otherwise formed prior to the coating system being applied so that
the
edges will exhibit the same low water absorption properties as the surface of
the sheet.
Turning now to the method of installation of the system, initially a
structural
support platform is constructed from timber framing materials, steel framing
materials,
a concrete base or other suitable means to define a wet area, such as a
bathroom floor.
In the embodiment of the invention shown in figures 5 and 6, timber framing
members
10 are used to support joists 11, the upper surfaces of which collectively
form a
flooring support platform 12.
The sheets are then interlocked via the connecting means 2 and laid across the
wet area. The sheets may be connected to one another prior to laying over the
support
platform. However, in preferred embodiments, the sheets are laid in
succession, each
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being secured in turn to the previous sheet and to the underlying support
platform. In
some preferred embodiments, glue is used between the connecting formations to
secure the sheets together. There is no need to countersink screw holes in the
sheets as
the density of the board allows the sheets to be secured in place with nails
14, ideally
by pneumatic or power nailing. However, screws can be used to secure the
sheets to
the supporting subfloor or underlying framework if desired. Once the sheets
have been
secured in place, a suitable waterproofing material is placed over the support
surface in
the conventional manner. Tiles or other finishing products are then laid.
Example 1
One embodiment of the flooring sheets described herein was prepared
according to the formulation given below in Table 1. It should be understood
that the
given formulation represents only one exemplary formulation within the scope
of
United States Patent No. 6,572,697, entitled "Fiber Cement Building Materials
with
Low Density Additives" and does not constitute all embodiments of the flooring
sheets
contemplated and disclosed herein.
Portland Wood Metal
Formulation % Silica
Microspheres
Cement Pulp hydroxide
A 36.9 24.6 10 3.5 25
Table 1
Tests were conducted to ascertain the strength of the described board in
response to a uniformly distributed load (UDL), according to AS 1170.1,
"AS/NZS
Structural design actions ¨ Permanent, imposed and other actions" by forming a
timber
frame having dimensions of 2410 mm x 1210 mm constructed of 90mm x 45mm
thicknessed radiata pine framing timber, at 450mm stud centres.
The frame was sheeted with tongue and groove wet area flooring fibre cement
sheets as described herein. The sheets used in this example were nominally
900mm x
1800mm x 19mm. The sheets were trimmed to the required sample size to fit the
1210mm width of the timber frame. The resulting sheet was 1210mm x 900mm, and
the sheets were laid such that the tongue and groove joint ran across the
width of the
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frame at right angles to the longitudinal joists. The layout of the testing
material and
apparatus of Example 1 is shown in Figures 5 and 6.
A uniformly distributed load test was carried out in accordance with ASTM
E72-98, "Standard Test Method for Conducting Strength Tests of Panels for
Building
Construction." Each frame was placed over the horizontal opening of the
Uniformly
Distributed Load Testing Apparatus and it was ensured that the sample was
sealed
against the apparatus. An appropriate sealer was applied to ensure an airtight
seal
between the sample and the perimeter edges of the test chamber.
After the sample was installed into the testing apparatus, the air within the
test
chamber was evacuated, thereby inducing a uniformly distributed load to the
sample.
The load applied was monitored both by a water manometer, and a pressure
transducer
connected to an appropriate data acquisition system. The resulting test
thereby applied
a suction pressure to the underside of the test sample and thus produced a
uniformly
distributed load.
Linear variable differential transformers (LVDTs) 13 were used in conjunction
with the computerised data acquisition system to capture the deflection data.
The
LVDTs were placed midway between the studs to measure the maximum deflection
of
the sheets.
The test was run again, after the sample had been saturated with water as per
the testing standards. The edge of the frame was adequately sealed against the
sample
to provide a water-tight seal. The frame was then filled with water, and a
minimum
25mm head of water was maintained for a minimum of 7 days. The water was then
drained and the test was performed substantially as described above. The
results of the
dry and wet deflection tests are shown in the Table 2 below.
Deflection (mm)
Board Pressure LVDT 1 LVDT 2 LVDT 3 LVDT 4 Average
Average
Condition (kPa) centre joint joint centre Displacement Moisture
(mm) (mm) (mm) (mm) (mm)
Content
Dry (as 9.72 8.1 7.1 3.2 5.9 6.1
10.8%
received)
Saturated 9.79 3.7 7.4 7.3 7.2 6.4
35.7%
Table 2
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The test was continued until the uniform pressure exceeded 9.7 kPa, at which
point the pressure was relieved and the test was completed. According to the
data
presented above, it is clearly seen that the 19mm tongue and groove fibre
cement wet
area flooring, installed on joists at 450mm centres and saturated with water,
was able
to withstand an average UDL value in excess of 9.7kPa, which far exceeds the
51(Pa
requirements of AS/NZS 1170.1. Furthermore, the floor sheet and flooring
configuration described above meets the flooring imposed load concentrated
actions
requirements for domestic and residential activities described in AS/NZS
1170.1.
Never before to the applicant's knowledge has such a fibre cement wet area
flooring material been able to withstand such a high load, yet maintain a dry
density
below 1.25g/cm3 to accommodate installation methods such as nailing. The
strength
and waterproof properties of the fibre cement sheet also make it suitable for
use in
external wet areas such as decks and other areas of residential housing
typically
exposed to moist floor areas.
It will be appreciated that the invention provides modular flooring system
that
is lightweight, nailable, resistance to moisture absorption, and relatively
easy to
transport and install. Furthermore, the flooring system reduces the need for
the use of
trimmers, and the chemical structure of the fibre cement sheet significantly
decreases
the likelihood of swelling if the sheet comes into contact with water. In
these and
other respects, the invention represents a practical and commercially
significant
improvement over the prior art.
Although the invention has been described with reference to specific examples,
it will be appreciated by those skilled in the art that the invention may be
embodied in
many other forms.
