Commercial door locks explained: which type is on your door?

Quick identification table

Cylindrical lever locks: quick to fit, made for lighter doors

This lock goes into two drilled holes: a large bore through the face of the door and a smaller one through the edge for the latch. Lever, latch and cylinder come as one unit, so swapping one out is fast.

You will find them on interior offices, break rooms and the side doors of strip plaza units and light industrial bays. Commercial doors use levers rather than knobs because a lever works with a full arm, a gloved hand or a weak grip.

The governing standard is ANSI/BHMA A156.2, which covers bored and preassembled locks and latches (ANSI).

Mortise locks: the workhorse of busy entrances

A mortise lock lives in a deep rectangular pocket cut into the door's edge. Its body is bigger and heavier than a cylindrical lock's, and many combine the latch and deadbolt in a single case.

These are the locks for doors that never get a rest: the front of an office building, a medical clinic, a school, or the original entrance of an older brick or stone building downtown where the door has been kept. Many older wooden buildings on the peninsula still have mortise hardware that can be serviced rather than replaced. The standard is ANSI/BHMA A156.13 (ANSI).

Storefront deadlocks: built for narrow glass doors

Glass shop doors are framed in thin aluminum, the stile, with no room for a standard deadbolt. They take a narrow-backset mortise deadlock instead, usually with a key cylinder on the outside and a thumbturn or a second cylinder inside.

The bolt on many storefront locks is a hook or pivot that swings up into the frame, so a pry bar between door and frame meets more resistance. These doors are also where you often find a panic bar or a reader paired with an electric strike.

One caution on key-both-sides locks. Allegion advises that double-cylinder locks should not be used on any door required for egress (Allegion). If your shop door needs a key to get out, find out whether it is a required exit before you rely on it.

Exit devices: getting out without a key

An exit device runs across the inside of the door. A push on the bar or touchpad releases the latch, with no key, knob or know-how needed. In an emergency, anyone can leave.

The standard for exit devices is ANSI/BHMA A156.3 (ANSI). Outside, the door may have nothing at all, a pull handle, or a lever or cylinder for keyed entry.

Whether a door must have panic hardware depends on the building, how it is used and the codes that apply, so never take one off or swap it for something else without checking first.

Adding keyed entry from outside

The outside hardware on a panic bar door is called trim. For keyed entry there are two usual options:

• Lever trim. An outside lever that a key locks or unlocks, so staff go in the same door they leave by.
• Rim cylinder. A key cylinder that pulls back the latch while the key is turned. Good for service and rear doors used by a few people.

Trim can often be added to an existing bar, as long as it matches the bar's make and model.

Signs an exit device needs attention

Watch for a bar that sticks or takes a hard shove, a latch that doesn't catch as the door swings shut, a door that won't stay locked, or a dogging feature that no longer holds the bar in. Busy exit devices usually give warning before they fail, and acting early is cheaper in downtime. We repair and install exit devices and their outside trim: see our commercial locksmith page.

Cores, restricted keys and master keying

The cylinder, where the key goes, is where most of a commercial lock's security and convenience is decided.

• Interchangeable cores. A control key pulls the keyed core out so another can drop in. When someone leaves with a key, you change the core rather than rekeying the whole lock.
• Restricted keys. The blank is controlled, so duplicates can't be cut at a hardware counter. Only authorised people can order more.
• Master keying. Each tenant or team opens their own doors, a manager's key opens a group, and a master opens everything. Cylindrical, mortise and storefront locks can all share one system.

If you are weighing more keys against cards or fobs, our guide to choosing an access control system for small business sets the two side by side.

What BHMA grades mean

Most BHMA lock standards rank products in three grades, with Grade 1 the highest performance level, then Grade 2 and Grade 3 (ANSI blog). The grade reflects results in standard tests covering things like cycle life, strength and security.

In practice, a heavily used commercial door wants Grade 1, and a quieter interior door may do fine with Grade 2. A residential-grade lock on a busy back door wears out quickly.

How does salt air treat commercial door hardware?

In Halifax, the lock often gets blamed for problems the weather started.

• Salt corrosion. Doors near the harbour and on busy salted streets see salt in the air and on boots. It works into cylinders, latches and the feet of exit devices, and a cylinder that turns stiffly today can seize later.
• Freeze-thaw. Rain or meltwater gets into a cylinder or strike during a mild day and freezes overnight, so the key won't turn or the bolt won't throw.
• Wind and damp. Gusts hold a door against its closer so it rests on the frame without latching, and weeks of fog and drizzle keep hardware wet. A door that looks shut but hasn't latched isn't locked.
• Shifting frames. Seasonal movement puts the bolt slightly out of line with the strike, so it drags or misses.

A check of every outside door, closer and strike each fall heads off many winter callouts. The residential version of the same idea is in how to secure front door from break ins, and landlords running mixed buildings may want the key log habits from change locks after tenant moves out.

For help choosing hardware, rekeying, repairing an exit device or setting up master keys, see our commercial locksmith page.

In brief

• Cylindrical levers suit offices and lighter-use doors.
• Mortise locks suit main entrances that open all day.
• Glass storefront doors need a narrow-stile deadlock.
• Exit devices put egress first; lever trim or a rim cylinder adds keyed entry.
• Interchangeable cores and restricted keys make staff turnover easier, and salt air makes regular servicing worth it.