Kick-proof doorjamb reinforcing means and assembly

A reinforcing plate for reinforcing a doorjamb to prevent break-ins and particularly kick-ins of the door by unauthorized persons is mounted in back of the doorjamb in the space between the jamb and the door frame. In order to install the reinforcing plate behind the doorjamb, the interior trim strip is removed from the door frame and the reinforcing plate is mounted behind the doorjamb, preferably by the use of shims to temporarily jam the plate between the doorjamb and the door frame. While the reinforcing plate is temporarily secured by a wedging means against the back of the door frame, holes are drilled in the door frame and through the reinforcing plate using appropriately-sized drill bits. Self-tapping threaded screws are then passed through the doorjamb and screwed tightly into the reinforcing plate the attach the plate to the doorjamb and reinforce the jamb. As an alternative, special fastenings are provided to fasten the striker plate to the reinforcing plate.

BACKGROUND OF THE INVENTION 
(1) Field of the Invention 
This invention relates to anti-burglary devices and more particularly to 
the provision in a convenient retrofitable form of a reinforcing means for 
the doorjambs of residences and the like. 
(2) Discussion of the Prior Art 
One of the prime methods of entering residences and other buildings by 
burglars and strong-arm men, not to say law enforcement personnel who wish 
to take the occupants by surprise, is a simple kick to the door near the 
bolt or latch. Since the striker plate into which the latch of the door 
slides is usually merely bolted to the doorjamb about a routed-out orifice 
in the doorjamb, a well placed kick will usually break the striker plate 
from the doorjamb fracturing the jamb in the process and allowing the door 
to fly open. This is as true with modern steel-cased doors as with older 
doors, since the striker plate is positioned invariably along the edge of 
the jamb with only a minimum of wood about the latch opening which the 
striker plate is supposed to reinforce. 
A great number of arrangements have been invented in the past for 
reinforcing the doorjamb in the striker plate area, many of which have 
been relatively effective, but none of which have achieved any substantial 
use due to impracticalities in their design and implementation. 
Among the arrangements that have been tried and found wanting due to 
impracticality, even though effective in reinforcing the door, are those 
disclosed in the following patents: 
U.S. Pat. No. 3,338,008 issued Aug. 29, 1967 to S. Sklar discloses a 
so-called knock-down door buck construction comprising a method of forming 
and installing a doorjamb and head piece. The arrangement is comprised of 
preformed pieces and includes metal clips which are attached to the frame 
of the door and incorporate flanges which extend outwardly into grooves in 
the trim strips on the side of the door frame. 
U.S. Pat. No. 3,767,245 issued Oct. 23, 1973 to John N. Keefe discloses a 
reinforced striker plate for a doorjamb. The striker plate of Keefe has an 
elongated extension along one side which may be mounted flush against the 
doorjamb under the door's stop striping. The arrangement provides 
essentially a reinforced striker plate. 
U.S. Pat. No. 3,815,945 issued Jun. 11, 1974 to E. R. Lamphere discloses a 
combined reinforcing plate and striker plate in the form of an expanded or 
reinforced striker plate having a shape arranged to extend over a fairly 
large portion of a doorjamb and an integral door stop upon the doorjamb. 
The expanded combination striker plate and reinforcing plate are held 
against the doorjamb by means of screws extending completely through the 
doorjamb and into the studding of the door frame. The reinforced striker 
plate and reinforcing plate preferably has small flanges along the edges 
to aid in engaging with the doorjamb. 
U.S. Pat. No. 3,918,207 issued Nov. 11, 1975 to P. Aliotta discloses a 
doorjamb reinforcing arrangement in which the jamb is backed by a metal 
plate which may extend essentially across the entire rear of the jamb and, 
if necessary, from one end to the other of the jamb. The metal plate is 
provided with spaced fastening holes and may be fastened either by screws 
or bolt-type fastenings which pass either from the rear of the plate 
through the pre-drilled holes in the plate into the back of the doorjamb 
or alternatively by bolts which pass from the front of the doorjamb 
through the jamb into and through the reinforcing plate on the rear. A 
jamb reinforcing plate is also provided with a flange along one side to 
reinforce the side of the jamb closest to the one side to reinforce the 
side of the jamb closest to the striker plate hole. Either the side of the 
jamb or the back of the trim strips must be routed out on the side where 
the flange is provided in order to provide a tight fitting connection. The 
practicality of the Aliotta plate is consequently severely compromised by 
the necessity for performing operations which are inconvenient and 
difficult to carry out in the field. 
U.S. Pat. No. 3,963,269 issued Jun. 15, 1976 to S. R. Rosenberg discloses a 
door strengthening arrangement including a metal casing which passes 
around the outer portion of a doorjamb, including a door stop arrangement. 
A special slotted reinforcing plate is mounted directly upon the door and 
when the door is closed, an extension from the striker plate passes 
through the slotted member on the door and aids in preventing the door and 
the doorjamb from being sprung apart by means of a crowbar or the like. 
One small section of the expanded striker plate is designed to extend 
around the front of the doorjamb and interlock with the back of the jamb. 
U.S. Pat. No. 3,967,845 issued Jul. 6, 1976 to B. C. Governale discloses 
the use of an expanded reinforcing plate positioned over the latch orifice 
to basically reinforce the front of the doorjamb about the latch orifice. 
A conventional striker plate is mounted directly over the reinforcing 
plate and substantially obscures the reinforcing plate from outside view. 
The reinforcing plate is therefore substantially concealed from view both 
by being under the conventional striker plate and also having its expanded 
section on one side hidden under the weather stripping which normally is 
provided along the jamb adjacent to the doorstop. 
U.S. Pat. No. 4,057,275 issued Nov. 8, 1977 to L. J. La Beaud discloses an 
elongated metal reinforcing plate fastened to the back of a wooden 
doorjamb to reinforce the doorjamb opposite to a conventional striker 
plate. The La Beaud plate has angled teeth which extend into the doorjamb 
from the back. A flange is provided on one side of the La Beaud 
reinforcing plate forming an angled lip extending along one side of the 
plate. This lip is arranged to catch behind the latch of the door and 
extends on both of the latch sides in an opening or slot in the doorjamb. 
U.S. Pat. No. 4,174,862 issued Nov. 20, 1979 to C. F. Shane discloses a 
door frame reinforcing plate in which a metal plate is provided on the 
back of the doorjamb. The lock bolt extends completely through the jamb 
and through an orifice in the metal plate. A bent-over section of the 
reinforcing plate also is extended over the outside end of the doorjamb. 
In a more preferred embodiment, furthermore, an additional extension of 
the metal plate is bent around the back of the two by fours (2".times.4"s) 
of the door frame so that the metal reinforcing plate takes the form of a 
U-shaped plate which almost completely surrounds the timbers of the door 
frame. 
U.S. Pat. No. 4,195,870 issued Apr. 1, 1980 to J. Percoco discloses a 
striker plate reinforcing arrangement. There are several embodiments of 
the Percoco device including the use of a block-type striker plate 
providing a heavier section into which the latch bolt extends. Such 
block-type striker plate is attached in various ways to other portions of 
the door. 
U.S. Pat. No. 4,295,299 issued Oct. 20, 1981 to D. M. Nelson discloses a 
J-shaped reinforcing plate having the major arm on the back of the 
doorjamb and the minor arm on the front of the doorjamb with a connecting 
web extending along the outer end of the doorjamb. The reinforcing plate 
is applied to the doorjamb by removing the outer trim and apparently a 
groove is also provided in the front of the doorjamb also to accommodate 
the end of the minor arm of the plate section. No space is shown behind 
the doorjamb into which the rear portion of the reinforcing plate fits. 
The Nelson patent shows a fastening in the form of a nail passing from the 
front of the doorjamb through the doorjamb into and through the major arm 
of the reinforcing plate extending along the back of the jamb. It is not 
quite clear how the nail is forced into the plate. Nelson does constitute 
a broad disclosure of having a reinforcing plate extending along the rear 
of a doorjamb and a fastening extending from the front of the doorjamb 
through the plate to hold it in place against one of the framing two by 
fours (2".times.4"s) of the door frame. 
U.S. Pat. No. 4,383,709 issued May 17, 1983 to T. O. Ronan discloses a 
striker plate which in one embodiment completely ensheaths a section of 
the outer portion of a doorjamb. The main thrust of the Ronan patent is to 
provide a blocking plate adjacent to the lock to prevent tools from being 
inserted from the outside to spring the bolt. 
U.S. Pat. No. 4,416,087 issued Nov. 22, 1983 to P. K. Ghatak discloses a 
reinforcing plate mounted along the edge of a doorjamb to reinforce such 
jamb against fracture by a sharp kick or the like. Long bolts are shown 
extending from the heavy reinforcing plate longitudinally across the 
doorjamb into a bolt or nut opening near the opposite side of the 
doorjamb. Ghatak indicates his reinforcing method very effectively 
reinforces the doorjamb against the type of force which is usually used to 
kick open a door. 
U.S. Pat. No. 4,684,160 issued Aug. 4, 1987 to G. J. Nelson discloses a 
reinforcing plate for use on the back of a doorjamb in conjunction with 
the usual striker plate on the front of the doorjamb. The reinforcing 
plate is designed to be attached to the frame members of the doorjamb and 
has the further elaboration of having a reinforced chute or column passing 
through the doorjamb in the vicinity of the striker plate which reinforced 
chute or column the latch bolt enters to provide a secure locking 
arrangement. 
U.S. Pat. No. 4,717,185 issued Jan. 5, 1988 to R. A. Hartley discloses a 
combined striker plate and reinforcing plate which has side extensions 
extending inwardly along the sides of the two by four (2".times.4") 
framing members of the door frame. A forward extension from the striker 
plate surface also serves to reinforce the door stop of the door. Hartley 
specifically discloses that his arrangement is designed for new 
construction where the combined striker plate and reinforcing plate can be 
conveniently mounted on the original door frame. 
U.S. Pat. No. 4,770,452 issued Sep. 13, 1988 to R. W. Petree discloses a 
reinforcement plate inserted into a groove in the doorjamb to reinforce 
such doorjamb. The plate is secured also directly to the framing members 
by a long threaded connector. The reinforcing plate, which is inset into a 
routed out portion of the doorjamb, is fairly long so it reinforces a 
large portion of the doorjamb. An ordinary striker plate is normally used 
on the outside of the doorjamb. Petree makes a point of the fact that his 
reinforcing plate can be retrofitted into existing structures. Petree 
states that in his invention only the outer doorjamb is removed and the 
security plate is installed into a groove routed out in the doorjamb 
without direct engagement or modification of any of the underlying support 
studs in the wall about the door frame. 
U.S. Pat. No. 4,802,701 issued Feb. 7, 1989 to G. S. Mazie discloses a 
reinforcement plate for a lock which plate is installed behind the 
doorjamb. The reinforcing plate has a groove in it which receives a right 
angle bend on the doorjamb through the groove in the reinforcing plate and 
into a groove formed in the underlying frame of the door. Various screw 
fastenings may be used to mount the reinforcing plate directly upon the 
two by four (2".times.4") frame members of the door and a transverse screw 
member may be used to secure the right angled bent portion of the special 
striker plate in the groove. 
U.S. Pat. No. 4,854,621 issued Aug. 8, 1989 to R. L. Baldwin discloses a 
combined striker plate and reinforcing plate arrangement in which an 
extended portion of the striker plate is bent into a "U" shape which 
passes about the doorjamb to basically reinforce the jamb itself. The 
arrangement is somewhat analogous to the Shane arrangement in which a 
plate passes across the back of the doorjamb and then is bent around the 
beams in the door frame rather than about the doorjamb itself. Baldwin has 
a further preferred arrangement comprising an angled plate arranged to be 
secured to the door frame itself and extend along the edge of the door 
frame over the plate extending around the back of the jamb. The jamb 
plate, in this way, is held securely to the door frame. Baldwin discloses 
he can also use the U-shaped striker plate alone without the additional 
security of the angled plate which normally holds the striker plate to the 
door frame members themselves. In such simplified embodiment, as noted 
above, the arrangement would appear to be primarily a reinforcement of the 
doorjamb. Baldwin discloses his arrangement is relatively easy to install. 
In new buildings, the U-shaped striker member and the angled tie plate can 
be positioned prior to attachment of the wooden trim or molding in the 
doorway. In existing doors, on the other hand, the existing striker plate 
is first removed and the door trim or molding is removed so that the 
striker plate member can be placed around the inner edge of the doorjamb 
while the tie plate member is hooked over the outside of the wall next to 
the doorway so that one leg extends between the door frame and the arm of 
the striker plate. The door trim molding is then secured to the doorway by 
screws to anchor the two members together. 
U.S. Pat. No. 4,865,370 issued Sep. 12, 1989 to C. E. Francis discloses a 
boxed-in reinforced striker plate orifice. The reinforced boxing is 
attached to an anchor plate "preferably secured by long screws extending 
through the jamb into the trimmer stud". The reinforced striker bolt 
receiving chamber, referred to as an "anchor pocket", extends from the 
anchor plate side of the doorjamb forming an orifice in the jamb into 
which the deadbolt is extended. It is said that forceful entry is 
prevented since the anchor plate strengthens the doorjamb, "thus giving a 
very strong structural combination which can resist a rather strong 
splitting force caused by an attempted forceable entry". Francis uses 
shims in FIG. 7 and in FIG. 9 to retain the anchor plates against the rear 
of the jamb, evidently while a screw is turned into and through the 
reinforcing plate. In FIG. 8, the reinforcing plate is shown with a series 
of orifices for allowing passage of the screws through the plate. 
U.S. Pat. No. 5,003,727 issued Apr. 2, 1991 to E. Watten discloses the use 
of a direct reinforcement of a striker plate by removing or mortising out 
a portion of the doorjamb under the striker plate and inserting into such 
portion a metal reinforcing element which may be a bent-over portion of a 
backing plate or a metal piece welded onto a backing plate which extends 
along the rear portion of the doorjamb. The reinforcing or backing plate 
on the back of the doorjamb is shown in FIGS. 4a and 4b as being secured 
to the jamb either by helical screws extending from the rear into the back 
of the jamb or from the front of the jamb through the reinforcing plate 
into the door opening. 
While there has been broad recognition, therefore, that some practical 
means for reinforcing doorjambs against fracture due to kicks and the like 
intended to either spring open the door or to fracture the doorjamb and 
allow the door to swing open, would be desirable, such arrangements as 
have been tried have not proved to be really practical and consequently 
have been used little, if at all. In particular, the prior art has not 
embodied a reinforcing arrangement which can be easily mounted by 
relatively unskilled labor on either old installations of doors or new 
installations of doors and has not been sufficiently practical to 
encourage those in the art to provide the reinforcing means as a standard 
in house construction. Nor has there been an arrangement or method that 
could be retrofitted to existing door assemblies by relatively unskilled 
labor such as the usual homeowner. 
There has been a clear need, therefore, for a simple, practical method and 
means for reinforcing the doorjambs of both existing buildings and new 
buildings to prevent the door from being broken open relatively easily by 
exposure to sharp blows such as may be delivered by a swift kick or other 
forceful entry-inducing force. 
BRIEF DESCRIPTION OF THE INVENTION 
The present invention provides a reinforcing kit for reinforcing doorjambs 
to prevent their fracture around the striker plate by the application of a 
sharp force such as may be delivered by a kick or other forceful blow. The 
arrangement of the invention provides a reinforcing plate as part of a kit 
together with threaded-type, self-tapping fastenings and a drill bit 
arranged to be used with such fastenings to provide orifices through the 
doorjamb and directly into the reinforcing plate, which has been installed 
at the rear of the doorjamb. The door reinforcing plate is held in 
position during installation and to some extent subsequent thereto, by the 
use of a jamb-type or wedging support means which may comprise several 
triangular shims which temporarily jam the plate in position while it is 
being drilled. Self-tapping screws, or other self-tapping, threaded 
fasteners for passage into the drilled holes in the jamb and in the 
backing plate, are also provided. These self-tapping fasteners should also 
be provided with non-reversible or one-way heads. 
The invention also provides a method for securing a backing plate or 
reinforcing plate to a doorjamb. In a variation of the invention, a 
special base arrangement for attaching the striker plate of the door 
directly to the reinforcing plate through direct steel contact is provided 
by reason of cylindrical backing members which may be screwed into the 
backing plate with self-tapping screws and serve as a solid base upon 
which the striker plate may be screwed directly to the reinforcing plate. 
In most cases, however, if the self-tapping screws are used to pull the 
striker plate forcefully against the side of the doorjamb so that the wood 
of the doorjamb is force-fully compressed between the striker plate 
structure and the reinforcing plate structure, the wood of the doorjamb 
being compressed serves in itself as a composite structure having great 
strength which prevents the striker plate from being broken out from the 
doorjamb by a severe external force such as a sharp kick or the like due 
to the reinforcement arrangement. The specific aim of the invention is to 
provide a practical doorjamb reinforcing arrangement which can be used 
easily in the field, including the retrofitting of existing structures by 
relatively unskilled labor, including owners of the building itself as 
well as professional builders and the like, and such builder's carpenters 
and other less skilled workers. The final reinforced door assembly 
comprised of a reinforcement plate on the rear of the doorjamb pulled 
tightly against the jamb and attached firmly to the striker plate by 
threaded fasteners, of which at least the fasteners passing directly from 
the doorjamb into the reinforcing plate are self-tapped, threaded 
fasteners, provides a very strong arrangement or assembly which, even 
though simple and economical, successfully resists strong-arm-type 
breakage of the doorjamb and associated structures and particularly 
successfully resists sharp blows such as kicks and the like.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As reviewed above, there have been a number of devices and means suggested 
for the reinforcement of doorjambs and striker plate orifices in order to 
reinforce the locking of a door and particularly to prevent a door from 
being broken down by persons wishing unauthorized access to residences and 
other enclosures While some of the arrangements suggested in the prior art 
for strengthening doorjambs and other portions of the door frame have not 
been too effective, a number, in fact, have been quite effective in 
strengthening the door and preventing it from being sprung open with a 
sharp blow or kick. However, so far as the present inventor is aware, all 
of such prior devices have been difficult to apply and/or expensive to 
such a degree that few have ever been used extensively, if at all. In 
particular, the devices of the prior art have been largely impossible to 
conveniently retrofit into an existing door frame structure without major 
modifications. Also, such devices have not lent themselves to use even by 
builders, because the devices have either been so expensive that few 
builders have wished to provide them or so complicated to install that 
builders have not wished to become involved with them due to the 
relatively unskilled labor which is frequently used for such 
installation-type work. 
Homeowners, on the other hand, are usually relatively unsophisticated 
concerning the hidden portions of their homes and while home mechanics 
frequently have sufficient perseverance and time as well as the funds to 
install effective strengthening means for doorjambs and door frames and 
the like, their lack of knowledge concerning what lies behind the walls 
and facings of their home makes it relatively difficult to install most 
devices which require any modification at all to the structure and trim of 
their home. 
The present inventor has discovered and devised a new arrangement and 
method for strengthening the doorjamb of a door assembly which makes it 
very difficult to fracture the doorjamb as is usually necessary to kick 
down the door. The arrangement and method, furthermore, are simple, 
effective and easy to use both by relatively unskilled and unmotivated 
labor and interested, but relatively inexperienced and unknowledgeable 
homeowners and home handymen. Applicant provides for this purpose, a 
simple strengthening plate of fairly heavy gauge such as 16 gauge steel 
plate which is supplied beforehand only with lock bolt openings or the 
like, if necessary. Such plate is designed to be installed in the normal 
opening between a doorjamb and the door framing members, which opening is 
invariably provided in order to allow the door to be plumbed or matched to 
the opening during installation. The plate is deliberately not 
pre-drilled, since it is difficult to line up fastenings in a doorjamb 
with pre-drilled fastening openings in the plate. Instead, the plate is 
shimmed into position and held by shims or wedges in position while a 
drill is used to drill directly through the face of the doorjamb into the 
plate at the locations at which it is desired to secure the plate to the 
doorjamb. Self-tapping one-way fastenings are then threaded through the 
bores drilled in the doorjamb directly into the plate where they thread 
into the plate and hold it securely against the doorjamb. The plate is 
thus securely held in place and reinforces the jamb. Openings are also 
drilled through the striker plate screw holes directly into the 
reinforcing plate and the striker plate is then secured firmly to the 
reinforcing or backing plate by the same self-tapping threaded fastenings. 
Alternatively, the striker plate on the door may be secured to the backing 
or reinforcing plate by machine bolt fastenings which are easily 
accessible from the side of the doorjamb if the trim or interior casing 
over the door frame is removed. As a further alternative, special 
fastenings having a fairly wide base or supporting surface at both ends 
can be provided as a connecting means between the striker plate and the 
reinforcing plate on opposite sides of the doorjamb. These reinforcing 
means are fitted into simple drilled orifices extending through the 
doorjamb and provide both a metal-to-metal contact between the parts as 
well as a strong and secure boxlike structure arrangement. 
The reinforcing plate and fastenings of the invention are preferably 
supplied to the trade in a prepackaged form including the necessary plate, 
one-way fastenings and matching sized drill bits for installation of the 
plate and fastening against the door jamb. A more complete understanding 
of the invention will be gained by reference to the following detailed 
description with reference to the appended drawings. 
FIG. 1 is an isometric view of a portion of a typical door frame partially 
broken away to show the reinforcing plate of the invention 11 positioned 
on the back of the doorjamb 13 within the space 15 normally found between 
the doorjamb 13 and the door frame 17. The door frame 17 is composed or 
formed, as is customary, from a pair of two by four timbers 19 and 21 to 
the sides of which are placed encasing timbers or sheet members 23 and 25, 
the whole forming a part of the door frame or door frame assembly. The 
encasing member 23 may be exterior sheathing or siding and the encasing 
member 25 may be drywall or plaster or lath or the like. A section of an 
exterior door casing 27 extends away from the door frame 17 proper. See 
FIG. 2. This casing, in the case shown in FIG. 2, is comprised of a fairly 
heavy construction comprised of two by fours 27a and 27b with outer 
casings 27c and 27d. This entire structure 27 may be part of an archway or 
overhang over the door and serves as an excellent outside protection for 
the inner portions of the door frame. A door trim piece or interior door 
casing 29 covers the side of the door basically covering the space between 
the frame 17 and the doorjamb 13. In many constructions, the exterior door 
casing 27 may not be present except as an outside trim casing similar to 
the inside trim casing 29, but usually more extensive and more securely 
attached to the door frame. A striker plate 31 is provided on the outside 
of the doorjamb 13 in a position to interact with the latch or bolt of the 
door lock normally held in the door 33 as shown more particularly in FIG. 
2 which is a top-section view of the isometric view of a door assembly 
shown in FIG. 1. 
In FIG. 2, screw threaded fastenings 35 are shown securing the striker 
plate 31 to the reinforcing plate 11 of the invention. Such screw threaded 
fastenings 35 may normally be a self-tapping fastening which, as will be 
presently described, also connects the reinforcing plate 11 of the 
invention to the doorjamb 13, reinforcing the jamb as a whole. However, it 
should be understood that other types of threaded fastenings such as 
machine bolts and the like could also be used to attach the striker plate 
31 securely to the reinforcing plate 11 through the wood of the door-jamb 
13. If these threaded fastenings are pulled fairly tight, the force 
obtained between the striker plate and the reinforcing plate upon the wood 
between them forms, in effect, a very strong laminated structure which is 
practically indestructible by any normal exteriorly applied force. 
Alternatively, however, as will be explained presently, a special threaded 
reinforcing fastening member may replace part of the wood between the 
striker plate and the reinforcing plate of the invention. 
In FIG. 1, there are also shown a number of threaded one-way fastenings 37 
which should be understood to be self-tapping fastenings which have been 
tapped into the reinforcing plate 11 after such plate has been 
pre-drilled. A number of suitable self-tapping fastenings are known in the 
art. In FIG. 1, such self-tapping threaded fastenings are shown in the top 
of the view extending from the plate where the jamb 13 has been cut away. 
In the lower portion of FIG. 1, only the heads of the self-tapping 
fastenings 37 are shown as they are pulled into the doorjamb, fastening it 
tightly to the reinforcing plate 11. Several of the self-tapping screw 
threaded fastenings 37 are also shown in cross section in FIG. 2 where it 
is seen that the leading ends 37A of such self-tapping fastenings have 
extended through the reinforcing plate 11 in order to obtain good purchase 
upon such plate. The ends 37A of the self-tapping threaded fastenings 
extend into the opening or space 15 behind the doorjamb. The head 37B of 
the self-tapping threaded fastenings 37 are as shown with so-called 
one-way slots 37C having the usual flat slot sides in the driving 
direction, but a beveled opposite slot side so a driving tool such as a 
screwdriver cannot gain the necessary purchase for rotation of the screw 
in the opposite direction to remove the screw. This prevents someone on 
the outside of the door from removing the fastenings to detach the 
reinforcing plate 11 from the doorjamb 13. If desired, the heads of the 
fastenings 35 can also have one-way slots, but this is not strictly 
necessary, since the fastenings 35 are normally shielded by the closed 
door in any event. 
It is critical to the successful use and operation of the doorjamb assembly 
and reinforcing plate of the invention that the plate be attached to the 
doorjamb by self-tapping threaded fasteners in accordance with the present 
invention. These self-tapping threaded fasteners are entered into orifices 
drilled in the reinforcing plate after it is mounted in its final position 
behind the doorjamb 13. In mounting the reinforcing plate 11 behind the 
door frame, the trim strip or interior casing 29 is first removed from the 
face of the door frame 17, usually by merely prying such trim strip or 
interior casing away with a crowbar or the like. If the trim strip is 
attached by threaded fastenings to the door frame, it can be removed by 
initially removing said fastenings. When the door trim strip or interior 
door casing 29 is removed, access to the space 15 behind the doorjamb is 
had and the reinforcing plate 11 may be merely slipped into such space and 
held by triangular shims 39 shown in an end view in FIG. 2. Such shims are 
forced together so that their wedging action wedges the reinforcing plate 
11 securely against the back of the doorjamb 13. Since the reinforcing 
plate 11 is a rigid plate formed of at least 16 gauge steel, it is 
relatively easy to wedge it against the doorjamb to hold it in place 
during the drilling of matching orifices through the doorjamb and through 
the reinforcing plate. If too thin a reinforcing plate was used, not only 
would it not adequately reinforce the doorjamb after being installed, but 
it would be more difficult to effectively jam into place by the wedging 
action of the shims, since the metal plate might bend in sections, 
particularly when the drilling pressure is applied to it through the 
doorjamb interfering with the drilling action and also the location of the 
openings which in order to be really effective and easily obtained, should 
be precisely lined up with the drilled orifices in the doorjamb itself. 
Plates having openings already formed in them for fastenings to the jamb, 
therefore, are not practical, since it is next to impossible, or at least 
very difficult, particularly for a homeowner, to line up such orifices 
with each other. Once the self-tapping, one-way screw-threaded fastenings 
37 are pulled tight against the doorjamb by their purchase within the 
steel of the reinforcing plate 11, the doorjamb itself is very effectively 
reinforced as far as the plate 11 extends. Normally such plate should 
extend along the door for a considerable distance such as, for example, at 
least about 12 to 20 inches and up to 2 or 3 feet or more. As will be 
understood, the longer the reinforcing plate, the more reinforcing action 
will be obtained. With a reasonable-sized reinforcing plate, it will be 
practically impossible to kick down the door or to spring the door by 
kicking upon the door itself unless the bolt to the lock itself fractures 
or is torn from the door. There are a number of very strong wooden doors 
and also, at the present time, a widespread use of steel doors, so it is 
practically impossible when a strong door is used to detach the door from 
the doorjamb reinforced with the reinforcing plate of the present 
invention. 
FIG. 3 shows a side view of the doorjamb having the usual two striker 
plates 31A and 31B, the striker plate 31A accommodating the normal latch 
or lock bolt of the door and striker plate 31B, as will be understood, 
being positioned to provide a locking surface for the usual secondary 
deadbolt frequently used in the present day to provide additional security 
for a door. In FIG. 3, the reinforcing plate 11 of the invention is shown 
in dotted outline to illustrate how extensive the area covered by such 
plate is and the extensive area of the doorjamb 13 which is reinforced by 
such plate. Again, it is emphasized that the success of the present 
invention requires that the reinforcing plate 11 be originally without 
orifices for the fastenings, or at least that sufficient closed area be 
available on such plate so that a number of small orifices may be drilled 
straight through the plate while it is mounted behind the doorjamb after 
which the self-tapping fastenings may be passed through the doorjamb and 
into the newly drilled openings allowing the reinforcing plate to then be 
pulled very tightly against the doorjamb by rotation of the self-tapping 
screw-threaded fastenings 37. 
There are actually, in general, two types of door frames installed in most 
residences, a fairly wide-type used normally for the main entrances and a 
narrower-type used for side entrances and the like. Such narrower-type may 
also frequently be used on enclosed porches and the like and on doors 
mounted in combination with side windows. It is desirable, therefore, to 
provide two widths of the reinforcing plate 11 of the invention. These are 
shown in FIG. 4 which shows a plate about 20 inches long and 4 inches wide 
while FIG. 5 shows a plate also about 20 inches long and about 23/4 inches 
wide. These sizes are generally preferred, but any other size that can 
easily fit in the normal opening between the doorjamb and the door frame 
can be used. With these two preferred sized reinforcing plates, almost 
every normal doorjamb can be readily reinforced in accordance with the 
invention. It will be noted that both of the plates in FIGS. 4 and 5 are 
without any openings either for the self-tapping screw fastenings of the 
invention, or for extension of a long lock bolt through the reinforcing 
plate. As will be presently explained, however, openings for a lock bolt 
can be, in a preferred embodiment of the invention, provided ahead of 
time. However, it is desirable not to pre-apply openings for the 
self-tapping fastenings ahead of time, since such provision makes it very 
difficult to line up the fastenings with the holes in the jamb in the 
reinforcing plate. Instead, it is desirable and with respect to the 
present invention, substantially critical, not to provide the final holes 
for the self-tapping screw-threaded fastenings until the reinforcing plate 
of the invention is actually installed behind the doorjamb and held, 
preferably by a jamb-type arrangement of shims or the like. Of course, it 
will be understood that a pre-drilled plate having openings provided for 
some other purpose such as a lock bolt or the like, or for some other 
purpose, can be provided. However, in the present invention, the 
self-tapping screw-threaded fastenings 37 are most conveniently and 
effectively entered into freshly-drilled openings aligned with similar 
drilled openings in the doorjamb as a result of having been just drilled 
while a jamb is fixedly held against the back of the doorjamb. 
FIG. 6 shows a kit for purchase from outlets for hardware supplies and the 
like including a reinforcing plate 11 in accordance with the invention, a 
pair of drill bits 39, for drilling openings in the plate 11 of the 
precise size for self-tapping, one-way screws or screw-threaded fastenings 
37 during the time that the plate 11 is held in position as explained 
above against a doorjamb or the back of a doorjamb by shim means 41 or 
other effective means to hold the plate 11 in place while it is being 
drilled with the tap holes for the self-tapping fasteners 37. The various 
assembly parts or units mentioned are contained within the usual 
commercial packaging comprising, as shown, a cardboard backing 43 
surrounded by the usual plastic shrink-wrapping 45 or the like. As will be 
realized by those skilled in the packaging arts, a number of different 
packaging arrangements can be used to produce the kits shown in FIG. 6. It 
will also be realized that various combinations of the essential parts 
used for practicing the invention can be included in the kit as shown 
generally in FIG. 6, only one such combination and arrangement being shown 
in FIG. 6. 
FIG. 7 shows a striker plate 32A which is wider so as to accommodate more 
fastening openings. Such a striker plate is advantageous with the present 
invention, since it is important that the striker plate be fairly rigidly 
secured to the reinforcing plate 11. 
The striker plate 32B, shown in FIG. 8, is longer than normal and may be 
supplied with additional fastening means upwardly and downwardly from the 
bolt hole 47 in the plate. As will be understood, since the reinforcing 
plate 11 may be from 2 to 3 feet or more in length, it may frequently be 
advantageous to use a longer-than-normal striker plate which can then be 
secured to the reinforcing plate at various locations forming, 
particularly when it is pulled up tight against the wood between the 
reinforcing plate and the striker plate, a very strong construction. 
FIG. 9 is a side view of a special reinforcing fastening 49 having a 
self-tapping threaded member 51 on the bottom or first end for securing to 
the reinforcing plate of the invention, and a threaded opening 53 in the 
top or second end into which a normal threaded fastening usually of a 
machine bolt-type, can be threaded to support a striker plate with 
metal-to-metal contact against the reinforcing plate 11. 
In the use of the reinforcing fastening shown in FIG. 9, a 
larger-than-normal opening is drilled with a drill bit supplied along with 
the other equipment in a kit, in the doorjamb and then a smaller opening 
for accommodating the self-tapping fastening 51 at the end is drilled in 
the plate 11. The distance between the bottom of the reinforcing fitting 
49 and the top of such fitting should be exactly the thickness of the jamb 
section between the reinforcing plate 11 and the striker plate 31. Since 
the distance or the thickness of the doorjamb at the location of the 
striker plate may vary somewhat, it may be desirable to have several 
lengths of the reinforcing fitting 49 available. Alternatively, washers or 
washer-like sections 55 can be supplied or accommodated on the bottom of 
the fitting 49. Such washer-like sections 55 are exactly the same size as 
the outside of the fitting itself and an inner opening or orifice in the 
washer-like sections surrounds the self-tapping threaded section 51. The 
fitting 49 will normally be supplied with several of the washer-like 
sections 55 installed on it, which sections can then be removed until the 
reinforcing fitting 49, as a whole, is approximately the same height as 
the opening in the jamb of the door. It is preferable for the washer-like 
sections 55 to be at least partially attached to each other by some means 
such as adhesive, thin metal sections, or the like. The metal pieces can 
be thin slices, partially severed in the lower portion of the fitting, in 
which case a thin metal section at one side can retain all the sections 
together until one or more are pried off with a wedging tool or the like 
to shorten the entire unit. 
FIG. 10 shows two of the reinforcing fasteners 49 installed in openings in 
the jamb 13 in position for the installation of a striker plate 31 on top 
of the reinforcing fastenings 49 by means of threaded fastenings 57 shown 
disposed next to the striker plate. 
FIG. 11 is a further side view showing the installation of the reinforcing 
fastening means 49 to rigidly secure the striker plate 31 to the 
reinforcing plate 11. 
FIG. 12 is a further view similar to FIG. 11 but omitting the wooden 
structure of the door frame and showing merely the metal portions of the 
assembly including the reinforcing plate 11, the reinforcing fastenings 
49, the striker plate 31 and the self-tapping fastening sections 51 at the 
end of the reinforcing fittings 49 extending through the reinforcing plate 
11 of the invention plus screw-threaded fastenings 57 which secure the 
striker plate to the top of the reinforcing fastenings 49. 
FIG. 13 shows a special striker plate 59 having fastener orifices not only 
adjacent to the bolt hole 47, but shifted to the side away from the edge 
of the striker plate and the edge of the jamb of the door. Such auxiliary 
fastening openings 61 provide a convenient place to attach the striker 
plate 59 to the reinforcing threaded fastenings 49 described above which, 
in turn, are secured to the reinforcing plate 11 by the self-tapping 
fastening sections 51, better shown in FIGS. 9, 11 and 12. The reinforcing 
fastening 49 is shown in dotted lines in FIG. 13, where it underlies the 
striker plate 59. The striker plate 59 is also provided with the more 
conventional fastener openings 63 beside the bolt opening 47. The 
arrangement shown in FIG. 13 using the special striker plate and 
arrangement of the use of the reinforcing fastenings 49 solves the 
principal problem involved in use of the reinforcing fastenings 49 in the 
other embodiments, which is that since the reinforcing fastenings 49 have 
a larger diameter than the usual screw fastening and the usual fastening 
openings in the striker plate are also fairly close to the edge of the 
doorjamb, removal of the extra material from the doorjamb to accommodate 
the reinforcing fastening 49 in essence causes a weak point in the 
structure of the jamb itself, which weakness is not completely cured by 
the solid base provided by the reinforcing fastening 49. However, in FIG. 
13, it will be recognized that the reinforcing fastenings 49, having been 
removed from the edge of the doorjamb, are now sufficiently far from such 
edge so that removal of the extra material from the jamb to accommodate 
the reinforcing fastening 49 does not seriously weaken, or in most cases, 
weaken at all, the doorjamb itself, and the extra metal-to-metal contact 
provided by the reinforcing fastening 49 provides a stronger connection of 
the striker plate 59 to the reinforcing plate 11 of the invention. Even 
though the reinforcing fastenings 49 provide a secure metal-to-metal 
contact between the reinforcing plate 11 and the striker plate 59, 
forming, in effect, a metal reinforced box-type structure independent of 
the intervening wood of the doorjamb, it still may be advisable or 
preferable to make the reinforcing fastening 49 shorter than the nominal 
height of the doorjamb at the point or location at which the reinforcing 
fastening passes through the doorjamb. This allows the striker plate to be 
drawn down against the reinforcing fastening 49 sufficiently to compress 
the wood of the doorjamb between the striker plate 59 and the reinforcing 
plate 11 of the invention, thus additionally obtaining security from the 
laminated structure formed thereby comprising a wooden compressed section 
held on both sides by a metal-to-metal contact through the reinforcing 
fitting 49 and thus gaining the strongest, most rigid possible connection 
of the striker plate 59 with the reinforcing plate 11. 
FIG. 14 shows a further kit containing the parts necessary to practice the 
invention similar to the kit shown in FIG. 6, but including additional 
parts which may be useful or even preferred. In FIG. 14, there is shown 
included in a kit 65, two reinforcing plates, namely plates 11A and 11B, 
shown for example in FIGS. 4 and 5, which constitute respectively, a 
relatively wide plate 11A and a second relatively narrow plate 11B. It 
will be understood that the wider plate 11A will normally be used in 
locations where there is a wider doorjamb and the narrower plate 11B will 
be used in those locations in a residence or the like usually on side 
doors, patio doors and the like where the jamb is relatively narrow. Also 
included in the kit 65 are two different striker plates 31A and 31B which 
in the case of 32A is substantially the same as that shown in FIG. 7 and 
in the case of 31B, is a conventional striker plate. The special 
reinforcing fastening 49 shown in FIG. 9 is also included in the kit 65 
shown in FIG. 14 and in fact two of such fastenings are shown. In addition 
there are included in the kit 65 the self-tapping, one-way fastenings 37 
which are used for tightly securing the doorjamb to the reinforcing plate 
11 in the form of plates 11A or 11B. It will be understood that the 
special reinforcing plate 59 shown in FIG. 13 could also be included in 
the kit 65 in FIG. 14 or for that matter in kit 43 shown in FIG. 6. Two 
different-sized drill bits, 39A and 39B, are shown in the kit in FIG. 14, 
39A being for drilling bores for the self-tapping fastenings 37 and drill 
bit 39B having a larger diameter for providing bores in the doorjamb to 
accommodate the special reinforcing fastening 49 of the invention. 
FIG. 15 shows a reinforcing plate 69 in accordance with the invention 
having a bolt orifice 67 for use where the bolt of a lock on the door is 
designed to pass entirely through the doorjamb. It will be noted that the 
single orifice 67 is located on the reinforcing plate 69 substantially on 
one side in the center. In installing such plate the orifice 67 can be 
fairly easily lined up with the bolt on the door and then secured in place 
by the self-tapping screws passing through holes drilled in both the 
doorjamb and the reinforcing plate by the use of the drill bit supplied in 
the kit. Normally the locking bolts supplied with the usual front door 
lock do not pass completely through the doorjamb and therefore there is no 
reason to have the additional orifice 67 in the backing plate for the 
normal lock. However, it is frequently customary to have an additional 
deadbolt mounted either approximately four or eight inches above the 
regular or normal lock to bring the deadbolt more nearly into the center 
of the edge of the door. The orifice 67 therefore can be adjusted to be 
under or in line with the deadbolt or adjacent to the deadbolt entrance 
point into the doorjamb to reinforce the deadbolt. Since the deadbolt is 
usually placed more in the center of the door than the normal locking 
bolt, the position of the orifice 67 is approximately correct as shown. 
FIG. 16 shows a preferred form of the plate 11 of the invention arranged to 
be more easily adjustable for the two major distances which deadbolts are 
normally found placed or located from the normal locking bolt. There are 
two orifices 71 and 73 provided in the plate 75 shown in FIG. 16. Such 
location of the orifices 71 and 73 allows a more careful or accurate 
positioning of the plate so as to be more or less centralized with respect 
to the regular locking bolt as well as the deadbolt, if any, without 
skewing the reinforcing plate 75 too far away from its normal positioning 
center more or less about the regular locking bolt of the door. It will be 
understood that either of the plates 69 or 75 could be substituted into 
either of the kits shown in FIGS. 6 or 14 in place of or in addition to 
the plates already shown in such kits. 
It will be understood from the above description of various embodiments in 
connection with the illustrations shown in the various figures that the 
present invention provides a very convenient and efficient arrangement and 
method for installing a reinforcing plate adjacent a lock in a door to 
reinforce the doorjamb against kicking open the door or other forceable 
entry of such door. While the invention is simple, it is also highly 
efficient and sophisticated in that the parts have been minimized to 
increase the practicality and the reinforcing arrangement is applicable to 
a wide variety of doors and the like. The invention depends essentially on 
the provision of all the essential parts in a convenient kit and the use 
of self-tapping screws to be driven into the reinforcing plate after it 
has been drilled in place to assure complete alignment between the holes 
drilled in the jamb and the plate. As explained above, many devices and 
arrangements have been suggested for reinforcing the jamb of a door 
against break-ins and particularly kick-ins of such door by trespasses and 
the like, but few of such previous arrangements have ever entered into 
actual use. The present applicant's invention has simplified the previous 
arrangements and refined their concepts down to the bare essentials 
providing thereby an unexpectedly efficient and effective means and method 
for reinforcing the doorjambs in residences and the like. The invention, 
furthermore, not only reinforces the doorjamb itself but also very 
effectively reinforces the striker plate by attaching it very securely to 
the reinforcing plate of the invention. Furthermore, in one somewhat more 
sophisticated, but also preferred arrangement the reinforcement or 
attachment of the striker plate with the reinforcing plate is 
substantially increased by the use of a flat-planed reinforcing fastening 
means between the striker plate and the reinforcing plate which even more 
effectively unifies the two into a single ridged structural assemblage. 
While the present invention has been described at some length and with some 
particularity with respect to several described embodiments, it is not 
intended that it should be limited to any such particulars or embodiments 
or any particular embodiment, but is to be construed broadly with 
reference to the appended claims so as to provide the broadest possible 
interpretation of such claims in view of the prior art and therefore to 
effectively encompass the intended scope of the invention.