U.S. patent application number 10/784091 was filed with the patent office on 2005-09-08 for drywall joint construction and method.
This patent application is currently assigned to Hamilton Coatings, LLC. Invention is credited to Hamilton, Kurt.
Application Number | 20050193668 10/784091 |
Document ID | / |
Family ID | 34911417 |
Filed Date | 2005-09-08 |
United States Patent
Application |
20050193668 |
Kind Code |
A1 |
Hamilton, Kurt |
September 8, 2005 |
Drywall joint construction and method
Abstract
A drywall joint construction and method consisting essentially
of abutting drywall boards having a lengthwise crack therebetween
and a joint finishing system formed within the crack to complete
the drywall joint construction such that a flexible layer defines
the joint's center-line surface. Where the edges of the drywall
boards are tapered, the resulting channel is filled with a taping
compound and a tape forms the flexible layer covering the taping
compound so as to flush the joint finishing system with the drywall
boards. Where the drywall boards are non-tapered, the resulting
slit therebetween may be filled with taping compound and a tape may
again form the flexible layer covering the taping compound and
flushing the joint finishing system with the abutting drywall
boards, or the slit may be filled with a flexible compound that
also forms the flexible layer and flushes the joint finishing
system with the drywall boards.
Inventors: |
Hamilton, Kurt; (Orange,
CA) |
Correspondence
Address: |
MIND LAW FIRM
3140 RED HILL AVENUE
SUITE 150
COSTA MESA
CA
92626
US
|
Assignee: |
Hamilton Coatings, LLC
|
Family ID: |
34911417 |
Appl. No.: |
10/784091 |
Filed: |
February 23, 2004 |
Current U.S.
Class: |
52/371 |
Current CPC
Class: |
E04F 13/042
20130101 |
Class at
Publication: |
052/371 |
International
Class: |
E04B 002/00 |
Claims
What is claimed is:
1. A drywall joint construction consisting essentially of: a first
drywall board having a first lengthwise edge and an
outwardly-facing first planar surface; a second drywall board
having a second lengthwise edge and an outwardly-facing second
planar surface, the second drywall board being positioned adjacent
the first drywall board such that the first and second lengthwise
edges are brought into substantially abutting contact so as to form
a lengthwise crack between the first and second planar surfaces, a
center-line surface of the joint construction being defined as the
outwardly-facing surface directly over the crack and exposed for
surface treatment; and a joint finishing system installed within
the crack to complete the drywall joint construction, the system
including a flexible layer forming the center-line surface.
2. The construction of claim 1 wherein: the first lengthwise edge
is tapered inwardly from the first planar surface and the second
lengthwise edge is tapered inwardly from the second planar surface
such that the crack is configured as an outwardly-opening channel
having opposite angled channel sides; and the joint finishing
system comprises: a taping compound filling the channel so as to
cover the channel sides; and a tape forming the flexible layer and
covering the taping compound so as to flush the joint finishing
system with the first and second planar surfaces.
3. The construction of claim 2 wherein the taping compound
comprises a joint cement.
4. The construction of claim 3 wherein the joint cement is a
non-shrinking formulation.
5. The construction of claim 2 wherein: the tape is configured with
opposite first and second marginal edges; and the joint finishing
system further comprises a skim coat applied over the marginal
edges so as to blend the tape with the first and second planar
surfaces.
6. The construction of claim 1 wherein: the first lengthwise edge
is substantially perpendicular to the first planar surface and the
second lengthwise edge is substantially perpendicular to the second
planar surface such that the crack is configured as an
outwardly-opening slit; and the joint finishing system comprises: a
taping compound filling the slit; and a tape forming the flexible
layer and covering the taping compound so as to flush the joint
finishing system with the first and second planar surfaces.
7. The construction of claim 6 wherein the taping compound
comprises a joint cement.
8. The construction of claim 6 wherein the taping compound
comprises a flexible compound.
9. The construction of claim 6 wherein: the tape is configured with
opposite first and second marginal edges; and the joint finishing
system further comprises a skim coat applied over the marginal
edges so as to blend the tape with the first and second planar
surfaces.
10. The construction of claim 1 wherein: the first lengthwise edge
is substantially perpendicular to the first planar surface and the
second lengthwise edge is substantially perpendicular to the second
planar surface such that the crack is configured as an
outwardly-opening slit; and the joint finishing system comprises a
flexible compound forming the flexible layer and filling the slit
so as to flush the joint finishing system with the first and second
planar surfaces.
11. The construction of claim 10 wherein the flexible compound
comprises a non-shrinking formulation.
12. A drywall joint construction consisting essentially of: a first
drywall board having a first lengthwise edge and an
outwardly-facing first planar surface, the first lengthwise edge
tapering inwardly from the first planar surface; a second drywall
board having a second lengthwise edge and an outwardly-facing
second planar surface, the second lengthwise edge tapering inwardly
from the second planar surface, the second drywall board being
positioned adjacent the first drywall board such that the first and
second lengthwise edges are brought into substantially abutting
contact so as to form a lengthwise crack between the first and
second planar surfaces configured as an outwardly-opening channel
having opposite angled channel sides; a taping compound filling the
channel so as to cover the channel sides; a tape covering the
taping compound so as to flush the joint construction with the
first and second planar surfaces, the tape being configured with
opposite first and second marginal edges; and a skim coat applied
over the marginal edges so as to blend the tape with the first and
second planar surfaces.
13. A drywall joint construction consisting essentially of: a first
drywall board having a first lengthwise edge and an
outwardly-facing first planar surface, the first lengthwise edge
being substantially perpendicular to the first planar surface; a
second drywall board having a second lengthwise edge and an
outwardly-facing second planar surface, the second lengthwise edge
being substantially perpendicular to the second planar surface, the
second drywall board being positioned adjacent the first drywall
board such that the first and second lengthwise edges are brought
into substantially abutting contact so as to form a lengthwise
crack between the first and second planar surfaces configured as an
outwardly-opening slit; a taping compound filling the slit; a tape
covering the taping compound so as to flush the joint construction
with the first and second planar surfaces, the tape being
configured with opposite first and second marginal edges; and a
skim coat applied over the marginal edges so as to blend the tape
with the first and second planar surfaces.
14. The construction of claim 13 wherein the taping compound
comprises a joint cement.
15. The construction of claim 13 wherein the taping compound
comprises a flexible compound.
16. A drywall joint construction consisting essentially of: a first
drywall board having a first lengthwise edge and an
outwardly-facing first planar surface, the first lengthwise edge
being substantially perpendicular to the first planar surface; a
second drywall board having a second lengthwise edge and an
outwardly-facing second planar surface, the second lengthwise edge
being substantially perpendicular to the second planar surface, the
second drywall board being positioned adjacent the first drywall
board such that the first and second lengthwise edges are brought
into substantially abutting contact so as to form a lengthwise
crack between the first and second planar surfaces configured as an
outwardly-opening slit; and a flexible compound filling the slit so
as to flush the joint construction with the first and second planar
surfaces.
17. A method of forming a drywall joint consisting essentially of
the steps of: positioning a first drywall board having a first
lengthwise edge and an outwardly-facing first planar surface
against a support structure; positioning a second drywall board
having a second lengthwise edge and an outwardly-facing second
planar surface against the support structure such that the second
drywall board is adjacent the first drywall board and the first and
second lengthwise edges are brought into substantially abutting
contact so as to form a lengthwise crack between the first and
second planar surfaces, a center-line surface of the drywall joint
being defined as the outwardly-facing surface directly over the
crack and exposed for surface treatment; and filling the crack with
a flexible compound so as to form the center-line surface and to
flush the drywall joint with the first and second planar
surfaces.
18. A method of forming a drywall joint consisting essentially of
the steps of: positioning a first drywall board having a first
lengthwise edge and an outwardly-facing first planar surface
against a support surface; positioning a second drywall board
having a second lengthwise edge and an outwardly-facing second
planar surface against the support surface such that the second
drywall board is adjacent the first drywall board and the first and
second lengthwise edges are brought into substantially abutting
contact so as to form a lengthwise crack between the first and
second planar surfaces, a center-line surface of the drywall joint
being defined as the outwardly-facing surface directly over the
crack and exposed for surface treatment; filling the crack with a
taping compound; taping over the taping compound with a drywall
tape so as to form the center-line surface and to flush the drywall
joint with the first and second planar surfaces; and applying a
skim coat over opposite first and second marginal edges of the tape
so as to blend the tape with the first and second planar
surfaces.
19. A method of forming a drywall joint consisting essentially of
the steps of: positioning a first drywall board against a support
surface, the first drywall board having an outwardly-facing first
planar surface and a first lengthwise edge tapered inwardly from
the first planar surface; positioning a second drywall board
against the support surface, the second drywall board having an
outwardly-facing second planar surface and a second lengthwise edge
tapered inwardly from the second planar surface, such that the
second drywall board is adjacent the first drywall board and the
first and second lengthwise edges are brought into substantially
abutting contact so as to form between the first and second planar
surfaces a lengthwise outwardly-opening channel having opposite
angled channel sides, a center-line surface of the drywall joint
being defined as the outwardly-facing surface directly over the
channel and exposed for surface treatment; filling the channel with
a taping compound so as to cover the channel sides; taping over the
taping compound with a drywall tape so as to form the center-line
surface and to flush the drywall joint with the first and second
planar surfaces; and applying a skim coat over opposite first and
second marginal edges of the tape so as to blend the tape with the
first and second planar surfaces.
Description
BACKGROUND OF THE INVENTION
INCORPORATION BY REFERENCE
[0001] Applicant hereby incorporates herein by reference any and
all U.S. patents and U.S. patent applications cited or referred to
in this application.
[0002] 1. Field of the Invention
[0003] This invention relates generally to interior drywall, and
more particularly to drywall joint constructions and methods.
[0004] 2. Description of Related Art
[0005] In the interior drywall field, the conventional drywall
joint is formed between drywall boards having tapered abutting
edges so as to form an outwardly-facing recess along the joint that
must be filled in. Conventional joint cement compound for filling
the recess is formulated to be soft for easy sanding when finishing
the joint. Unfortunately, as a result of this formulation, the
typical conventional joint cement compound has little cohesion or
adhesion to the underlying drywall boards, is weak and brittle, and
is prone to cracking upon expansion or contraction of the drywall
joint. Repair of such failed joints can be costly, particularly
after the interior is completed and the building occupied.
[0006] Beyond these concerns relating to the structural integrity
of the conventional drywall joint, the use of conventional joint
cement compound also presents aesthetic problems for the finished
joint, including the common problem of surface cracking. Because
the joint cement is, again, soft and weak, when joint cement is at
the surface of a drywall joint directly over the recess or crack
between abutting drywall boards, center-line cracking along the
recess often occurs as the joint is stressed and the drywall boards
move relative to one another. Further, the conventional joint
cement compound at the surface of the drywall joint also tends to
absorb too much paint so as to leave different sheens on the wall
or ceiling, commonly referred to in the art as flashing or
photographing, and even allows for delamination between the drywall
board, texture and paint.
[0007] Once a first coat of conventional joint cement compound is
applied to the recess in the drywall joint, the typical drywall
joint is completed by applying drywall tape or paper along the
joint and then applying two top coats of conventional joint cement
compound over the tape to flush the joint with the abutting drywall
boards. Beyond the structural and aesthetic short-comings of this
typical drywall joint, as explained previously, this joint
finishing process creates other logistical and economic problems as
well. First, the thick coats of conventional joint cement compound
must be allowed to dry before the joint can be completed, requiring
multiple trips to the work-site. And second, the number of coats of
conventional joint cement compound adds further cost to the
finished drywall joint both in terms of materials and labor.
[0008] The following art defines the present state of this
field:
[0009] U.S. Pat. No. 2,323,963 to Ames is directed to a combined
plastic and tape applicator which will combine the steps of
applying plastic in the groove between adjacent wallboards and
covering the plastic with tape for reinforcing purposes by first
coating the tape with plastic and then applying it to the joint
between two adjacent wallboard sections. This method of application
not only combines two of the steps into one, but provides a more
even distribution of the plastic that lies between the tape and the
wallboard, thus increasing the adhesive contact between the plastic
and the wallboard and thereby strengthening the entire joint.
[0010] U.S. Pat. No. 3,180,058 to Tillisch et al. is directed to a
joint structure for plasterboard wherein there is provided
plasterboard having a plurality of shallow, discontinuous
indentations in multiple rows in at least one surface adjacent the
edge thereof, and adapted to retain joint cement applied to such
surface to insure a joint which is satisfactory and of pleasing
appearance.
[0011] U.S. Pat. No. 3,708,935 to Kossuth et al. is directed to a
predecorated wallboard for forming simulated monolithic
predecorated wall construction composed of an elongated rectangular
core panel including a set gypsum core enclosed on its two opposite
sides and two longitudinal edges with a paper facing layer and
having on its front side a flat central surface arranged between
recessed marginal surfaces extending from the flat surface to the
opposite longitudinal edges of the panel and tapering edgewise
toward the rear side of the panel, and a decorative sheet including
a cloth backing layer laminated only to the flat surface of the
paper facing layer on the front side of the panel throughout the
length of such front side and an outer polyvinyl chloride layer
forming a decorative front wall surface, such sheet also including
a narrower flap extending over one of the marginal surfaces but
terminating flush with the adjacent longitudinal edge of the panel
and a wider flap extending over the opposite marginal surface
beyond the opposite longitudinal edge of the panel. Each wallboard
is adapted to form a joint with an adjacent wallboard, such as a
flat joint wherein the adjacent longitudinal edges of the panels
are arranged in abutting relationship and the front sides thereof
are flush, with the adjacent marginal surfaces thereof forming
beneath adjacent narrower and wider flaps a shallow V-shaped recess
or space to be filled to the level of the flat surfaces of the
panels with a hardened joint cement layer to which the narrower and
wider flaps are adhered as well as to each other in overlapping
relationship over the marginal surface underlying the narrower
flap, the joint being completed by cutting through the overlapping
portions of both flaps, by removing the overlapping and overlapped
marginal edge portions of the overlying and underlying flaps
respectively to cause the narrow flap to terminate short of the
adjacent longitudinal edge of the underlying panel, and by
readhering the remainder of the overlying flap to cause the wider
flap to extend into edge abutting and flush relationship with the
narrower flap to form a practically invisible seam.
[0012] U.S. Pat. No. 4,122,222 to Parker is directed to a method
and a preformed laminate useful in various forms for repairing
holes and covering joints in drywall. The laminate comprises a
sheet material backing having an overlay of plaster joint compound,
or the like. The overlay has an outwardly tapered thickness. The
laminate may be in circular, strip, or other form. The backing
material is secured over the hole or joint, as the case may be, and
a small amount of drywall joint compound is added around the
perimeter to blend the patch into the wall surface.
[0013] European Patent App. No. 0,456,435 A1 to Retti is directed
to an apparatus for taping joints between pieces of wallboard
comprising a taping head, slidingly contactable with a wall, for
substantially simultaneously applying a first layer of a joint
compound to a joint between pieces of wallboard, embedding a
wallboard tape in the first layer of the joint compound, and
overcoating the embedded wallboard tape with at least one
additional layer of the joint compound, a handle connected to the
taping head, for supporting the taping head, the handle being
manually graspable by an operator, the handle having a fluid
conduit formed therein for passing joint compound to the taping
head, a tape supply mounted on the handle for supplying wallboard
tape to the taping head, a backpack, wearable by the operator, for
supporting a supply of the joint compound and for producing a
pressurized stream of the joint compound, and a flexible connecting
means for fluidically interconnecting the backpack and the fluid
conduit to pass the pressurized stream of the joint compound from
the backpack to the fluid conduit.
[0014] U.S. Pat. No. 5,628,159 to Younts is directed to an improved
joint strip for concealing a joint formed between two panels of
adjacent wallboards formed of a flexible support strip capable of
withstanding day-to-day wall vibrations and a rib adhered on one
side of the support strip such that it extends the length of the
support strip. The support strip may be formed from a variety of
materials such as synthetic fibers, cellulose fibers, non-woven
paper, plastic fibers, fiberglass, specially treated fabric, and
mixtures thereof. The joint strip possesses superior strength and
flexibility properties thus eliminating the need to use
predecorated wallboard for forming a monolithic appearing wall.
[0015] Thus, the prior art described above teaches a combined
plastic and tape applicator, a joint structure for plasterboard, a
simulated monolithic predecorated wall construction, a laminate and
method for drywall holes and joints, a wallboard taping process and
apparatus therefor, and a joint strip, method of forming a wall
using the joint strip, and wall made therefrom, but does not teach
an improved drywall joint construction and method that both
minimizes or altogether eliminates the conventional weak, chalky
joint compound from the drywall joint, particularly at the joint
surface, and provides a stronger, more attractive, and more
economical joint. The present invention fulfills these needs and
provides further related advantages as described in the following
summary.
SUMMARY OF THE INVENTION
[0016] The present invention teaches certain benefits in
construction and use which give rise to the objectives described
below.
[0017] The present invention is generally directed to a drywall
joint construction and method consisting essentially of a first
drywall board having a first lengthwise edge and an
outwardly-facing first planar surface, a second drywall board
having a second lengthwise edge and an outwardly-facing second
planar surface, the second drywall board being positioned adjacent
the first drywall board such that the first and second lengthwise
edges are brought into substantially abutting contact so as to form
a lengthwise crack between the first and second planar surfaces,
and a joint finishing system formed within the crack to complete
the drywall joint construction. In a first exemplary embodiment,
the first and second lengthwise edges of the drywall boards are
tapered so as to form the crack as a channel, wherein the joint
finishing system is configured as a taping compound filling the
channel and a tape forming the flexible layer and covering the
taping compound so as to flush the joint finishing system with the
first and second planar surfaces of the abutting drywall boards. In
the second and third exemplary embodiments, non-tapered drywall
boards are employed such that the crack is formed as a slit. In the
second embodiment, the slit is filled with taping compound and a
tape again forms the flexible layer covering the taping compound
and flushing the joint finishing system with the abutting drywall
boards. In the third exemplary embodiment, a flexible compound
forms the flexible layer and fills the slit so as to flush the
joint finishing system with the drywall boards. Common to each of
the three exemplary embodiments, a flexible layer rather than joint
cement is employed at the center-line surface of the drywall joint
construction, yielding a stronger, more crack-resistant and more
aesthetically-pleasing drywall joint construction.
[0018] A primary objective of the present invention is to provide a
drywall joint construction and method of use of such construction
that provides advantages not taught by the prior art.
[0019] Another objective is to provide such an invention capable of
reducing the amount of joint compound in a drywall joint.
[0020] Another objective is to provide such an invention capable of
eliminating the conventional joint cement compound at the
center-line surface of a drywall joint.
[0021] Yet another objective is to provide such an invention
capable of eliminating the conventional joint cement compound from
the crack of a drywall joint.
[0022] A further objective is to provide such an invention capable
of eliminating the conventional joint cement compound at the
surface of a drywall joint.
[0023] A still further objective is to provide such an invention
capable of eliminating the conventional joint cement compound from
a drywall joint.
[0024] Other features and advantages of the present invention will
become apparent from the following more detailed description, taken
in conjunction with the accompanying drawings, which illustrate, by
way of example, the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The accompanying drawings illustrate the present invention.
In such drawings:
[0026] FIG. 1 is a perspective view of an exemplary embodiment of a
drywall joint of the present invention;
[0027] FIG. 2 is an enlarged cross-sectional view thereof taken
along line 2-2 of FIG. 1;
[0028] FIG. 3 is a cross-sectional view of a second exemplary
embodiment of a drywall joint of the present invention;
[0029] FIG. 4 is a cross-sectional view of a third exemplary
embodiment of a drywall joint of the present invention; and
[0030] FIG. 5 is a cross-sectional view of a prior art drywall
joint.
DETAILED DESCRIPTION OF THE INVENTION
[0031] The above described drawing figures illustrate the invention
in at least three of its preferred embodiments, which are further
defined in detail in the following description.
[0032] The present invention is generally directed to a drywall
joint construction 10 consisting essentially of a first drywall
board 20 having a first lengthwise edge 22 and an outwardly-facing
first planar surface 24, a second drywall board 30 having a second
lengthwise edge 32 and an outwardly-facing second planar surface
34, the second drywall board 30 being positioned adjacent the first
drywall board 20 such that the first and second lengthwise edges
22, 32 are brought into substantially abutting contact so as to
form a lengthwise crack 40 between the first and second planar
surfaces 24, 34, and a joint finishing system 50 formed within the
crack 40 to complete the drywall joint construction 10. Common to
the joint finishing system 50 in each of the three exemplary
embodiments shown and described, no conventional joint cement
compound of any kind is employed at the center-line surface 80 of
the drywall joint construction 10. As will be appreciated by those
skilled in the art, conventional joint cement compounds are weak
and chalky and are prone to cracking along the center-line surface
80 as the first and second drywall boards 20, 30 shift relative to
one another, so that, as explained more fully below, by removing
the conventional joint cement compound from the center-line surface
80, a stronger, more aesthetically-pleasing drywall joint
construction 10 is obtained. Thus, center-line cracking in the
joint cement compound of the conventional drywall joint is
eliminated in the present invention by eliminating the joint cement
compound from the critical center-line surface 80. Instead, a
flexible layer 60, preferably of either tape or a flexible compound
such as caulk, forms the center-line surface 80. While this is
achieved in at least three ways as disclosed by the exemplary three
embodiments, it will be further appreciated that other related
joint constructions, involving various drywall board
configurations, compounds and flexible outer layers, are possible
without departing from the spirit and scope of the present
invention.
[0033] Turning to FIG. 2, in a first exemplary embodiment of the
drywall joint construction 10 of the present invention, the first
and second drywall boards 20, 30 are shown installed in a
substantially co-planar, abutting relationship, as when drywall is
installed on an interior wall or ceiling of a building. The
abutting first and second lengthwise edges 22, 32 are tapered
inwardly from the respective first and second planar surfaces 24,
34 such that the crack is configured as an outwardly-opening
channel 40 having opposite angled channel sides 42, 44. In this
exemplary embodiment, then, the joint finishing system 50 begins
with a taping compound 52 that fills the channel 40 so as to cover
the channel sides 42, 44. Next, a flexible drywall tape 60 is
installed over the taping compound 52 so as to flush the joint
finishing system 50 with the first and second planar surfaces 24,
34. As the tape 60 is configured with opposite first and second
marginal edges 62, 64, the joint finishing system 50 may further
comprise a skim coat 70 applied over the marginal edges 62, 64 so
as to blend the tape 60 with the first and second planar surfaces
24, 34. Importantly, the center-line surface 80 of the joint
construction 10, which is defined as the outwardly-facing surface
directly over the channel 40 and which is exposed for later surface
treatment, is formed by the tape 60. No joint compound is at the
surface of the joint construction 10 over the channel 40. As will
again be appreciated by those skilled in the art, and as the test
data below confirms, a finished drywall joint construction 10
having flexible tape 60 rather than weak, chalky joint cement
compound at the center-line surface 80 over the crack 40 between
abutting drywall boards 20, 30 produces a joint that is stronger
and more crack-resistant. As such, the joint will also be more
attractive. In a preferred embodiment, such an improved drywall
joint construction 10 may also be achieved more economically than
the conventional drywall joint by employing a non-shrinking joint
cement formulation as the taping compound 52, thereby requiring
only one coat of the compound before applying the tape 60. In this
way, less material and fewer trips to the work-site may be
required, saving on material and labor costs. An exemplary
non-shrink taping compound 52 formulation includes 20-25% filler
such as calcium carbonate or gypsum, 6-8% lightweight filler such
as mica, 10-15% 3M.RTM. glass bubble, 1-5% methylcellulose, 10-20%
resin and 30-50% water by weight, though any non-shrink compound
will be sufficient. By comparison, the conventional joint cement
formulation includes 20-25% filler such as calcium carbonate or
gypsum, 6-8% lightweight filler such as mica, 5-15% attapulgite or
bentonite clay, 1-5% methylcellulose, 5-8% resin and 50-60% water
by weight. It will be appreciated by those skilled in the art that
the relatively smaller amount of water by percent weight in the
exemplary non-shrink formulation results in a taping compound 52
that shrinks relatively less when setting. It is noted that the use
of a non-shrink taping compound 52 as compared to a standard joint
cement compound is preferable only in terms of the associated
potential material and labor cost savings, but is not necessarily
preferable in any respect relating to the functional integrity of
the finished drywall joint construction 10. Rather, the use of one
or more coats of conventional joint cement compound or any other
suitable material to bring the flexible tape 60 to the center-line
surface 80 can be equally effective in the present invention.
[0034] Referring to FIG. 3, a second exemplary embodiment of the
drywall joint construction 10' of the present invention is shown as
again including first and second drywall boards 20', 30' installed
in a substantially co-planar, abutting relationship, but now with
the respective first and second lengthwise edges 22', 32' being
substantially perpendicular to the respective first and second
planar surfaces 24', 34' such that the crack between the abutting
boards 20', 30' is configured as an outwardly-opening slit 40'. The
joint finishing system 50' includes a taping compound 52' filling
the slit, which compound may be a conventional joint cement, a
non-shrinking joint compound, a flexible compound such as caulk, or
any other suitable material. By employing non-tapered drywall
boards 20', 30', it will be appreciated that the total volume to be
filled in flushing the joint is greatly reduced as compared to the
tapered drywall boards 20, 30 shown in FIGS. 1 and 2, making the
exemplary joint construction 10' of FIG. 3 even more economical.
Regarding the structural integrity of the finished joint, the joint
finishing system 50' further includes a flexible tape 60' again
covering the taping compound 52' so as to flush the joint finishing
system 50' with the first and second planar surfaces 24', 34',
though a skim coat 70' may be employed to blend the marginal edges
62', 64' of the tape 60' with the first and second planar surfaces
24', 34'. Once more, the center-line surface 80' of the joint
construction 10' is therefore formed by the tape 60', not
conventional joint cement compound, making the joint stronger and
more crack-resistant, as again demonstrated by the test data
reported and discussed below.
[0035] Turning now to FIG. 4, a third exemplary embodiment of the
drywall joint construction 10" of the present invention is shown as
including first and second drywall boards 20", 30" installed in a
substantially co-planar, abutting relationship and having
respective first and second lengthwise edges 22", 32" substantially
perpendicular to the respective first and second planar surfaces
24", 34" such that the crack between the abutting boards 20", 30"
is again configured as an outwardly-opening slit 40". The joint
finishing system 50" comprises a flexible compound 52" defining the
flexible layer 60 (FIG. 1) and filling the slit 40" so as to flush
the joint finishing system 50" with the first and second planar
drywall surfaces 24", 34". So as to more readily flush the flexible
compound 52" with the drywall surfaces 24", 34", it is preferred
that the flexible compound 52" be of a non-shrink formulation such
as a caulk or a compound including 20-25% filler such as calcium
carbonate or gypsum, 6-8% lightweight filler such as mica, 10-15%
3M.RTM. glass bubble, 1-5% methylcellulose, 30-50% resin and 10-20%
water by weight, though, again, any flexible compound will suffice.
It will be appreciated by those skilled in the art that by using a
flexible compound that is non-shrinking, time and material costs
may be saved, but the structural integrity of the finished joint
will not be substantially affected. As with the previous two
exemplary embodiments of FIGS. 2 and 3, respectively, the present
exemplary embodiment of FIG. 4 also has the critical advantage over
prior joint systems of employing a flexible layer 60 (FIG. 1), here
the flexible compound 52", at the center-line surface 80" over the
crack 40" between abutting drywall boards 20", 30", rather than
weak, chalky joint compound, so as to produce a joint construction
10" that is stronger, more crack-resistant and more attractive.
[0036] Samples of both the exemplary three drywall joint
constructions of the present invention shown in FIGS. 2-4 and the
conventional drywall joint construction shown in FIG. 5 were
evaluated for crack-resistance under the test explained below. The
conventional joint construction 110, as shown in FIG. 5, includes
abutting drywall boards 120, 130 having tapered first and second
lengthwise edges 122, 132 so as to form a channel 140 that is
partially filled in by a first taping coat 152. A drywall tape 160
is applied over the taping coat 152, and then the joint is flushed
by one or more topping coats 170 of joint cement over the tape 160.
Thus, it is clear that in the typical prior art drywall joint,
joint cement forms the center-line surface 180 directly over the
channel 140. While one topping coat 170 is shown, it is often the
case that two topping coats are required to flush the joint,
further weakening and adding more labor and material costs to the
conventional drywall joint.
[0037] In testing the various drywall joint constructions,
12".times.13" pieces of drywall boards were abutted along their
finished edges and the joints between the boards were completed
according to the three exemplary joint constructions 10, 10', 10"
of the present invention and the conventional drywall joint 110 now
used in the art. Each such assembly was laid horizontally on a
workstation such that the joint itself was positioned directly over
a vertical piston. While the edges of the respective boards
opposite the joint were held in place, the piston was caused to
gradually force the center of the assembly, or the joint,
vertically upward so as to effectively flex or bend the assembly
about the joint. Such movement of the piston was allowed to
continue until a crack visibly appeared on the surface of the
joint. The crack resistance of each joint was then quantified as
the change in position of the piston from the joint at rest to the
joint at failure, when a crack was observed. Under this test, the
conventional drywall joint 110 (FIG. 5) failed, or a crack was
observed on the joint, at between 4.5 and 5.0 mm. Comparatively, in
the first exemplary joint construction 10 of the present invention
(FIG. 2), no crack was seen until between 29.0 and 31.0 mm. And in
the second exemplary joint construction 10' (FIG. 3), no crack was
visible until the joint was flexed to between 42.0 and 43.5 mm from
its unflexed starting position, indicating that eliminating more of
the joint cement by replacing the conventional tapered drywall
boards 20, 30 (FIG. 2) with non-tapered boards 20', 30', and thus
constituting more of the joint system 50' with drywall board rather
than with joint cement, further improved the strength and
crack-resistance of the joint. In both of the first two embodiments
of the joint construction 10, 10', the crack that was observed was
in the skim coat 70, 70' used to blend the marginal edges 62, 64,
62', 64' of the tape 60, 60' with the respective planar drywall
board surfaces 24, 34, 24', 34', not along the center-line surface
80, 80' in the tape 60, 60'.
[0038] For the third exemplary joint construction 10" (FIG. 4),
wherein no joint cement is used at all, the first crack was seen at
between 210.0 and 220.0 mm, evidencing that ridding the joint
construction 10" of joint cement altogether produces the strongest,
most crack-resistant joint. While no joint should be expected to
see in normal use the kind of movement or flexure indicated, this
testing still provides a striking comparison of the
crack-resistance of the joint constructions 10, 10', 10" of the
present invention relative to a conventional drywall joint 110.
Comparatively, the testing proves that all three exemplary
embodiments of the present invention wherein the joint cement is at
least eliminated from the center-line surface of the joint yielded
significant improvements in crack-resistance over the conventional
prior art drywall joint 110.
[0039] It follows that by removing the conventional joint cement
compound from the center-line surfaces 80, 80', 80" of the drywall
joint constructions 10, 10', 10" according to the present
invention, a stronger, more crack-resistant joint is achieved.
Generally, both drywall tape and drywall board are over 300%
stronger than the typical joint cement, and flexible compounds such
as caulks can be even stronger. Thus, though it has generally
always been thought in the art that the joint cement is the
strongest part of the joint system, this is simply not the case, as
the above test data indicates. In fact, the typical joint cement is
actually designed to be weak and chalky so that it can be easily
sanded down to bring it flush with the abutting drywall boards.
These same attributes cause the joint cement to be prone to
cracking. The present invention takes advantage of a correct
understanding of the relative strengths of the components of the
typical drywall joint to beneficially remove the joint cement from
the center-line surface of the joint construction, and in two
constructions 10', 10" effectively remove the joint cement from the
joint system 50', 50" altogether, so as to produce an improved,
stronger and more crack-resistant drywall joint construction.
[0040] Moreover, the problem of surface cracking, which makes a
drywall joint unsightly and costly to repair, is effectively
eliminated by the joint constructions 10, 10', 10" of the present
invention. While having the soft and weak joint cement at the
surface of a drywall joint directly over the recess or crack
between abutting drywall boards allows center-line cracking to
often occur along the recess as the joint is stressed and the
drywall boards move relative to one another, the joint
constructions 10, 10', 10" of the present invention are stronger
and greatly reduce the risk of such surface cracking by entirely
removing the joint cement from the center-line surface 80, 80',
80". Further, as is known in the art, the conventional joint cement
compound at the surface of the typical drywall joint 110 also tends
to absorb too much paint so as to leave different sheens on the
wall or ceiling, commonly referred to as flashing or photographing.
The joint constructions 10, 10', 10" of the present invention
eliminate this problem as well, again, by entirely removing the
absorptive joint cement from the center-line surface 80, 80', 80".
The risk of delamination between the drywall board, texture and
paint possible in the conventional drywall joint 110 employing
joint cement 170 at the surface 180 is also effectively eliminated
in the joint constructions 10, 10', 10" of the present invention.
And regarding the aesthetics of the drywall joint, it is preferred,
though not necessary in practicing the present invention, that an
elastomeric paint (not shown) be employed in covering the joint
that has a crack resistance equal to or exceeding that of the
joint, or that has a flexibility or elongation meeting or exceeding
that of the respective joint construction. In this way, the paint
would be unlikely to crack before the joint ever would.
[0041] Beyond these structural and aesthetic considerations, those
skilled in the art will appreciate that the joint constructions 10,
10', 10" of the present invention also provide economic benefits
over the conventional drywall joint 110. As seen, even in the first
and second exemplary joint constructions 10, 10' wherein a taping
compound 52, 52' is used to fill in the space 40, 40' between
abutting drywall boards 20, 30, 20', 30', because only one taping
coat 52, 52' and a thin skim coat 70, 70' are generally required to
complete the joint finishing system 50, 50', as compared to the
usual taping coat 152 and two topping coats 170 required in the
conventional drywall joint 110, savings in time and material costs
are gained. Moreover, when non-tapered drywall boards 20', 30',
20", 30" are employed, as in the second and third joint
constructions 10', 10" of the present invention, the space 40', 40"
to be filled in is reduced, thereby reducing the materials required
and, accordingly, the labor needed to install the materials. In the
third exemplary joint construction 10", the elimination of the
drywall tape and drywall joint compound altogether provides even
further savings in terms of both materials and labor.
[0042] Therefore, the present invention of an improved drywall
joint construction and method both minimizes or altogether
eliminates the conventional weak, chalky joint cement compound from
the drywall joint, particularly at the joint surface where cracking
is most likely and most detrimental, and provides a stronger, more
attractive, and more economical joint. While the invention has been
described with reference to at least three preferred embodiments,
it is to be clearly understood by those skilled in the art that the
invention is not limited thereto. Rather, the scope of the
invention is to be interpreted only in conjunction with the
appended claims and it is made clear, here, that the inventor
believes that the claimed subject matter is the invention.
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