How to Identify Your Storefront Door Lock: Deadlock, Deadlatch, or Bottom Rail

Identify a storefront lock in four checks: where the lock body sits, how the bolt or latch moves, what hardware appears on the inside, and what model markings remain on the old parts. A rigid hookbolt or straight deadbolt suggests a deadlock; a spring-loaded latchbolt with a strike and interior push paddle suggests a deadlatch; a lock housed in the glass door’s lower rail suggests a bottom-rail lock. Treat the result as a likely category until measurements confirm it.

Quick Comparison: Deadlock vs. Deadlatch vs. Bottom-Rail Lock

The outside keypad or cylinder is not enough to classify the lock. Deadlocks and deadlatches can occupy a similar position in a narrow aluminum stile, so the bolt or latch action and interior hardware matter.

The Four-Check Identification Method

Check 1: Where Is the Lock Body?

Look at the door edge and the bottom rail—not only the outside trim.

• A lock body mortised into a narrow vertical stile may be a deadlock or a deadlatch.
• A lock body built into the lower rail of a commercial glass door belongs to the bottom-rail category.
• A residential cylindrical knob or tubular deadbolt is outside the three storefront categories covered by this guide.

Location creates the first branch, but it does not separate a deadlock from a deadlatch by itself.

Check 2: What Moves—A Rigid Bolt or a Spring-Loaded Latch?

Observe the locking part without forcing or bypassing the door hardware.

• A straight deadbolt projects as a rigid bolt.
• A hookbolt has a hook-shaped locking end and is commonly used in sliding narrow-stile applications.
• A deadlatch latchbolt is spring-loaded and works with a strike.
• A bottom-rail lock operates at the rail and threshold or floor interface rather than from the vertical door edge.

The terms sound similar, but a deadbolt and a deadlatch are not the same mechanism.

Check 3: What Is on the Inside of the Door?

Inside hardware adds another piece of evidence.

• A knob or thumb turn may support a deadlock identification.
• A push paddle combined with a spring-loaded latchbolt and matching strike strongly supports a deadlatch identification.
• Hardware operating from the bottom rail supports a bottom-rail identification.

A push paddle is operating trim, not the lock body itself. It should be evaluated together with the latchbolt and strike.

Check 4: What Does the Old Label or Model Marking Say?

Photograph any readable brand, model number, backset marking, faceplate code, or cylinder label. A marking can help choose the correct technical drawing or product family, but it is not a fit guarantee. Parts may have been changed over time, and similar model names can have different backsets, faceplates, bolts, or site preparations.

Use model markings as evidence to verify—not as permission to skip measurements.

How to Recognize a Narrow-Stile Deadlock

A narrow-stile storefront deadlock is typically mortised into the vertical aluminum stile. At the door edge, look for a faceplate and a rigid locking bolt:

• A straight deadbolt projects straight into the prepared jamb or strike area.
• A hookbolt projects and hooks into its receiving hardware; this form is commonly associated with sliding-door applications.
• The inside may have a knob or thumb turn that projects and retracts the bolt.

Unlike a spring latch, the deadlock bolt does not identify itself by compressing as the door closes. The exact bolt type, backset, faceplate, strike, and door preparation still need to be recorded.

Within the EASILOK range, a likely deadlock category leads to SK1850, SK1850S(sfic), or SM1850 for further investigation. It does not yet prove that one of those models fits.

How to Recognize a Deadlatch with a Push Paddle

A storefront deadlatch can also be mortised into a narrow vertical stile, so location alone does not separate it from a deadlock. Look for the combined evidence:

1. A spring-loaded latchbolt at the door edge.
2. A matching strike on the frame.
3. An interior push paddle or related latch operator.
4. A latch that retracts when the correct interior operator is used.

Adams Rite describes its 4510 deadlatch as using a spring-loaded latchbolt that can be retracted by a handle or paddle. For EASILOK selection, the SK4510 and SK4510S(sfic) family follows the deadlatch-with-push-paddle path, subject to backset, door thickness, handing, strike, frame, holes, and current product configuration.

Do not call the push paddle the lock body. Do not assume that every door with a paddle uses the same deadlatch.

How to Recognize a Bottom-Rail Lock

A bottom-rail lock sits low in the door instead of in the vertical stile. On a commercial glass door, inspect:

• The lower door rail and the area where the lock body is housed.
• The threshold or floor receiver that works with the lock.
• The old lock’s face, access points, and removal path.
• Any visible marking associated with CRL 777S, FHC R777, ILCO BRL, or another rail-lock configuration.

EASILOK SK777 and SK777S(sfic) belong to this bottom-rail path. The reference models help with initial identification, but they do not show that all rail dimensions or glass-door preparations are identical.

Measure the rail, not just the glass. A catalog thickness value cannot be treated as the glass thickness or as a universal fit rule. Threshold clearance and the path for removing the old lock can also determine whether a replacement is practical.

What Photos Can—and Cannot—Confirm

Photos can help answer:

• Is the lock probably in the deadlock, deadlatch, or bottom-rail category?
• Is the visible bolt a hookbolt, straight deadbolt, or spring-loaded latchbolt?
• Is a push paddle, knob, thumb turn, strike, or floor receiver present?
• Is there a readable model marking that points to the correct documentation?

Photos alone usually cannot confirm:

• The exact backset or door thickness without a physical reference.
• Hidden holes, internal modifications, or complete lock-body dimensions.
• The exact SKU required.
• Whether an SFIC core matches an existing keyway or master-key system.
• Whether the replacement will be drill-free at that site.
• Whether the door complies with site-specific building, fire, accessibility, lease, or egress requirements.

The safe output from a photo review is “likely category” or “candidate family—verify before ordering,” not “confirmed fit.”

Six Photos to Take Before Ordering

Take the photos in good light, hold the camera square to the subject, and avoid cropping out the surrounding door hardware.

1. Outside view: the exterior operator and enough of the door stile to show its position.
2. Inside view: the knob, thumb turn, push paddle, or bottom-rail operator.
3. Door-edge or rail view: the faceplate and lock-body position; include a readable model marking when available.
4. Bolt, latch, and receiver view: show the hookbolt, straight deadbolt, or latchbolt together with the frame strike, threshold, or floor receiver.
5. Full-door view: show whether the door swings or slides, its handing, and the surrounding frame.
6. Ruler-based measurement view: show the measurement and its start and end reference points. For a bottom-rail lock, include the rail, threshold, and available clearance in this measurement set.

Also send close-up photos of every readable label. For every dimension, include a physical ruler or tape, keep the start and end reference points visible, and have the measurement reviewed by a person. A screenshot or an unscaled photo cannot establish an actual backset.

Measurements Required After Identification

Once you have a likely category, complete the fit check.

For a Narrow-Stile Deadlock or Deadlatch

Record:

• Backset using the correct existing-lock reference point.
• Door thickness.
• Faceplate shape and dimensions.
• Hookbolt, straight deadbolt, or latchbolt configuration.
• Existing holes and trim footprint.
• Frame and strike configuration.
• Interior hardware and door handing.
• For an SFIC option, the core specification, keyway, pin count, and keying requirement.

The current EASILOK catalog includes 31/32-inch, 1-1/8-inch, and 1-1/2-inch backset options for the narrow-stile deadlock and deadlatch families and lists a 1-3/8-inch to 1-3/4-inch door-thickness range. A matching number is only one part of the fit decision.

For a Bottom-Rail Lock

Record:

• Rail construction and dimensions.
• Threshold or floor-receiver position and clearance.
• Old-lock dimensions and access points.
• How the old lock can be removed.
• Cylinder or SFIC requirement when applicable.

Do not substitute glass thickness for rail measurements.

Map the Likely Category to an EASILOK Family

Use the lock-body-first EASILOK selection guide after identifying the category. Then use the storefront lock measurement guide to document the dimensions.

When the Lock Type Is Still Unclear

Do not choose a product by exterior appearance alone. Send EASILOK support the full photo set, model markings, and ruler-based measurements. If the lock body is hidden, the preparation has been modified, the door does not operate normally, or life-safety hardware is involved, ask a qualified locksmith or door professional to inspect the opening.

The goal is not to force every door into one of three product families. The goal is to rule out the wrong family early and gather enough evidence for a responsible fit decision.

Frequently Asked Questions

Are EASILOK deadlocks, deadlatches, and bottom-rail locks interchangeable?

No. Deadlocks, deadlatches, and bottom-rail locks are different lock-body categories and are not interchangeable. Each depends on its own bolt or latch, strike or receiver, interior hardware, door preparation, and measurements. First identify the existing category, then verify the exact configuration before comparing EASILOK models.

How can I tell a storefront deadlock from a deadlatch or bottom-rail lock?

Start with the lock location, then check the bolt or latch, the inside hardware, and any old model marking. A rigid door-edge deadbolt or hookbolt suggests a deadlock; a spring-loaded latchbolt with a strike and interior paddle suggests a deadlatch; a lock housed in the glass-door lower rail suggests a bottom-rail lock.

What photos should I send before choosing a replacement lock?

Send six clear views: outside, inside, door edge or rail with any model label, bolt or latch with its strike or floor receiver, the full door and handing, and a ruler-based measurement. For a bottom-rail lock, include the rail, threshold, and clearance. Photos support initial identification only; field conditions may still require professional verification.

Sources and Verification

• Adams Rite MS1850S Series Deadlocks
• Adams Rite 4510 Standard Duty Deadlatch
• CRL 777S Door Rail Floor Lock
• EASILOK storefront deadlock collection
• EASILOK storefront deadlatch collection
• EASILOK bottom-rail lock collection

Identification and product-family statements were checked against the current EASILOK catalog and product documentation. Last reviewed: July 23, 2026.

Identify First, Then Verify the Fit

Use the four checks and photo list to determine the likely lock-body category. Next, follow the EASILOK selection guide, collect ruler-based measurements, and contact EASILOK support or a qualified door professional if the evidence does not lead to one clear category.