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
Narrow Stile Doors Change the Hardware Options
Most aluminum storefront doors in South Florida plazas are narrow stile doors, meaning the vertical frame members around the glass are only a few inches wide. That narrow stile does not have room for a standard cylindrical deadbolt or a full size mortise lock. Instead, these doors use locks built specifically for narrow stile aluminum, where the lock body fits inside the stile and a threaded mortise cylinder operates it from the outside.
This matters because the deadbolt on a storefront door is not the same round bolt you see on a house. It is typically a hook bolt or swing bolt that pivots out of the lock body into the frame. A well known example is the Adams Rite MS1850 style deadlock, which has been used on aluminum storefronts for decades. The bolt swings out in an arc and hooks behind the strike, which makes it resistant to the door being pried away from the frame. A straight bolt in a narrow stile can sometimes be defeated by spreading the frame enough to clear the bolt. A hook bolt resists that spreading.
Bolt Throw and Why Length Matters
The distance a bolt extends out of the lock body is called its throw. Storefront frames often have a noticeable gap between the door and the jamb, and the frame itself can flex. A bolt with a short throw might only just reach into the strike. If the frame is pried even slightly, the bolt slips out. When evaluating a storefront deadlock, look at how far the bolt actually engages the strike with the door closed, not just how far it extends when the door is open. A bolt that barely catches is not doing much.
Deadlatches on Storefronts: Paddles and Push Pulls
For daytime operation, narrow stile storefronts often use a deadlatch operated by a paddle handle or a lever, rather than a knob. The Adams Rite 4900 series is a common deadlatch on these doors, paired with paddle or lever trim. The deadlocking plunger discussed above sits alongside the latch in the same way. When the door is closed correctly, the plunger is held in by the strike and the latch is deadlocked against shimming from outside.
Push pull doors with no latch at all are a different situation. Many retail entries simply have a pull handle outside and a push bar or plate inside, held shut during business hours by the closer alone, and locked at night with the deadlock. These doors have no deadlatch protection during the day because they have no latch. That is usually acceptable for an open retail entry where staff are present, but it means the deadbolt has to be thrown every night without exception.
Cylinder Guards and Pry Protection
The mortise cylinder on a storefront door sticks out from the face of the door, and that exposed cylinder is a target. Twisting it with pliers or a wrench can break the set screw or pull the cylinder right out of the lock. Cylinder guard rings, which are spinning or hardened collars that surround the cylinder, make it much harder to grip. A security cylinder with hardened inserts adds drill resistance.
The gap between a storefront door and its frame is another weak point. Pry attempts usually start there. A latch guard or astragal that covers the gap at the lock location keeps tools from reaching the bolt or latch. On pairs of doors, the center meeting stile is where most attacks focus, so a solid astragal and correctly adjusted flush bolts on the inactive leaf are as important as the lock itself.
Double Cylinder Deadlocks and Exit Rules
Many storefront deadlocks are keyed on both sides, meaning a key is needed from inside to unlock the door. Business owners like this because a burglar who breaks the glass cannot simply reach in and turn a thumbturn. However, a door that requires a key to open from inside can trap people if it is locked while the building is occupied.
Building and fire codes address this directly. In some occupancies they allow key-operated locking on the main entrance only under specific conditions, such as the door being readily recognizable as locked, a sign stating that the door must remain unlocked while the building is occupied, and the lock being used only when the building is empty. Other doors, and other occupancies, do not allow it at all. The rules depend on the type of business and the door in question, and the local fire marshal has the final word. If you are considering a double cylinder deadlock, or you already have one, we can tell you what options exist and help you confirm what is permitted for your space.
When Both Hardware Pieces Fight Each Other
A common problem on storefronts is a deadlatch and a deadbolt that were installed at different times by different people. The deadlatch strike and the deadbolt strike are separate pieces cut into the frame. If one is adjusted and the other is not, the door may latch but not bolt, or bolt only when someone pushes hard on it. Another conflict happens when an exit device is added to a door that already has a deadlock. If the deadlock is thrown while the exit device is expected to provide one-motion egress, the push bar no longer opens the door. This two motion situation, where someone must first unlock the deadbolt and then push the bar, is a problem on doors required for exiting.
The fix is to design the door as one system. On a door with an exit device, the exit device usually becomes the only locking hardware, sometimes with a key cylinder dogging the bar during business hours. On a door with a deadlatch and a deadlock, both strikes are adjusted together so that each engages fully when the door closes normally.
Mortise Locks on Wider Stile Doors
Not every commercial storefront is narrow stile. Wide stile aluminum doors, hollow metal doors and wood doors on older buildings often use a full size mortise lock, which fits a much larger lock body into a pocket cut into the door edge. A mortise lock can combine a deadlatch and a deadbolt in one case, sharing a single strike, and a single turn of the key or thumbturn can throw the bolt. Many mortise locks also retract the deadbolt and the latch together when the inside lever is turned, which provides one motion egress while still giving the door a true deadbolt when locked.
This combined design removes some of the alignment problems that come from two separate locks on one door, because the latch and bolt are fixed relative to each other in the same case. The tradeoff is that the door has to be thick and wide enough to accept the lock body, which rules out most narrow stile glass doors.
Key Control on the Storefront Cylinder
The outside cylinder on a storefront is the one lock in the building that every opening employee needs. That means it is also the key most likely to be copied, lent out or lost. A restricted keyway cylinder in the storefront lock, where duplicates can only be cut with authorization, keeps the front door key from multiplying. Because storefront locks use standard threaded mortise cylinders, upgrading usually means swapping only the cylinder, not the lock. The same cylinder can be keyed into a master system so managers carry one key for the front door, the back door and the office.
How to Check Your Own Storefront Door
Business owners can do a quick check without tools:
- With the store open and the deadbolt retracted, close the door gently and try to pull it open from outside without using the handle. It should not move. If it does, the latch is not engaging.
- Look at the latch through the gap between door and frame. The small deadlocking plunger should be pressed in by the strike, not sticking out into the strike opening.
- At closing, throw the deadbolt and watch it enter the strike. It should move smoothly without the door being pushed or lifted.
- Push and pull the locked door firmly. A small amount of movement is normal. A door that rattles noticeably or lets you see the bolt shift is telling you the bolt is not fully engaged.
- Check the outside cylinder. It should not turn in the door when gripped by hand. If it does, the set screw is loose.
Closers and Latching Go Together
A deadlatch can only deadlock if the door actually closes all the way. The door closer is what brings it there. If the closer has lost its latch speed adjustment, the door may drift to within an inch of the frame and stop, leaving the latch resting against the strike lip instead of seated in it. The deadlocking plunger never engages, and the door can be pulled open from outside. When a storefront latch problem appears, checking that the closer brings the door fully home at a controlled speed is part of the diagnosis.
After a Break-In Attempt
When a storefront has been pried, the lock may still work, but the door and frame have usually been bent. Aluminum does not spring back completely. A bent frame changes where the strike sits, which can leave the deadlatch plunger unable to engage and the deadbolt catching only the edge of its strike. We check alignment across the whole opening after any forced entry attempt, straighten or replace damaged parts, and reset both strikes so the door is returned to full security rather than just being made to close again.
Keeping Storefront Locks Working in Salt Air
Coastal storefronts in Fort Lauderdale, Hollywood, Pompano Beach and along the beaches corrode faster than inland ones. Latches get sluggish, the deadlocking plunger sticks in or out, and cylinders become hard to turn. A sticky plunger is a security problem, since a plunger stuck out will not deadlock and a plunger stuck in can prevent the latch from working at all. Periodic cleaning and lubrication with products meant for locks keeps these parts moving. Avoid heavy oils that attract sand and grit.
Pro Locksmith services storefront locks for retail and commercial clients across Broward County, north through Boca Raton and Delray Beach to West Palm Beach, and south through Aventura, North Miami, Coral Gables and Coconut Grove.