The difference between a deadlatch and a deadbolt is the difference between a lock that holds on its own and a lock that can be pushed aside. On a commercial storefront door, that difference determines whether the door can be shimmed open with a piece of plastic — or whether it resists.
Deadbolt
A deadbolt is a bolt that moves when the key or thumbturn is turned, and stays where it’s put. There’s no spring holding it in position — the bolt is either extended (locked) or retracted (unlocked), and it doesn’t move until you move it. That’s why it’s called “dead” — no spring pressure.
A deadbolt is the most secure single-point lock because the bolt can’t be pushed back without turning the key or thumbturn. You can’t shim it, you can’t push it, and you can’t card it. The only ways past a deadbolt are picking, drilling, or force.
On a storefront door, a deadbolt is used as a secondary lock — the door is locked with a deadbolt when the business is closed. During business hours, the deadbolt is retracted and the door is held by the primary latch (the deadlatch or the exit device).
Deadlatch
A deadlatch is a spring-loaded latch bolt with an auxiliary feature: a deadlocking pin (sometimes called a deadlock plunger) that sits alongside the main latch bolt. When the door closes, the latch bolt springs into the strike, and the deadlocking pin contacts the strike plate. With the pin depressed, the latch bolt can be moved freely — that’s how the door opens when you turn the knob or lever.
Here’s the critical part: when the door is closed and the deadlocking pin is NOT depressed (the pin is extended), the latch bolt is locked in place. It can’t be pushed back or shimmed. The deadlocking pin blocks the latch from retracting.
This is the anti-shim feature. A standard spring latch — without the deadlocking pin — can be pushed back with a thin piece of plastic (a credit card, a shim). A deadlatch with the deadlocking pin engaged cannot.
Why This Matters on a Storefront Door
Aluminum storefront doors typically use a cylindrical lock or a mortise lock with a latch bolt. When the business is open, the deadbolt is retracted and the door is held closed by the latch. The latch keeps the door from swinging open on its own (with the closer providing the closing force). But a standard spring latch can be shimmed — someone can slide a piece of plastic between the door and the frame, push the latch back, and open the door.
A deadlatch prevents this. The deadlocking pin contacts the strike when the door closes, locking the latch bolt in place. The door can still be opened from inside (turning the lever retracts both the latch and the pin), but it can’t be shimmed from outside.
The Failure Mode: Strike Misalignment
The deadlocking pin only works if it contacts the strike correctly. If the door has sagged, the frame has settled, or the strike is misaligned, the pin may not make contact. In that case, the deadlatch functions like a standard spring latch — it can be shimmed.
This is why strike alignment matters more on a deadlatch than on a deadbolt. A deadbolt doesn’t depend on the strike for its security — the bolt is mechanically locked in the extended position regardless of the strike. A deadlatch’s security depends on the pin contacting the strike. If the contact is off by even 1/8 inch, the pin may not engage, and the lock is bypassable.
Signs that the deadlocking pin isn’t engaging: the door can be pushed open without turning the lever, there’s visible play in the door when it’s “locked,” the latch bolt has scratch marks on the side from being shimmed, or the strike plate shows uneven wear on the pin contact area.
When to Use Each
Storefront door, business hours: Deadlatch engaged. The door is held closed by the latch, the closer keeps it shut, and the deadlocking pin prevents shimming. The door can be opened from inside without a key (lever turn) but can’t be shimmed from outside.
Storefront door, after hours: Deadbolt extended. Both the deadlatch and the deadbolt are engaged. The deadlatch provides the anti-shim function; the deadbolt provides the pick and force resistance.
Storefront door with exit device: The exit device replaces the cylindrical lock’s latch function. A Von Duprin 99 series exit device has a latch bolt that retracts when the bar is pushed. On the outside, keyed trim or electric trim controls entry. The exit device latch is not shim-able — it’s a heavier bolt with a different geometry than a cylindrical lock latch — but the principle is the same: the bolt has to engage the strike correctly to function.
Storefront door with electric strike: The electric strike replaces the strike plate. When the strike is locked, it holds the latch bolt. When unlocked, it releases the latch. The deadlocking pin still needs to contact the strike — if the electric strike doesn’t have the correct lip profile for the deadlocking pin, the anti-shim feature doesn’t work. This is a specific compatibility issue: not every electric strike works with every deadlatch.
What Pro Locksmith Does
Pro Locksmith LLC installs and services deadlatches, deadbolts, and exit device hardware on commercial aluminum storefront doors throughout Broward County and Miami-Dade, including Fort Lauderdale, Hollywood, Pembroke Pines, Davie, Pompano Beach, Coral Springs, and Miami. We verify strike alignment and deadlocking pin engagement on every installation. We use listed hardware from Schlage, Sargent, Von Duprin, and other approved manufacturers. Licensed and insured. Flat-rate pricing quoted up front. COI provided. Employees, not subcontractors.
If your storefront door’s latch can be pushed or shimmed, or the deadbolt isn’t engaging correctly, call Pro Locksmith LLC at (954) 406-8266.
Sources
- ANSI/BHMA A156.2, Bored and Preassembled Locks & Latches
- ANSI/BHMA A156.13, Mortise Locks
- ANSI/BHMA A156.3, Exit Devices
- NFPA 80, Standard for Fire Doors and Other Opening Protectives