Contractor and Facility Manager Education Series #7 — Locksets, Mortise Locks, and Exit Devices: Choosing the Right Function for Every Opening

The lock on a commercial door does more than keep people out. It controls who can enter, how, and under what conditions — and when egress is required, it has to get out of the way completely and reliably. Getting the function wrong doesn't just mean the door operates inconveniently; in some cases it means a code violation, a life safety issue, or both.

This article covers the three main categories of commercial locking hardware — cylindrical locksets, mortise locks, and exit devices — and explains how to match the right function to the door's purpose.

Cylindrical vs. Mortise: The Core Difference

The two primary lockset formats in commercial construction are cylindrical (also called tubular or bored) and mortise, and they differ fundamentally in how they're constructed and installed.

A cylindrical lockset installs through two bored holes in the door face — one large hole for the lock body and one smaller hole in the door edge for the latch. The mechanism is housed in a cylindrical case that sits within the door. Cylindrical locks are faster to install, require less door material to be removed, and are generally less expensive than mortise locks. They're the right choice for the majority of interior commercial openings and lighter-duty exterior applications.

A mortise lockset installs into a large rectangular pocket routed into the lock stile of the door — the "mortise." The lock case sits inside the door edge, with trim (handles and roses or escutcheons) on the face. Mortise locks are a more robust construction — the mechanism is larger, the case is more substantial, and the interface between the lock and the door edge is more secure. They're the specification for high-use exterior doors, security-sensitive openings, and applications where the additional durability and functionality of a mortise case is warranted. The door must be prepped specifically for a mortise lock — it's not a field modification.

ANSI Functions

ANSI (American National Standards Institute) publishes a standardized set of lock functions that describe how a lockset operates — which side is always free, which side requires a key or credential, and how the functions interact. These function codes appear on hardware schedules and are how you determine whether a lock does what it needs to do at a given opening.

The functions you'll encounter most often in commercial work:

F04 — Storeroom: Outside always locked, inside always free. Requires key to enter from outside. Common on storage rooms, mechanical rooms, and utility spaces where entry needs to be controlled but occupants can always exit freely.

F05 — Classroom: Outside can be locked or unlocked with a key from either side. Inside lever is always free. The "classroom function" is named for its original application but is widely used for offices and other rooms where the lock state is toggled by staff.

F07 — Entrance: Outside locked until retracted by key or credential; inside always free. Common on main building entries and other controlled-access doors.

F13 — Communicating: Both sides lockable independently by key. Used between adjacent spaces where each side may need to independently control access.

F19 — Privacy: Inside button locks outside lever; emergency coin release on outside. Restrooms, individual patient rooms, small conference rooms.

Understanding the function is what connects the lock to the door's purpose. A storeroom lock on an office door means staff get locked out when the door closes. A classroom lock on a storeroom means someone can lock the outside while still inside. Matching function to use isn't optional — it's the specification.

Exit Devices (Panic Hardware)

Exit devices — also called panic hardware or crash bars — are required by code at certain doors, and for good reason. When a building is evacuating, occupants need to be able to exit through a door by applying body pressure to a bar, without fumbling with a lever, knob, or key. The exit device provides that capability.

IBC and NFPA 101 (the Life Safety Code) both define where exit devices are required. The general rule: doors serving assembly occupancies with an occupant load of 50 or more require panic hardware, as do high-hazard occupancies and certain exit enclosure doors. Beyond the code minimums, exit devices are appropriate at any exterior door in a commercial building where a lockset would create a barrier to egress in an emergency.

Exit device types:

A rim exit device mounts on the surface of the door, with the bar mechanism and latch on the face and a rim strike on the frame. Rim devices are the most straightforward and most common. They're available in a wide range of functions for the exterior trim (locked outside, key-retracts-latchbolt, lever trim, and many others).

A mortise exit device uses a mortise lock case as the locking mechanism, providing the security and functionality of a mortise lock with panic bar activation. These are specified for high-security or high-use exterior openings where the security characteristics of a mortise case are required.

A vertical rod exit device uses rods that run to top and bottom latching points — into the header and the threshold or floor — rather than latching at the strike. Vertical rods are used on pairs of doors without a mullion (so-called "mullion-free pairs"), on doors where a frame strike isn't practical, and on some high-security applications. They can be surface-mounted or concealed (CVR — concealed vertical rod), with concealed versions providing a cleaner appearance.

Exit device functions follow a similar ANSI coding convention: the "outside trim" determines how the outside of the door operates. A "no outside trim" function (exit only) allows egress but provides no entry. A "key retracts latchbolt" function allows entry with a key. Lever trim provides a standard lever handle that can be locked or unlocked.

Fire-Rated Exit Devices

Exit devices on fire-rated doors must be listed for fire exit hardware — not all exit devices carry that listing. Fire exit hardware must positively latch the door and must meet the requirements of the fire assembly it's part of. When specifying exit devices on fire-rated openings, confirm that the device carries the appropriate fire label.

Dogging

Many exit devices include a "dogging" feature that allows the latchbolt to be held retracted — effectively converting the door to a push/pull operation without activating the exit bar. Dogging is useful in high-traffic areas during business hours. It cannot be used on fire-rated doors — fire doors must positively latch, and a dogged-open latchbolt defeats that requirement.

Electrified Options

Both locksets and exit devices are available in electrified configurations that integrate with access control systems. Electric latch retraction (ELR) on exit devices allows the latchbolt to be retracted by an electrical signal — enabling remote release or timed unlocking. Electrified mortise locks can combine the functions of a lockset with electronic access control. We'll cover electrified hardware in depth in Part 9.

Matching Function to Opening

The decision tree for any commercial opening's lock hardware starts with: What is the door's purpose? Who needs to enter, from which side, under what conditions? What egress requirements apply? Is it fire-rated?

A well-matched hardware function is invisible in use — it does exactly what it needs to do without friction, confusion, or workaround. A mismatched function creates problems that show up daily and are usually expensive to fix after the fact because the door prep is already done.

Hardware schedules exist to document these decisions systematically, and reviewing them carefully — before the order goes in — is the most effective quality control step in the commercial door and hardware process.

Next in this series: door closers and automatic operators — how closers work, how to size them, ADA requirements, and when an automatic operator is the right answer.

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