U.S. patent application number 12/135143 was filed with the patent office on 2008-10-09 for joint cement-free drywall joint construction and method.
Invention is credited to Kurt Hamilton.
Application Number | 20080245026 12/135143 |
Document ID | / |
Family ID | 39825739 |
Filed Date | 2008-10-09 |
United States Patent
Application |
20080245026 |
Kind Code |
A1 |
Hamilton; Kurt |
October 9, 2008 |
JOINT CEMENT-FREE 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 drywall boards are
non-tapered, the resulting crack therebetween 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: |
JEROMYE V. SARTAIN;MIND LAW FIRM
2424 S.E. BRISTOL STREET, SUITE 300
NEWPORT BEACH
CA
92660
US
|
Family ID: |
39825739 |
Appl. No.: |
12/135143 |
Filed: |
June 6, 2008 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10784091 |
Feb 23, 2004 |
|
|
|
12135143 |
|
|
|
|
Current U.S.
Class: |
52/698 ;
52/742.16 |
Current CPC
Class: |
E04F 13/0891 20130101;
E04F 13/04 20130101 |
Class at
Publication: |
52/698 ;
52/742.16 |
International
Class: |
E04C 2/34 20060101
E04C002/34 |
Claims
1. An interior drywall joint construction consisting essentially
of: a non-recessed 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 non-recessed 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
substantially 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 flexible
compound filling the crack so as to form the center-line surface
and flush the joint construction with the first and second planar
surfaces.
2. The construction of claim 1 wherein the flexible compound
comprises: 20 to 25 percent by weight filler; 6 to 8 percent by
weight lightweight filler; 10 to 15 percent by weight glass
bubbles; 1 to 5 percent by weight methylcellulose; 30 to 50 percent
by weight resin; and 10 to 20 percent by weight water.
3. The construction of claim 2 wherein the filler is selected from
the group consisting of calcium carbonate and gypsum.
4. The construction of claim 2 wherein the lightweight filler is
mica.
5. The construction of claim 2 wherein the glass bubbles have a
T.sub.g of greater than about -25.degree. C.
6. An interior drywall joint construction consisting essentially
of: a support structure having an interior side; a non-recessed
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, the
first drywall board being installed on the interior side of the
support structure; a non-recessed 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 installed on the interior side of the support structure
substantially 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 flexible
compound filling the crack in a single coat so as to form the
center-line surface and flush the joint construction with the first
and second planar surfaces, the flexible compound comprising: 20 to
25 percent by weight filler; 6 to 8 percent by weight lightweight
filler; 10 to 15 percent by weight glass bubbles, the glass bubbles
having a T.sub.g of greater than about -25.degree. C.; 1 to 5
percent by weight methylcellulose; 30 to 50 percent by weight
resin; and 10 to 20 percent by weight water.
7. A method of forming a drywall joint consisting essentially of
the steps of: installing a non-recessed first drywall board having
a first lengthwise edge and an outwardly-facing first planar
surface on an interior side of a support structure, the first
lengthwise edge being substantially perpendicular to the first
planar surface; installing a non-recessed second drywall board
having a second lengthwise edge and an outwardly-facing second
planar surface on the interior side of the support structure such
that the second drywall board is substantially adjacent the first
drywall board, the second lengthwise edge being substantially
perpendicular to the second planar surface, 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 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 flush
the drywall joint with the first and second planar surfaces.
8. The method of claim 7 wherein the step of filling the crack with
a flexible compound comprises a single coat.
Description
RELATED APPLICATIONS
[0001] This is a continuation-in-part application of a prior filed
and currently pending application having Ser. No. 10/784,091 and a
filing date of Feb. 23, 2004.
INCORPORATION BY REFERENCE
[0002] Applicant hereby incorporates herein by reference any and
all U.S. patents and U.S. patent applications cited or referred to
in this application.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] This invention relates generally to interior drywall, and
more particularly to drywall joint constructions and methods.
[0005] 2. Description of Related Art
[0006] 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.
[0007] 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.
[0008] 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.
[0009] The following art defines the present state of this
field:
[0010] 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.
[0011] 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.
[0012] 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.
[0013] 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.
[0014] 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.
[0015] 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.
[0016] U.S. Pat. No. 2,427,879 to Robertson et al. is directed to
an improved surfacing material made from laminated sheets of
fireproof sheet-like material particularly those formed from
calcified gypsum. It particularly relates to a novel method of
joining sheets of structural material together to form a proper
type of weather barrier with a minimum of effort.
[0017] U.S. Pat. No. 3,749,692 to Scocos et al. is directed to a
plasticized aqueous latex caulk containing solid filler through
which paintability of the cured surface can be improved by using as
about 60-80 weight percent of the plasticizer components a
polybutene having an average molecular weight of about 400-500,
viscosity of about 150-300 centistokes at 100.degree. F., and pour
point not substantially higher than about -20.degree. F.
[0018] U.S. Pat. No. 6,884,830 to Hornaman is directed to a
flexible setting type hydraulic joint compound and a method of
forming flexible joints. The flexible joint compound of this
invention primarily contains 2 to 20 parts by weight of an emulsion
polymer having a T.sub.g that is less than about -40.degree. C.,
and 22 to 44 parts by weight of total water, based on 100 parts by
weight calcium sulfate hemihydrate filler. It can be applied to
joints between two adjacent sheets of gypsum board to form a
flexible joint that is resistant to cracking.
[0019] U.S. Pat. No. 5,869,166 to Caldwell and U.S. Pat. No.
6,749,920 to Caldwell et al. are directed to using a combination of
relatively coarse filler and latex binder, a high solids coating
which has a minimum solids content of about 60% by volume, can be
produced with a relatively low working viscosity. These very high
solids coatings can be applied in thick single layers and oven
cured without cracking. They maintain more than 80% of their
original wet thickness. The resulting coating provides an extremely
hard and durable surface, even on relatively soft mineral fiber
board ceiling tiles or wall panels.
[0020] U.S. Pat. Nos. 4,743,475 and 4,820,754 to Negri et al. are
directed to a paint made from a low cost, easily dispersible powder
in which the pigment volume concentration is about 70% to about
75%, by which the unequal porosity and different textures of a
drywall reinforced with joint tape and joint compound are
concealed. A vinyl acetate/ethylene copolymer serves as the
principle binder and a water soluble cellulose ether thickens the
water dispersion of kaolin, attapulgus clay, mica, sodium potassium
aluminum silicate and calcium carbonate.
[0021] U.S. Pat. No. 6,207,742 to Boldt is directed to a
two-component aqueous composition for thick horizontal markings on
roads or other traffic areas. One component includes a
drying-accelerated binder, pigments, pulverulent fillers and
additives, while the other component includes coarse fillers. The
composition is very high solids and fast drying without the
cracking, smearing, and dirt adhesion typical of thick film traffic
markings.
[0022] U.S. Pat. No. 4,735,027 to Evans et al. is directed to a
coating for a wallboard comprising silica sand, cement and a
particulate, non-fibrous filler, where the ratio of the average
sand diameter to the average filler diameter is within the range of
from about 40:1 to about 20:1.
[0023] U.S. Pat. No. 4,904,709 to Hermele is directed to a
lightweight synthetic stucco composition which includes a mixture
comprising a latex emulsion, water and titanium dioxide as well as
a number of additives for adjusting the properties of the mixture
and further including an admixture of hollow microspheres and
macrospheres, with the microspheres having a diameter of about 10
to 150 microns and the macrospheres having a diameter of from 300
to 2000 microns, the admixture comprising between 30 and 60% of the
finished composition. Utilizing a mixture of microspheres and
macrospheres produces a substantial weight savings which makes the
synthetic stucco composition easier to apply, less costly to
transport and less demanding on the structure of the building. In
addition, the particular combination of spherical structures
provides a uniform tightly knit appearance free of pinholes and
craters as the smaller particles fill the void spaces between the
larger ones with the spherical shape of the particles allowing them
to pack in a very tight arrangement. Where it is desired to have a
more textured appearance, between 1 to 25% by weight coarse silica
sand may be added to the admixture, with the coarse silica sand
having a particle size from 1500 to 2000 microns.
[0024] U.S. Pat. No. 6,376,589 to Tanaka et al. is directed to a
coating composition comprising a binder component consisting of
(A') hydroxyl group-containing polyester resin having a number
average molecular weight of 2,000-20,000, glass transition
temperature of -40.degree. C. to 30.degree. C. and hydroxyl value
of 5-95 mgKOH/g, (B) blocked polyisocyanate compound blocked with
.epsilon.-caprolactam, and the equivalent ratio of the blocked
isocyanate groups in said blocked polyisocyanate compound (B)/the
hydroxyl groups in said polyester resin (A) being in the range of
0.7-1.2, and 0.5-30 parts by weight of said resin fine particles
(C) with an average particle diameter of 8-70 .mu.m, which do not
completely melt at the time of coating film curing, per 100 parts
by weight of said binder component. Said coating composition can
form a coating film having excellent popping resistance, hardness,
processibility, anti-tackiness, blocking resistance and curability
by a high temperature short time baking.
[0025] U.S. Pat. No. 6,531,537 to Friel et al. is directed to
methods of providing a paint line containing a latex polymeric
binder. A range of paints can be formulated using sets of
prepaints, at least one of which contains a latex polymeric binder.
The paints may be applied as architectural coatings, industrial
coatings, graphic arts coating, elastomeric coatings, and
non-cementitious, aggregate finish coatings suitable for
application on a wall directly or as a topcoat in exterior
insulation finishing systems.
[0026] U.S. Pat. No. 5,308,397 to Whatcott is directed to a stucco
coating for interior and exterior walls of buildings that provides
increased bonding strength over the prior art.
[0027] U.S. Pat. No. 6,120,837 to Atsuyo et al. is directed to a
method for priming an uneven surface of a blank using a novel
"thermally expansible spray putty". This spray putty is prepared by
mixing a priming paint for the blank with thermally expansible
micro-capsules in amount of 0.5 to 10 weight % of the solid matter
of the priming paint. The thermally expansible spray putty is
preferably conditioned with an exclusive thinner to a high viscous
state enabling it to be air-sprayed. Shell walls of the
micro-capsules soften at a temperature below the setting
temperature of a thermosetting paint to be used in finish painting
of the blank. After the blank being treated by degreasing, drying
and the like, the uneven surface of the blank is coated with the
thermally expansible spray putty by spraying. After suitably
setting the coated spray putty, it is dried by heating so as to
expand the micro-capsules to obtain a substantially smooth surface
of the blank. After simply grinding the surface, a smooth finish
surface is obtained only by intercoating or finish painting it,
which is sufficiently endurable to practical use.
[0028] U.S. Patent App. Pub. No. 20020108342 to Henits is directed
to the preparation of a pair of abutting straight edges of a pair
of wallboard panels for receiving spackle to provide smooth planar
butt joints including the use of a rotary tool having a tool bit to
form a channel extending on both sides of the butt joint after the
wallboard panels have been installed. After the formation of the
channel, spackling of the butt joint in a conventional manner
results in a smooth planar finished surface.
[0029] U.S. Patent App. Pub. No. 20030084633 to Zuber et al. is
directed to a construction assembly for interior works, comprising:
prefabricated elements, preferably flat prefabricated elements e.g.
gypsum fiberboards, cement fiberboards, gypsum wall boards or
plaster boards, wherein said prefabricated elements comprise a
coating layer formed of at least one skim coat deposited on said
prefabricated elements by a coating device; and at least one
jointing material, e.g. a sealing coat, joint coat and/or joint
pointing coat, which joints adjacent said prefabricated elements to
form a substantially plane outer surface comprising the visible
surface of said at least one jointing material and the visible
surface of the skim coated prefabricated elements, wherein said at
least one jointing material and said at least one skim coat
comprise a mineral filler, a binder and water; and wherein the
composition of said at least one jointing material and said at
least one skim coat are adapted to each other, whereby said at
least one jointing material and said skim coat form, both in a dry
state, a substantially homogeneous outer surface having over
substantially all its surface at least one of the parameters
comprised in the group consisting of coloration, reflectance factor
and surface water absorbability which is substantially homogeneous
over said surface; and whereby said outer surface is ready to be
decorated. For instance, said at least one of the parameters
differs by no more than 10%, preferably no more than 5%, at
different parts of the overall surface, so that at least 90%,
preferably at least 95%, homogeneity is achieved.
[0030] U.S. Patent App. Pub. No. 20050072114 to Shiao et al. is
directed to solar-reflective roofing granules having deep-tone
colors formed by coating base mineral particles with a coating
composition including an infrared-reflective pigment. Color is
provided by colored infrared pigment, light-interference platelet
pigment, or a metal oxide.
[0031] U.S. Patent App. Pub. No. 20050229519 to Colbert et al. is
directed to coating and jointing material systems for wall
construction. The coating is applied to drywall elements prior to
installation and is compatible with the jointing materials such
that a substantially homogeneous surface may be obtained after the
drywall elements are assembled with jointing material and the
jointing material is dried. Methods for the construction of
interior walls and interior construction systems are provided.
[0032] 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, a joint strip, method of forming a wall using
the joint strip, and wall made therefrom, a structural product, an
aqueous latex caulking composition, a flexible setting joint
compound and method for making flexible joints, a high solids, low
shrinkage coating, a drywall coating composition, a water-based
marker material, a coating for wallboards, a textured exterior
surface treatment, a coating composition capable of forming a thick
coating film, prepaints and methods of preparing paints from the
prepaints, base coat stucco mortars for coating and finishing
interior and exterior walls of a building, a priming method for
uneven surface, a wallboard butt joint preparation, a method,
assembly and additional coat for the construction of interior
works, colored roofing granules with increased solar heat
reflectance, solar heat-reflective shingles, and process for
producing same, and a system using a drywall board and a jointing
compound, but does not teach an improved drywall joint construction
and method that both altogether eliminates the conventional weak,
chalky joint cement 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
[0033] The present invention teaches certain benefits in
construction and use which give rise to the objectives described
below.
[0034] Aspects of the present invention are 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, as is generally known in the art.
In the exemplary embodiment, the first and second lengthwise edges
of the drywall boards are non-tapered so as to form the crack
between the boards as a slit, wherein the joint finishing system is
configured as a flexible compound forming the flexible layer and
filling the slit so as to flush the joint finishing system with the
drywall boards. As such, 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.
[0035] 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.
[0036] Another objective is to provide such an invention capable of
reducing the amount of joint compound in a drywall joint.
[0037] A further objective is to provide such an invention capable
of eliminating the conventional joint cement from a drywall joint,
particularly at the center-line surface.
[0038] 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
[0039] The accompanying drawings illustrate the present invention.
In such drawings:
[0040] FIG. 1 is a perspective view of an exemplary embodiment of a
drywall joint of the present invention;
[0041] FIG. 2 is an enlarged cross-sectional view thereof taken
along line 2-2 of FIG. 1; and
[0042] FIG. 3 is a cross-sectional view of a prior art drywall
joint.
DETAILED DESCRIPTION OF THE INVENTION
[0043] The above described drawing figures illustrate the invention
in at least one exemplary embodiment, which is further defined in
detail in the following description.
[0044] Referring first to FIG. 1, 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 substantially adjacent the first drywall board
20 on a support structure 90 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. As a threshold matter, it is noted that in the
exemplary embodiment shown and described, no conventional joint
cement 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 cements 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 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 of the
conventional drywall joint is eliminated in the present invention
by eliminating the joint cement from the critical center-line
surface 80. Instead, a flexible layer 60, preferably of a flexible
compound such as caulk, forms the center-line surface 80.
Accordingly, 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.
[0045] Turning to FIG. 2, in the 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.
Specifically, in the exemplary embodiment the drywall boards 20, 30
are installed on support structure 90 such as framing studs or the
like as are now known or later developed in the art. Preferably, as
will be better appreciated from the following more detailed
description, the drywall boards 20, 30 are installed on the inside
or interior side of the support structure 90, or on the side of the
support structure 90 designed to be covered by a roof (not shown)
and enclosed away from the outside and the elements; i.e., on that
part of the building structure opposite the exterior. The drywall
boards 20, 30 are "non-tapered" or "non-recessed," such that the
abutting first and second lengthwise edges 22, 32 are substantially
perpendicular to the respective first and second planar surfaces
24, 34 and the crack 40 between the abutting boards 20, 30 is
configured as an outwardly-opening slit. The joint finishing system
50 comprises a flexible compound 52 defining the flexible layer 60
(FIG. 1) and filling the crack 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, a number of flexible compounds now known or
later developed will suffice. Preferably, in any such flexible
compound, any polymers or the like included in the formulation,
such as the 3M.RTM. glass bubbles, will have a glass transition
temperature (T.sub.g) that is greater than about -25.degree. C.,
rendering the resulting flexible compound relatively sandable and
finishable. 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, while the structural integrity of the
finished joint is yet improved. Again, the exemplary embodiment
shown in FIGS. 1 and 2 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 cement, so as to produce a joint construction 10 that is
stronger, more crack-resistant and more attractive. 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 a
flexible compound 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.
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 flexible compound 52 that shrinks
relatively less when setting.
[0046] Samples both of the exemplary drywall joint construction of
the present invention shown in FIGS. 1 and 2 and of the
conventional drywall joint construction shown in FIG. 3 were
evaluated for crack-resistance under the test explained below. The
conventional joint construction 110, again as shown in FIG. 3,
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 or more topping coats are required to flush the
joint, further weakening and adding more labor and material costs
to the conventional drywall joint.
[0047] 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 exemplary joint construction 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. 3) failed, or a crack was observed on the joint, at between
4.5 and 5.0 mm. Comparatively, in the exemplary joint construction
10 of the present invention (FIG. 2), no crack was seen until the
joint was flexed to between 210.0 and 220.0 mm from its unflexed
starting position, indicating that eliminating the joint cement by
replacing the conventional tapered drywall boards 120, 130 (FIG. 3)
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.
Thus, as in the exemplary joint construction 10 wherein no joint
cement is used at all (FIGS. 1 and 2), it is clear from this
testing that ridding the joint construction 10 of joint cement
altogether and instead comprising the joint of relatively more
board material, so as to reduce cost by requiring less filler
material in the joint, and of a flexible compound in filling the
crack between the boards and smoothing or flushing the surface,
produces the relatively 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
construction 10 of the present invention relative to a conventional
drywall joint 110. The testing proves that in the exemplary
embodiment of the present invention wherein the joint cement is not
only eliminated from the center-line surface of the joint, but also
from the entire joint, significant improvements in crack-resistance
over the conventional prior art drywall joint 110 were
achieved.
[0048] It follows that by removing the conventional joint cement
from the center-line surface 80 of the drywall joint construction
10 according to aspects of the present invention, a stronger, more
crack-resistant joint is achieved. Generally, drywall board is 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 joint construction, and particularly the center-line surface of
the joint, so as to produce an improved, stronger and more
crack-resistant drywall joint construction.
[0049] Moreover, the problem of surface cracking, which makes a
drywall joint unsightly and costly to repair, is effectively
eliminated by the joint construction 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 construction 10 of the present
invention is stronger and greatly reduces the risk of such surface
cracking by entirely removing the joint cement from the center-line
surface 80. Further, as is known in the art, the conventional joint
cement 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 of the present invention eliminates this
problem as well, again, by entirely removing the absorptive joint
cement from the center-line surface 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 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
joint construction. In this way, the paint would be unlikely to
crack before the joint ever would.
[0050] Beyond these structural and aesthetic considerations, those
skilled in the art will appreciate that the joint construction 10
of the present invention also provides economic benefits over the
conventional drywall joint 110. As seen, when non-tapered drywall
boards 20, 30 are employed, the space 40 to be filled in is
reduced, thereby reducing the materials required and, accordingly,
the labor needed to install the materials. In the exemplary joint
construction 10, the elimination of the drywall tape and drywall
joint cement altogether provides even further savings in terms of
both materials and labor.
[0051] Those skilled in the art will appreciate that there are a
number of reasons why even available flexible compounds and
non-recessed or non-tapered drywall boards known in the art have
heretofore not been combined or employed as taught herein to arrive
at an improved, joint cement-free drywall joint construction and
methodology. First, regarding prior art flexible joint systems such
as that disclosed in U.S. Pat. No. 6,884,830 to Hornaman, there is
a specific call-out that the compounds include an emulsion polymer
having a glass transition temperature (T.sub.g) of "less than about
-40.degree. C.; preferably less than about -45.degree. C." However,
it will be appreciated that the use of such emulsion polymers
renders the resulting compound relatively gummy and so difficult to
sand and finish as needed. As such, the use of such a compound in
forming a flexible drywall joint system has not gained commercial
acceptance. Moreover, it will be further appreciated that in the
Hornaman system there is called for a relatively more expensive
compound material, as compared with conventional joint cements and
even alternative flexible compound formulations, without any
decrease in the amount of material, as the use of non-recessed
drywall boards is not suggested, resulting in an increase in total
material cost (i.e., the Hornaman system essentially entails the
same volume of material as used in a prior art joint at a higher
material cost per unit volume). This aspect has likely further led
to non-acceptance of the Hornaman system in the field. Regarding
the use of non-recessed or non-tapered boards, current industry
thinking about the suggested applications for such, in view of the
general and pervasive industry teachings of preparing a drywall
joint as shown in FIG. 3, further teaches away from the present
invention. Specifically, it is well known in the industry to employ
non-recessed drywall boards only in three scenarios: (1) as backing
board for paneling or the like; (2) in interior drywall
applications where the finishing step will entail wallpaper, very
heavy texture, or the like and, expressly, not conventional paint;
or (3) in exterior applications. Thus, currently, the use of
non-recessed or non-tapered drywall boards has been taught away
from for conventional interior drywall applications wherein a
typical texture and surface paint are anticipated being applied
over the outside surfaces of the drywall boards. And those skilled
in the art will appreciate the reason for such teaching: heretofore
there has not been shown or taught in the art a system as in the
present invention whereby non-recessed drywall boards can be
employed in an interior joint without a bulge or hump at the
center-line surface of the joint that results in shadows or the
appearance of different color tones, which is a type of flashing or
photographing. That is, the use of non-recessed drywall boards,
though reducing the total amount of material needed to finish the
joint, under current joint finishing techniques yet results in a
so-called "humped joint" by virtue of the top coat of joint cement
and/or the drywall tape over the joint and so is not practiced.
Again, those skilled in the art will appreciate that such joint
cement and tape are eliminated in the joint construction and method
of the present invention, thereby enabling or facilitating the use
of non-recessed drywall boards even in conventional interior
drywall applications in conjunction with the present invention.
[0052] To sum up regarding the features and advantages of the
improved drywall joint construction and method of the present
invention, it will be appreciated that tremendous cost savings are
achieved in the form of less material by volume and less labor.
Specifically, material costs are greatly reduced in the present
system due to only filling a relatively small crack between
abutting, non-recessed drywall boards rather than a larger space
between recessed or tapered drywall boards as in the current
industry practice. Moreover, in the prior art, to fill such a
relatively large space often multiple coats are required to flush
the joint, leading to increased labor costs, both for each
application, as well as relatedly due to the longer dry times for
each coat and the delays between each. By comparison, the
application as in the present invention of a flexible, relatively
non-shrinking compound in a crack between non-recessed drywall
boards allows a single coat to effectively flush the joint, greatly
reducing the labor costs associated with the drywall finishing
step. It will be particularly appreciated that even prior art
flexible joint systems as disclosed, for example, by Homaman,
simply do not provide the same cost savings and advantages as the
joint construction and method of the present invention, in that
Hornaman involves a relatively higher cost material per unit
volume, making it more expensive at the outset and further more
expensive in that more material by volume is required as compared
to the present system. Thus, those skilled in the art will
appreciate that the present joint cement-free drywall joint
construction and method greatly improves the art of interior
drywall installation and finishing by tremendously reducing
material and labor costs. With these kinds of advantages, clearly
such a system would be known and used in the art were it obvious.
But the art has not employed such a system for the reasons
described, but has instead actually taught away from the use of
non-recessed drywall boards for most interior drywall applications,
whereby the system and method of present invention has solved a
problem not heretofore solved and so has satisfied a long felt and
as yet unmet need of reducing material and labor costs in the
widespread general art of interior construction using drywall or
gypsum boards.
[0053] Therefore, the present invention of an improved drywall
joint construction and method both altogether eliminates the
conventional weak, chalky joint cement 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 one exemplary embodiment, 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.
* * * * *