Note: Descriptions are shown in the official language in which they were submitted.
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DRYWALL CORNER FINISHING DEVICE
Background of the invention
1. Field of the Invention. This invention relates
to finishing interior walls. In particular, this
invention relates to finishing the edges at
intersections where two walls meet.
2. Statement of the Problem. Drywall panels are
widely used in the construction industry for forming
the interior walls and ceilings of rooms. Drywall
panels are made of a gypsum or reinforced gypsum core
covered with paper. Drywall panels have the
advantages of being easy to cut to desired sizes and
to attach to assorted types of framing. However, it
is very difficult to cut drywall panels so that the
edges are perfectly straight and smooth and can meet
to form a perfectly straight corner, which is
aesthetically to be desired. In addition, when the
drywall panels are cut to the desired sizes, the
edges of the panels are left exposed. This exposed
gypsum core is soft and tends to crumble unless the
severed edges are somehow protected. This is
especially important at outside wall corners.
When walls and ceilings are built of framing
materials such as wood, the inside and outside
corners thereby formed are seldom perfectly straight.
Small variations in the sizes of the wood framing
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members, warping of the wood, and inconsistent
building practices lead to imperfectly straight
corners where walls and ceilings meet, and where
walls end at doorways and passageways. When drywall
panels are then attached to the crooked framing
materials, their intersections will also be crooked.
An assortment of devices have been used to
provide a smooth and durable finish for the
intersections where two pieces of drywall abut to
form an inside or outside corner. Among the
conventional devices used are drywall tape and metal
corner beads. Conventional drywall tape is provided
in narrow, elongated ribbons or strips of porous
paper wound into rolls. The paper is sometimes
perforated to increase moisture penetration and to
prevent air bubbles from being entrapped behind the
tape. The drywall tape is first applied to joints and
edges of abutting drywall panels and is then covered
with wet plaster, sometimes called "mud." The plaster
is feathered and smoothed along the edges of the tape
to conceal the demarcations between the tape edges
and the drywall panels to which the tape is applied.
When the wet plaster has dried, the tape and drywall
can be painted or otherwise covered with a suitable
wall covering.
A great deal of skill is needed to apply the
plaster to both sides of an inside corner such that
a perfectly straight intersection is achieved. Also,
to correct the crookedness resulting from the warped
framing members and inconsistent building practices
described above, often several coats of plaster must
be applied, with an entire day of drying time needed
between each coat. Even then, a perfectly straight
corner seldom results. It is also likely that, unless
in the most highly skilled hands, the plaster trowel
T, .
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will mar the first side of the plaster while the
second side is being applied. Once the plaster has
been applied and dried, it must be sanded to an
appropriate finish to provide a surface suitable for
the application of paint or wallpaper.
Coffered and vaulted ceilings have recently
become very popular among homebuilders and buyers.
Often the peak of such ceilings will form an acute
angle. It is difficult to fit a conventional plaster
trowel into such angles.
Because drywall tape is formed of paper, it is
quite flexible and will conform to various surface
configurations of the edges of intersecting panels of
drywall. When conventional drywall tape is used at
the outside corners of walls, the flexibility of the
tape often results in a corner demarcation that is
irregular, since the tape conforms to irregularities
in the exposed, severed edges of the drywall panels.
The tape is also fragile and does not stand up well
to the constant physical abuse suffered by outside
corners. As a consequence, conventional drywall tape
cannot be used at exposed outside corners.
To finish outside corners in building
construction, therefore, metal corner beads are often
used. Conventional metal beads are configured in an
L-shaped or angle-shaped cross section and are
typically fabricated from elongated perforated strips
of metal, such as galvanized steel, permanently
deformed with a lengthwise 90-degree bend to form
elongated angles. The metal beading is typically
positioned at the intersections of adjacent drywall
panels that meet at right angles to form an outside
corner within a room. The sections of metal beading
are nailed in place through the drywall panels to
wooden supporting structural members located behind
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the drywall panels. Wet plaster is then smoothed into
place to cover the metal flanges or leg members of
the metal beading, and the edges of the plaster are
smoothed and feathered to attempt to conceal the
metal edges.
While the rigidity of the metal beading does
allow an outside corner of an inside building wall to
be finished with a sharp, straight edge, which is
aesthetically pleasing, the use of metal beading
involves some significant problems. Over time, the
metal corner bead will rust, thereby producing rust
stains that are clearly visible on the surfaces of
the walls at the corner. It is not always possible to
completely cover the edges of the metal flanges or
the nail heads used to attach the metal corner bead
to the drywall panel, detracting from the desired
smooth appearance of the wall. Cracks often develop
in the overlying plaster at the outer edges of the
flanges. To prevent this from happening, often two or
three coats of plaster are applied, with prior coats
allowed to dry and harden, which may take as long as
24 hours, before a subsequent coat is applied. When
the corners are crooked or jagged due to problems
with the underlying framing, metal beads do not cover
enough surface area or have enough flexibility to
correct the inequalities that exist. Another problem
is inherent in the fact that the malleable metal from
which the metal beads are made has a very poor memory
and is subject to being dented or wrinkled, after
which it is difficult to straighten it to produce a
smooth finish. Because of the rough handling to which
most of the material at a work site is subjected, it
is not uncommon for the strips to be wrinkled,
dented, and perhaps twisted, thus rendering them
either unusable, or usable only to produce an
r. .
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inferior end result. In addition, the metal strips
are used in large quantities in construction and can
add up to considerable cost.
A number of corner finishing devices have been
developed to address the above-described problems.
Among these devices are the following:
Inventor Patent No. Date
Swanson 3,444,657 May 20, 1969
Baker 3,989,397 Nov. 2, 1976
Ellingson 4,012,878 Mar. 22, 1977
Lamb 4,313,991 Feb. 2, 1982
Schaafsma 4,315,390 Feb. 16, 1982
Weinar 4,553,363 Nov. 19, 1985
Schneller 4,624,087 Nov. 25, 1986
Bernard 4,719,732 Jan. 19, 1988
Tucker 4,863,774 Sep. 5, 1989
Conboy 5,037,686 Aug. 6, 1991
Tucker 5,045,374 Sep. 3, 1991
Weldy 5,086,598 Feb. 11, 1992
Ritchie et al. 5,131,198 Jul. 21, 1992
Swanson and Lamb describe plastic joint strips
that can be reversibly bent to be adhesively secured
to both inside and outside corners.
Baker shows an outside corner connector for
waterbed pedestals in which the panels forming the
pedestal are inserted into the connector.
Ellingson provides a double-layer wall member
guard structure for outside corners made of a
resilient material.
Schaafsma describes two types of wallboard
corners, one for inside corners that is held in place
by putty and another for outside corners that is held
in place by the drywall panels themselves. The former
is disadvantaged by the fact that it is held on only
by putty; if the putty does not adhere well to the
drywall, the corner will become loose. The outside
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corner must be placed under the drywall panels,
involving considerable bending or, if placed on the
corner before the panels, a certain amount of extra
effort to hold the corner in place while the panels
are being nailed over it. Both corners use tape to
provide a smooth top finish that can be blended in
with the drywall finish by applying plaster and
sanding.
Weinar provides a plastic or metal T-shaped
corner construction in which the post of the T sits
between two abutting pieces of drywall and the cross
bar lies atop the drywall panels. Part of the paper
covering from one panel is wrapped around the cross
bar to provide a finished appearance, leaving a ridge
down one side of the corner. This corner construction
can only be used on outside corners.
Schneller describes yet another type of metal
outside corner bead in which an additional flange
extends over the edge of the drywall board forming
the outside corner. Ridges are left on both sides of
the corner, and this corner bead can only be used on
outside corners.
Bernard presents a plastic L-shaped outside
corner cover that uses heat-shrinkable plastic tape
along the arms both as a method of attachment and as
a method of providing a smooth junction between the
cover and the drywall. This cover can be used for
outside corners having a variety of angles.
Tucker provides a paper drywall ribbon having a
centrally located plastic bead extending
longitudinally along the ribbon. Plaster is used to
attach the ribbon to the drywall. This plastic bead
is designed to be used with outside corners only.
Conboy describes a plastic drywall tape that can
be used on both inside and outside corners. Again,
7'
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this plastic tape is held on the corner with plaster,
and plaster is used to provide a finished appearance.
Tucker describes a stiff plastic strip with a
curved center section and two flanges that is
attached to outside or inside corners with adhesive.
The flanges are then covered with paper tape strips
and plaster.
Weldy provides a wall edging system for both
inside and outside corners that comprises a plastic
strip having an arcuate center portion to which are
attached two flanges at right angles. The strip is
attached to the drywall with nails. Plaster is then
smoothed over the strip to finish the edges. The side
of the strip facing out toward the room can be
finished with primer.
Ritchie et al. describe a corner bead for
outside corners that has a metal core and that is
completely covered by paper. This bead has a rounded
nose and side flanges. The paper covering is further
coated with a reinforcing emulsion. The corner bead
is nailed to the drywall, and plaster is used to hide
the edges.
A need exists for a drywall corner finishing
device that can be used on both outside and inside
corners having various angles and that provides a
primed surface for either orientation. A further need
exists for a drywall corner finishing device that can
be used to cover juxtaposed outside corners, such as
are found at the edges of interior doorways or other
openings of various dimensions, for example,
passthroughs from one room to another. Because of the
crooked corners that result from warped building
materials and inconsistent building practices, a need
exists for a corner finishing device that will
provide a perfectly straight corner without the use
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of multiple coats of plaster. A finishing device is
also needed that will simplify installation of
drywall in acutely angled inside corners and minimize
the need to use plaster. None of the above-described
drywall corners fulfills these needs.
3. Solution to the Problem. The drywall corner
finishing device described herein can be used for
both inside and outside corners having various
angles. Builders will not have to order two or more
versions to cover different types of corners. The
drywall corner finishing device described herein can
also be used to cover two adjacent outside corners
without requiring the use of a narrow strip of
drywall panel between the corners and two finishing
devices, one for each outside corner. A layer of
primer or laminate covers the side of the drywall
corner finishing device of the present invention that
faces into the room. Because of this primer or
laminate layer, plaster need only be used on the
outside edges of the corner finishing device where it
abuts the drywall. The drywall corner finishing
device described herein has a width generally equal
to that of the drywall panels, so that little plaster
is needed to fill in the area where the drywall
panels meet the finishing device. The drywall corner
finishing device of the present invention is capable
of hiding crooked, uneven corners no matter how
irregular the deviations may be. The present drywall
corner finishing device is nailed directly to the
framing members of the wall, thereby providing
stability.
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Summary of the Invention
A finishing device used to form a corner
between two panels of drywall has a flexible joint
extending along a predetermined axis. Two wings are
connected to and extend outwardly in a diverging
relation from the flexible joint to form a corner
having an adjustable angle. Each wing has a front
surface, a rear surface, and an edge distal from the
flexible joint. This edge abuts one of the drywall
panels and has a thickness approximately equal to the
thickness of the drywall panel. A layer of primer or
adhesive laminate is applied to the front surface of
the wings so that paint or wallpaper or other
wallcoverings can bond to the front surface. The
finishing device is capable of forming both inside
and outside corners. To form inside corners, the
finishing device bends along the flexible joint. To
form outside corners, strips parallel to the flexible
joint are removed from the rear surface of the wings
and the finishing device is folded along the openings
thus created.
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Brief Description of the Drawings
The present invention can be more readily
understood in conjunction with the accompanying
drawings, in which:
FIG. 1 is a partial perspective view of the
drywall corner finishing device in accordance with
the present invention;
FIG. 2 shows a cross-sectional view of the
drywall corner finishing device in accordance with
the present invention;
FIG. 3 is a detailed cross-sectional view taken
from the outlined section of FIG. 2 showing the front
surface of the drywall corner finishing device in
accordance with the present invention covered with a
layer of primer;
FIG. 4 shows a detailed cross-sectional view
taken from the outlined section of FIG. 2 showing the
front surface of a second embodiment of the drywall
corner finishing device in accordance with the
present invention covered with a layer of adhesive
laminate;
FIG. 5 shows a cross-sectional view of the
drywall corner finishing device in accordance with
the present invention bent to fit inside corners;
FIG. 6 is a detailed cross-sectional view of the
center joint of the drywall corner finishing device
as shown in FIG. 2;
FIG. 7 shows a detailed cross-sectional view of
the center joint of the drywall corner finishing
device as shown in FIG. 5;
FIG. 8 shows a cross-sectional view of the
drywall corner finishing device in accordance with
the present invention applied to an inside corner
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between a wall and a ceiling;
FIG. 9 is a cross-sectional view of the drywall
corner finishing device in accordance with the
present invention applied to an inside corner formed
at the top of a ceiling;
FIG. 10 shows a cross-sectional view of the
drywall corner finishing device in accordance with
the present invention applied around two outside
corners;
FIG. 11 is a cross-sectional view of the drywall
corner finishing device in accordance with the
present invention applied around two outside corners
separated by a greater distance than the outside
corners shown in FIG. 10;
FIG. 12(a) shows a detailed cross-sectional view
of the removable strip of the drywall corner
finishing device in accordance with the present
invention;
FIG. 12(b) is a detailed cross-sectional view
showing the removal of the removable strip of FIG.
12 (a) ;
FIG. 12(c) is a detailed cross-sectional view
showing how the drywall corner finishing device is
folded after the removal of the removable strip of
FIG. 12 (a) ; and
FIG. 13 is a cross-sectional view of the drywall
corner finishing device in accordance with the
present invention showing the application of plaster
to the joint.
FIG. 14 is a cross-sectional view of an
alternative embodiment of the drywall corner
finishing device.
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Detailed Description
Turning to FIG. 1, the left 102 and right 104
wings of the drywall corner finishing strip are
attached to a flexible center joint 100 and extend
outwardly therefrom to a distal edge 110. The wings
102, 104 have a front surface 106 and a rear surface
108. The front surface 106 and rear surface 108
extend outwardly beyond the distal edge 110 of the
wings 102, 104 to cover the distal edge 110. When the
drywall corner finishing device covers either an
inside corner or an outside corner, the rear surface
108 of the device is juxtaposed to the framing of an
interior wall while the front surface 106 faces out
into the room, contiguous with the surface of the
drywall panels forming the wall. The front surface
106 may be covered with a layer of primer 300 as
shown in FIG. 3 so that any paint or wallcovering
that is eventually used to decorate the wall will
adhere easily. Alternatively, the front surface 106
may have an adhesive laminate 400 attached to it as
shown in FIG. 4.
The structure of the drywall corner finishing
device is more clearly seen in FIG. 2. The flexible
center joint 100 is preferably arcuate, but it is to
be expressly understood that any joint shape, such as
V-shaped, U-shaped, C-shaped, etc., can be used that
allows the device to bend through a variety of angles
at the center joint 100. The center joint 100 extends
along an axis that extends linearly to form a corner
or edge.
A number of struts 206 separate the rear surface
108 of each wing 102, 104 from the front surface 106
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of each wing 102, 104. In the preferred embodiment
shown in FIGs. 1 and 2, the pattern of struts 206
provides stability to the structure of the corner
device and also allows the device to be folded around
outside corners, as discussed in more detail below.
It will be obvious to one skilled in the art that the
pattern of struts 206 shown in FIGs. 1 and 2 is not
the only pattern that will provide these features of
stability and folding and that other patterns would
be suitable and are to be included in the present
invention.
The edge 202 of the rear surface 108 extends
beyond the edge 200 of the front surface 106. The
distal portion 204 of the front surface 106 tapers
slightly toward the rear surface 108 so that, as
discussed in more detail below, the edge of a drywall
panel can be placed in the space 114 between the
front surface 106 and the rear surface 108 such that
the edge 202 of the rear surface 108 and the edge 200
of the front surface 106 are in close apposition to
the drywall panel. The rear surface 108 contains a
number of removable strips 208, 210 that are removed
when it is desired to fold the drywall corner
finishing device around outside corners, as discussed
in more detail below.
FIG. 8 illustrates the inside corner formed when
a vertical wall meets a coffered or cathedral
ceiling. FIG. 9 shows the inside corner formed at the
vault of such a ceiling. Depending on the design of
the building, these corners may have angles ranging
from less than 90 degrees to 180 degrees. When the
drywall corner finishing device is used to finish an
inside corner, the rear surface 108 is first placed
directly against the framing. The center joint 100
flexes from 180 degrees, shown in FIG. 6, to the
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appropriate angle needed to fit the angle made by the
corner, as shown by arrow 500 in FIG. 5 and arrow 700
in FIG. 7.
As an example, in FIG. 8, the finishing device
is attached to the wall framing 800 and ceiling
rafter 802 by use of nails 806. The finishing device
is made of plastic soft enough to permit the nails
806 to be driven through the flange 112 of the rear
surface 108 without the need for pre-formed holes. It
is to be expressly understood that other methods such
as the use of screws, bolts, adhesive, etc., will be
equally efficacious in attaching the finishing device
to the supporting members of the wall or ceiling. The
attachment location of the device and the positions
of the nails 806 can be varied to enable the device
to correct inequalities that may exist within the
framing and from one framing member 800 to the next.
If necessary, shims may be placed behind the device
before it is attached by nails 806. After the device
has been securely attached to the framing 800 and
rafter 802, the edges of the drywall panels 804 are
inserted into the spaces 114 between the front
surface 106 and rear surface 108, such that the edges
of the drywall panels 804 abut the distal edges 110
of the wings 102, 104. It can be seen in FIG. 8 that
the spaces 114 between front surface 106 and rear
surface 108 are just large enough to accommodate the
drywall panels 804 and that the front surface 106 and
rear surface 108 are closely juxtaposed to the
drywall panels 804. The drywall panels 804 thus hide
the nails 806. The drywall panels 804 are attached to
the framing 800 and rafter 802 in the usual fashion.
As FIG. 13 shows, plaster 1300 is then applied
to the tapered distal portion 204 of the front
surface 106 and the tapered edge of the drywall panel
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804 to hide the edge 200 and provide a smooth, level
surface. Because plaster 1300 is applied only to the
tapered portion 204 of the finishing device,
difficulties inherent in plastering within corners
are avoided. Such difficulties include, among others,
the difficulty in maneuvering a plaster trowel within
a corner, the skill needed to produce a perfectly
straight edge where the two sides of the corner meet,
and the need for several layers of plaster 1300 to
completely hide the joint between the finishing
device and the drywall or to correct the inequalities
resulting from mis-sized, mis-placed, or warped
framing members, with each layer requiring
considerable time to dry. Once plaster 1300 has been
applied, the surface of the wall can be finished by
painting, wallpapering, or any other method desired.
The primer 300 bonded to the front surface 106
enables paint or other wallcoverings to adhere to the
front surface 106 of the finishing device. In another
embodiment, a laminate 400 can be adhesively affixed
to the front surface 106 to provide a surface for
subsequent painting.
A second example of the use of the finishing
device for inside corners is shown in FIG. 9. Here,
the finishing device provides an inside corner
essentially as described above, except here the
corner is that formed by the vault of a coffered
ceiling. The device is attached to the rafters 900 by
driving nails 904 through the flanges 112. The
attachment location of the device and the positions
of the nails 904 can be varied to enable the device
to correct inequalities that may exist within the
rafters 900 and from one rafter 900 to the next. If
necessary, shims may be placed behind the device
before it is attached by nails 904. The edges of the
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drywall panels 902 are then inserted into the spaces
114 between the front surface 106 and rear surface
108. As above, these spaces 114 are just large enough
to accommodate the edges of the drywall panels 902,
so that the front surface 106 and rear surface 108
are in close apposition to the drywall panels 902.
The drywall panels 902 thus hide the nails 904. The
drywall panels 902 are attached to the rafters 900 in
the usual fashion. Plaster 1300 is then applied to
the tapered distal portion 204 of the front surface
106 and the edge of drywall panels 902 to provide an
even surface. Because of the primer 300 or laminate
400 covering the front surface 106, it is not
necessary to use plaster on the remainder of the
front surface 106, and the difficulties of plastering
within the tight angles formed by inner corners are
avoided. The surface of the wall is then painted or
otherwise finished as desired.
Often outside corners exist next to each other.
Two examples of such outside corners are shown in
FIGs. 10 and 11. Figure 10 illustrates outside
corners formed by 2-by-4 framing boards 1000, 1002,
and FIG. 11 shows outside corners formed by 2-by-6
framing boards 1100, 1102. The rear surface 108
contains at least two sets of removable strips 208,
210. It is to be expressly understood that the
removable strips 208, 210 can be located in any
convenient place on the rear surface 108 and that the
present invention is not limited to the locations of
the strips 208, 210 shown. Strips 208 are removed
when 2-by-4 boards 1000, 1002 are used, and strips
210 are removed when 2-by-6 boards 1100, 1102 are
used. Once the strips 208 or 210 are removed, the
front surface 106 can be bent around both outside
corners. This process is described below and shown in
T. ,
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FIGs. 12 (a) - 12 (c) .
A removable strip 208 is held by a number of
thin tags 1200 between the struts 206 parallel to the
rear surface 108. To remove a strip 208, one need
only break the thin tags 1200. The strip 208 is then
removed in the direction of the arrow 1202 and
discarded. The front surface 106 is then bent in the
direction of the arrow 1204 to form a corner that
will fit around one of the adjacent outside corners.
It is to be understood that a similar but mirror-
image process occurs with the second strip 208, so
that the front surface 106 can be bent to form a
second corner that will fit around the second of the
juxtaposed outside corners. The strips 210 are
removed in the same manner to permit the finishing
device to be bent around two outside corners that are
further apart.
Once the strips 208 or 210 are removed and the
front surface 106 is bent, the finishing device is
attached to the framing board 1000 or 1102 by use of
nails 1004 or 1104. The attachment location of the
device and the positions of the nails 1004, 1104 can
be varied to enable the device to correct
inaccuracies that may result from warped or mis-sized
framing boards 1000, 1002, 1100, 1102 or
inconsistencies in building practices. If necessary,
shims may be placed behind the device before it is
attached by nails 1004, 1104. The drywall panels
1006, 1106 are inserted as described above for inside
corners, and the joint between the finishing device
and the drywall panels 1006, 1106 is finished in the
same manner as described above and shown in FIG. 13
for inside corners.
FIG. 14 shows a cross-sectional view of an
alternative embodiment of the present invention.
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This embodiment provides only one set of removable
strips 210 located equidistant from the center joint
100. The number and complexity of the struts 206 has
also been reduced to simplify manufacture of the
device by plastic extrusion. The arrangement of the
distal struts 207 has also been changed for greater
support to the tapered end 204 of the front surface
of the device. If a portion of the rear flange 112
is drawn rearward to accommodate an uneven section in
a rafter, the distal strut 207 will tend to allow the
tapered front surface 204 of the device to maintain
a straight edge in spite of irregularities in the
underlying rafters. Assuming the device is molded
from some type of flexible plastic, the end strut 205
will deform as necessary to accommodate such
irregularies.
The above disclosure sets forth a number of
embodiments of the present invention. Other
arrangements or embodiments, not precisely set forth,
could be practiced under the teachings of the present
invention and as set forth in the following claims.
