Any door labeled as fire rated requires special knowledge and careful consideration before any “in the field” modification begins. Some examples of acceptable modifications are drilling thru-bolt holes for a lever lock or drilling round holes to accommodate lock cylinders, spindles and similar operational elements. An example of an unacceptable modification is removing a mortise lock from a fire rated door and installing a cylindrical lock using a wrap to cover the door face and door edge openings.
When modifications go beyond what is specified in the NFPA 80 for field modifications, they may void the fire rating. However, a certified door shop can remove the door, transport the door to their facility, make modifications at their business, recertify the door and jamb in accordance with the specifications established with the listing and labeling agency servicing their business and return the door to the building and install it. It is recommended that the building owner and LAHJ be contacted if a fire door will be removed from the opening and the building is occupied.
We will discuss different options for converting a 161 prepped door for commercial cylindrical locks to an exit device application while maintaining the fire rating on the door.
A 161 door prep is a standard door preparation using a 2-1/8” diameter cross bore opening on each face of the door at a 2-3/4” backset. There is a 1” diameter edge bore for the latch that has a standard 1-1/8” wide by 2-1/4” tall faceplate. Depending upon the lock, the strike plate opening into the jamb can accommodate a 4-7/8” ANSI Strike or a standard 2-3/4” strike.
Exit devices, like cylindrical locks and mortise locks, can be ordered to function in a specific operation. The functionality is determined by the trim, as Life Safety Codes require free egress from the interior. The three most common functions are no locking trim (no outside operation), night latch key retracts Pullman bolt and key unlocks or locks trim. Some exit device manufacturers offer clutch or freewheeling trim to resist vandalism.
For the conversion to satisfy the inspection and certification agencies (i.e. Warnock Hersey) and maintain the fire door rating, the wide stile center case of the push (flat) bar type of fire rated exit device or the wide stile active head assembly of the crossbar fire rated exit device must be larger than 2-1/8” diameter to fully cover the cross bore opening on the interior side of the door. Consider using a wide stile exit device such as the Corbin Russwin ED8000 Series, Sargent 8888 Series, the Von Duprin 22 Series or the Yale 2100 Series. The above listed exit devices are available with three hour fire ratings on single doors up to a 4’0” by 8’0” opening.
These exit devices are normally installed at a 2-3/4” centered backset, ensuring the center case or active head can be positioned over the 2-1/8” diameter cross bore opening.
Another choice is the Detex Advantex 10 Series Rim Fire Exit Device. Its wide stile center case is approximately 2-1/2” wide by 8” tall. Be certain the rim exit device center case is mounted in the position to completely cover the opening. Many rim exit devices are designed for installation at a 2-3/4” backset.
To cover the latch opening in the door edge and the strike opening in the jamb, a ferrous metal fill plate must be installed in place of the latch bolt and should cover the strike opening in the jamb. Some lock manufacturers including Falcon and Monarch offer these accessories as well as Don-Jo Mfg., M.A.G. Eng. & Mfg. and ENTRY ARMOR by PRO-LOK.
To return the door as close to the originally designed configuration, remove the faceplate from the latch bolt and remove the rear portion of the mechanism. Place this modified latch into the edge bore opening and install the filler plate over it. This will fill the void left when the latch bolt was removed.
By installing the modified portion of the latch bolt into the door edge, you are showing the LAHJ that you understand the importance of maintaining the fire rating.
Each lock manufacturer offers a variety of exterior trim for their exit devices, such as thumb piece handlesets, pulls, key-in-lever rose trim, escutcheon trim and trim plates with or without a lock cylinder opening. The type of trim installed should be consistent with code requirements, access needs and aesthetics.