Note: Descriptions are shown in the official language in which they were submitted.
JJ-9369-lCA 2 1 6 4 4 5 2
APPARATUS FOR RETROFITTING AN EXISTING DOOR TO PROVIDE A
FIRE RATING TO THE UNRATED EXISTING DOOR
FIELD OF THE INVENTION
The present invention relates to an apparatus for
attachment to a non-fire rated wooden door for retrofitting
the door to provide for at least twenty minute fire rating
for such door.
BACKGROUND OF THE INVENTION
Present regulations in many jurisdictions require
that doors in public building have at least a twenty minute
fire rating. This rating provides that the door should act
as a fire break to prevent passage of the fire through the
door for at least a period of twenty minutes. Some
jurisdictions also have regulations requiring upgrading of
fire protection ratings of existing doors in existing
buildings either at time of renovation of the space or, in
some cases, within a fixed period of time. Up to the
present time, in order to upgrade the fire protection
rating of the door, it has been necessary to replace the
existing door by a new fire rated door. In some instances,
replacement of such doors may be difficult and may require
replacement of the frame of the doors as well. In
addition, in unique historic buildings, the replacement of
the doors is also difficult due to the unique value of the
existing doors. It would thus be desirable to have a means
of upgrading existing doors in a building to the proper
fire rating.
SUMMARY OF THE INVENTION
The present invention provides for an apparatus for
retrofitting an existing wooden door to upgrade the fire
rating of the existing door. The apparatus comprises a
door cover steel sheet having a non-combustible insulating
coating on an interior surface for covering at least one
surface of the door and a lock set reinforcement bracket
J.~'-9369-lCA 2 ~ 6 4 4 52
having a non-combustible insulating coating on an interior
surface for surrounding the lock set opening on the
opposite surface of the door, the apparatus providing at
least a twenty minute fire rating to the retrofitted door.
In an aspect of the invention, there is provided a
method for increasing the fire rating of a door. The method
comprises attaching to one surface of the door, a door
cover steel sheet having a non-combustible insulating
coating on an interior surface to cover the entire surface
of the door and attaching to the second surface of the
door, a lock set bracket having a non-combustible
insulating coating on an interior surface to surround at
least the lock set opening in the surface of the door, the
modified door having at least a twenty minute fire rating.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention are shown in
the drawings, wherein:
Figure 1 is an exploded perspective view of the
apparatus of the present invention for attachment to an
existing door;
Figure 2 is a perspective view of the apparatus of
the present invention;
Figure 3 is a perspective view of the steel sheet
attached to a door, and;
Figure 4 is a perspective view of the lock set
protector attached to a door.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The apparatus of the present invention for
retrofitting an existing wooden door to upgrade the fire
rating of the existing door is illustrated in the attached
Figures. The apparatus comprises a door cover steel sheet
10 for covering at least one surface of an existing wooden
door 12 and a lock set reinforcement bracket 14 for
JJ-9369-lCA 2 ~ 6 4 4 ~2
surrounding at least the lock set opening 16 of the door 12
on the other surface of the door 12.
The door cover steel sheet 10 is preferably of a 22
to 24 gauge to provide for a minimum twenty minute fire
rating of the door 12. For a minimum twenty minute fire
rating it has been found that the steel sheet is preferably
of 24 gauge.
To improve the fire rating performance of the door,
the interior surface 18 of the door cover steel sheet 10 is
provided with a thin layer of non-combustible insulating
material. The presence of the insulating material on the
interior surface 18 of the door cover steel sheet 10
retards the ignition of the wooden door 12 under fire
conditions by blocking the conductivity of the heat through
the door cover steel sheet 10. Similarly, the lock set
reinforcement bracket 14 is also provided with a thin layer
of non-combustible insulating material on the interior
surface. The non-combustible insulating material is chosen
to provide for proper insulation of the wooden door 12 from
the thermal conductivity of the door cover steel sheet 10.
Preferably, the non-combustible insulating material is
selected from ceramics or mineral type insulation, more
preferably, the non-combustible insulating material is
ceramic paper, most preferably 1/32 inch thick.
Door cover steel sheet 10 is preferably provided
with a folded lip 22 at the top of the sheet to cover the
upper edge 24 of the door 12. If desired, although not
necessary, a similar folded lip or tab may be provided for
the lower or side edges of the door 12. If also desired, a
folded lip may be provided at the side edge to underlay the
hinge plate on the side edge of the door 12 to provide for
joining of the steel sheet 10 to the hinge plates of the
door. Provision of such a lip may further increase the
fire rating of the retrofitted door 12.
Door cover steel sheet 10 is provided with a
suitable opening 26 for lock set 16. For standard doors,
this opening 26 may be preformed in the steel sheet 10 or
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the opening 26 may be cut on site in the proper location
with the use of a suitable hole saw. Lock set
reinforcement bracket 14 is also provided with a circular
opening 28 for passage of the lock set 16 and is provided
with a lip 30 to surround the latch plate 32 of the lock
set 16. This lip 30 as illustrated in the Figures as a
general U-shape to surround the latch plate 32 of the lock
set 16. It has been found that such a shape provides the
proper fire rating for the door 12. If desired, this lip
30 may be formed to have a rectangular opening surrounded
on all sides by metal to increase the amount of metal
surrounding the latch plate 32.
The apparatus for upgrading the fire rating of the
existing door of the present invention may be attached to
the door through any suitable means such as screws or
adhesive and screws 34. If an adhesive is used, it may be
preferred to be a relatively high-temperature adhesive such
that the adhesive will not quickly melt in the high
temperatures encountered in a fire and permit separation of
the door cover steel sheet covering 10 or lock set
reinforcement bracket 14 from the door 12. However, as the
adhesive does not alone hold the apparatus to the door but
is generally only used during the installation, ordinary
carpenter adhesive may be used. The door cover steel sheet
10 and lock set reinforcement bracket 14 are preferably
attached to the door through use of suitable screws 34 and
the adhesive. Preferably the screws 34 are stainless steel
screws chosen because of their lower thermal conductivity
to limit the deterioration of the wood into which they are
attached under fire conditions. As illustrated in the
Figures, the door 12 may be retrofitted without having to
remove the door 12 from the hinges. In these
circumstances, the lock set 16 is removed from the door 12,
a suitable adhesive is applied to one surface of the door
12 and door cover steel sheet covering 10 is applied to the
face of the door and fastened by means of the stainless
steel screws 34. The coated lock set reinforcement bracket
- J3-9369-lCA 2 1 6 4 ~ 52
14 is preferably applied to the other side of the door 12
through the use of stainless steel screws 34 although if
desired adhesive may also be used. At this point, the lock
set 16 is then replaced and the door 12 is available for
use. Alternatively, if tabs or a lip is provided to
underlay the hinge plate on the door 12, the door 12 is
unhung from the frame, hinge plates removed and then
replaced after the door cover steel sheet 10 has been
applied, as described above.
One benefit of the retrofitting method of the
present invention is that has been found that it is only
necessary to completely cover one surface of the door with
the door cover steel sheet in order to achieve the required
minimum twenty minute fire rating. This is important for
retrofitting of buildings having unique doors in that the
interior surface of the door is covered with the door cover
steel sheet and the exterior surface is not modified to a
great degree, thus retaining its aesthetic appeal. In
addition, if desired, decorative panels or other decoration
to match the original appearance of the door may be applied
to the door cover steel sheet to mimic the appearance of
the door. This allows for wider latitude of decoration of
the door not only in retrofit applications but also in new
construction.
The use of the apparatus of the present invention
also increases the security of the door by increasing the
resistance of the doors to impact and break-ins.
Although various preferred embodiments of the
present invention have been described herein in detail, it
will be appreciated by those skilled in the art, that
variations may be made thereto without departing from the
spirit of the invention or the scope of the appended
claims.
