Locksmiths are called out on a regular basis to retrofit lock hardware. In most instances, the hardware should retrofit with minimal or no modification to the door. Some of the reasons to retrofit lock hardware can include replacing a worn lockset or upgrading to a new lockset or one with additional features. Good examples of upgrades are a Schlage ND-Series Lever Lock with Vandlgard clutching action and a Sargent Classroom Security Lever Lock that inserting the key in either the exterior or interior lock cylinder locks or unlocks the outside lever. With this type of lever lock, a schoolteacher can lock the exterior lever from within the classroom.
Retrofitting lock hardware becomes more specific when it is mounted onto a fire rated door or jambs. Fire rated openings, the rated doors and jambs were created to ensure occupant safety within a building.
Standards (rules) identify fire rated doors and the door hardware they can support. The National Fire Protection Association (NFPA) produces the NFPA 80, Standard for Fire Doors and Other Opening Protectives, which is continuously modified and updated. The information covered is widely accepted by local authorities having jurisdiction (LAHJ) and often becomes incorporated into local building codes.
Fire rated doors and jambs are ordered and manufactured to accommodate not only a specific lock type (mortise, cylindrical, exit device), but also are built to accept a specific lock manufacturer’s model product. For fire rated doors, any surface applied hardware modification is restricted to drilling holes that are 3/4” or smaller in diameter with the exception of mortise or rim lock cylinders. Any previous opening must be sealed in a manner acceptable to the LAHJ. Acceptability can vary from one LAHJ to another.
Once the door and jamb has been built, the fire label is attached. This label will usually be UL (Underwriter’s Laboratories) or Warnock Hersey, a brand name of Intertek. The label will usually be located on the hinge edge of the door. On newer fire rated door labels, the label will indicate the rating of the door that determines the length of time the door has been fire tested under a standard fire exposure. Doors are fire rated from 20 minutes up to three hours. Most wood doors have a fire rating of up to one and a half hours. Hollow metal doors can have a fire rating of up to three hours. Labels may also contain important information on the latch throw and installation information based on the listing of the door.
Important: To lower the cost of manufacturing, some door companies only manufacture fire rated doors and sell fire rated doors for non-fire rated openings. Doors that are sold for non-fire rated openings can have a label. However, only a labeled door and jamb can be installed into a fire rated opening.
Fire rated doors are installed in specific areas within a building. The occupancy load (number of people permitted at a given time) usually determines the number and locations of fire rated doors. The size of the building or room and the type of occupancy determines the number of people. Examples of occupancy include theatres, restaurants, banquet rooms and hotels.
A fire rating is normally required on doors that provide a means of egress from a room that borders on a corridor or hallway that leads to an exit. Most exterior doors are not fire rated. However, examples of fire rated exit doors are doors leading to an alley, stairwell doors and generally any door located in a fire rated corridor that provides a pathway to exit the building.
Sometimes fire rated doors are difficult to identify as the label is occasionally removed or painted over. Some labels are metal and riveted onto the door edge or top or bottom. Some labels appear to be decals, with very little thickness. When in doubt, contact the LAHJ.