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UL Listed Mortise Locks for Wood Doors vs Hollow Metal Doors

Publish Time: 2026-08-17     Origin: D&D HARDWARE

A UL listed mortise lock may be suitable for both wood doors and hollow metal doors, but that does not mean the two installations are identical.

The lock function, latchbolt operation, cylinder, lever trim, and basic case dimensions may remain the same. The differences usually appear around the lock:

  • How the mortise pocket is formed

  • What material supports the lock case

  • How the faceplate and trim are fastened

  • Whether internal reinforcement is required

  • How the strike is prepared in the frame

  • Whether intumescent or edge-sealing materials are required

  • Which modifications are permitted on the labeled door

  • Whether the complete door, frame, lock, and hardware combination maintains the required fire rating

The correct question is therefore not simply:

Is this a mortise lock for a wood door or a metal door?

It is:

Does the exact lock configuration fit the door preparation, fastening method, frame, fire-door listing, and installation conditions of this opening?

This guide compares the requirements that should be checked before specifying or installing a UL listed mortise lock in either door construction.

Quick Comparison: Wood Door vs Hollow Metal Door

Comparison point Wood door Hollow metal door
Lock case Installed in a routed or machined pocket in the lock edge Installed in a factory-formed or approved field-prepared pocket inside the steel door
Primary support Door stile, lock block, core construction, through-posts, and specified fasteners Internal steel reinforcement, lock tabs or clips, tapped holes, and machine screws
Edge preparation Pocket and faceplate recess must preserve the permitted door construction Cutout must align with reinforcement and standardized steel-door preparation
Faceplate fastening Commonly secured into the door edge using specified screws Commonly secured to reinforced and tapped steel preparation
Trim fastening Often uses through-bolts, posts, or chassis fasteners passing through the door Uses the lock manufacturer's through-bolts, posts, or machine-screw arrangement
Strike preparation Mortised into a wood or metal frame according to the frame construction Normally prepared in a reinforced steel frame and drilled or tapped as required
Fire-door concern Excessive routing can remove required stile, core, or protective material Unapproved cutting can remove reinforcement or alter the labeled steel construction
Additional fire protection Some listed wood-door constructions require intumescent material or a specific lock-pocket treatment Requirements depend on the steel-door listing; the same wood-door protection detail should not be assumed
Field modification Must remain within the door manufacturer's listing and permitted job-site preparation Must remain within the steel-door manufacturer's listing and applicable preparation rules
Typical coordination risk Incorrect pocket depth, insufficient remaining material, wrong fasteners, missing protective material Missing reinforcement, misaligned preparation, stripped threads, incompatible faceplate or strike
Does the UL mark on the lock approve the opening? No No

The lock cannot compensate for a door or frame that was prepared incorrectly.

Can the Same UL Listed Mortise Lock Be Used on Both Door Types?

In many cases, yes.

A commercial mortise lock manufacturer may offer the same lock case and function for:

  • Wood doors

  • Hollow metal doors

  • Fire-rated wood doors

  • Fire-rated hollow metal doors

  • Doors installed in wood frames

  • Doors installed in steel frames

However, the words "wood and metal door application" on a product page are only the beginning of the review.

The buyer still needs to confirm:

  1. The exact lock model and function

  2. Door thickness

  3. Lock backset

  4. Case dimensions

  5. Faceplate dimensions

  6. Trim preparation

  7. Cylinder or thumbturn arrangement

  8. Latchbolt and deadbolt projections

  9. Door handing and bevel

  10. Fastener type

  11. Required door reinforcement

  12. Strike dimensions and frame preparation

  13. Fire rating of the opening

  14. Lock listing scope

  15. Door manufacturer's approved hardware preparation

  16. Any required intumescent or edge-sealing components

Two doors can accept the same lock body while requiring different templates, fasteners, reinforcement, and installation procedures.

For background on the certification boundary, see what a UL listed mortise lock means for fire door compliance. The UL listing applies to a defined product and application; it does not independently approve every door into which the lock can physically fit.


What Actually Changes Between the Two Installations?

A mortise lock is concealed in a deep rectangular pocket in the door edge. That makes it more dependent on door construction than a small surface-mounted component.

The lock creates several interfaces:

  • The lock case fits inside the edge pocket.

  • The forend or faceplate sits flush with the door edge.

  • The lever spindle passes through the lock hubs.

  • Mounting posts or screws connect the inside and outside trim.

  • A cylinder, thumbturn, indicator, or emergency release engages the lock case.

  • The latchbolt and deadbolt project into the frame strike.

  • The strike transfers closing, latching, and attempted-entry loads into the frame.

Each interface must remain aligned.

Wood and hollow metal doors achieve that support differently. A wood door depends on its stile, core, lock block, and approved routing. A hollow metal door depends on formed steel edges, internal reinforcement, tapped preparations, and the position of the lock case within the door.

This construction difference affects both installation quality and fire-door compliance.

Mortise Lock Preparation in a Wood Door

The Pocket Is Cut into the Door Structure

In a wood door, the mortise pocket is normally machined into the lock edge. Separate face holes are then prepared for the spindle, cylinder, thumbturn, mounting posts, indicator, or other trim required by the function.

The preparation must match the exact lock template.

Important dimensions include:

  • Door thickness

  • Backset

  • Lock-case height, width, and depth

  • Faceplate length and width

  • Faceplate recess depth

  • Lever or knob centerline

  • Cylinder centerline

  • Thumbturn centerline

  • Through-bolt locations

  • Deadbolt and latchbolt positions

  • Distance between operating centers

  • Lock height above the finished floor

  • Relationship to the door bevel

The pocket should be large enough for the lock case and necessary wiring, when applicable, but it should not remove more material than the approved preparation permits.

An oversized cavity can reduce support around the lock, create loose fasteners, expose core material, or conflict with the door's fire-rated construction.

Door Core and Lock-Edge Construction Matter

The phrase "wood door" covers several constructions, including:

  • Solid lumber doors

  • Solid-core architectural wood doors

  • Particle-core doors

  • Structural composite lumber core doors

  • Mineral-core fire doors

  • Agrifiber or other engineered cores

  • Stave-core doors

  • Wood doors with proprietary fire-resistant cores

These constructions do not all respond to machining in the same way.

The mortise lock may be supported by:

  • A solid wood stile

  • A structural composite stile

  • A separate lock block

  • Reinforcing material incorporated around the lock edge

  • A proprietary core and edge system

  • Additional blocking specified by the door manufacturer

The installer should not assume that visible wood veneer indicates solid material throughout the lock area.

Before machining, confirm:

  1. Door manufacturer and model

  2. Door core

  3. Lock-edge construction

  4. Lock-block location and dimensions

  5. Maximum permitted pocket size

  6. Fire label and rating

  7. Approved lock type

  8. Required protection around the pocket

  9. Factory-preparation requirements

  10. Permitted job-site preparation

A pocket that fits into one architectural wood door may exceed the permitted preparation of another door with the same thickness and appearance.

Faceplate Fit Is Important

The lock faceplate should sit flush with the finished door edge.

If the faceplate stands proud:

  • It may rub the frame or strike.

  • The door may not close freely.

  • The latchbolt may not align with the strike.

  • The closing force needed to latch the door may increase.

If it is recessed too deeply:

  • The latchbolt may lose effective engagement.

  • The edge preparation may provide poor support.

  • The faceplate screws may be loaded unevenly.

  • The gap between the faceplate and strike can increase.

The recess also needs clean edges. Splintered veneer, crushed core material, and broken screw locations can compromise both appearance and fastening quality.

Fasteners Must Match the Door Construction

Do not replace the supplied fasteners with whichever screws are available on site.

Depending on the lock and trim design, a wood-door installation may use:

  • Edge screws for the lock faceplate

  • Through-posts connecting inside and outside trim

  • Through-bolts passing through prepared face holes

  • Cylinder retaining screws

  • Escutcheon or rose fasteners

  • Reinforced mounting plates

  • Manufacturer-specific screws for the door construction

Screw length and diameter matter. A screw that is too short may not develop adequate holding strength. A screw that is too long may interfere with the lock case, spindle, cylinder, wiring, or internal mechanism.

Repeatedly removing and reinstalling edge screws can also weaken wood-based material. If the installation does not align correctly, identify and correct the preparation error instead of enlarging screw holes to force the components into position.

 

Mortise Lock Preparation in a Hollow Metal Door

The Door Requires an Internal Lock Preparation

A hollow metal door is not an empty steel shell into which any lock can be inserted.

A correctly prepared door normally includes features such as:

  • A formed lock-edge cutout

  • Internal lock reinforcement

  • Lock mounting tabs, clips, channels, or brackets

  • Drilled and tapped mounting holes

  • Function holes for the spindle, cylinder, thumbturn, and trim

  • A faceplate recess or edge arrangement compatible with the lock

  • Suitable clearance inside the door for the case

  • Internal protection from core material or insulation

  • An edge construction that positions the lock correctly

ANSI/SDI A250.14 provides standardized dimensional preparations for common hardware in steel doors and frames. ANSI/SDI A250.6 addresses recommended hardware reinforcement.

These standards support coordination, but the actual door and lock templates still control. A standard mortise preparation should not be assumed to fit every proprietary lock case, escutcheon, electrified function, or nonstandard trim option.

Reinforcement Provides the Fastening Base

The steel face sheet alone may not provide sufficient material for a heavy commercial mortise lock.

Internal reinforcement creates a suitable mounting base and helps resist:

  • Repeated lever operation

  • Door slamming

  • Latch and deadbolt loading

  • Pulling at the trim

  • Torque applied to the lever

  • Impact around the lock edge

  • Loosening of the lock faceplate

  • Movement of the lock case inside the door

Current Steel Door Institute guidance identifies reinforcement and tapped mounting preparation as essential elements of mortised-hardware installation. The preparation must provide adequate thread engagement and hold the lock case in its intended position.

If reinforcement is missing, incorrectly located, or too weak, the installer should not solve the problem by fastening the lock only to a thin door skin.

The appropriate response may involve:

  • Confirming whether the correct door was supplied

  • Obtaining an approved reinforcement kit

  • Consulting the door manufacturer

  • Using a specifically authorized through-bolted method

  • Replacing the door with the correct factory-prepared construction

Any solution for a labeled fire door must remain within the door manufacturer's listing and approved modification procedures.

Machine Screws and Tapped Holes Require Care

Mortise locks in reinforced steel doors commonly rely on machine screws installed into tapped reinforcement.

Installation problems include:

  • Cross-threading

  • Stripped threads

  • Oversized field-drilled holes

  • Incorrect screw diameter or thread

  • Screws that bottom out before clamping the faceplate

  • Missing screws

  • Substitution with sheet-metal screws

  • Misaligned reinforcement behind the cutout

  • Loose tabs that allow the lock case to move

The lock should slide into its prepared position without using mounting screws to pull a misaligned case into the door.

If the faceplate holes do not align with the tapped reinforcement, check the template, handing, case orientation, faceplate size, and door preparation. Forcing the screws can damage the threads and leave the lock unsupported.

Edge Seams and Door Bevel Affect Alignment

Hollow metal doors can use different edge constructions and seam locations. They may also have square, beveled, or otherwise formed lock edges.

The lock faceplate must be compatible with that geometry.

Verify:

  • Door thickness

  • Edge seam position

  • Bevel direction

  • Faceplate width

  • Faceplate curvature or flatness

  • Lock centerline

  • Distance from the door face to the case

  • Strike alignment after the door is hung

The backset should be measured from the correct reference surface, particularly on a beveled edge. Measuring from the wrong face of the door can shift the cylinder and lever preparation relative to the lock case.

The Frame and Strike Are Part of the Comparison

A correctly installed lock can still fail to latch if the strike preparation is wrong.

The strike must receive the latchbolt and, where provided, the deadbolt without forcing the door out of alignment.

Strike in a Wood Frame

A wood-frame preparation may require:

  • A mortised strike plate

  • Accurate latchbolt and deadbolt pockets

  • Suitable jamb material behind the strike

  • Screws of the specified size and length

  • Additional reinforcement where required

  • Alignment with the lock centerline

  • Clearance for full bolt projection

The installer should not deepen or enlarge the strike pocket indiscriminately. Excessive material removal can weaken the jamb and reduce screw holding strength.

If the opening is fire rated, confirm that the wood frame itself is listed for the required rating and that the strike preparation is within its approved construction.

Strike in a Hollow Metal Frame

A hollow metal frame normally uses:

  • A factory or approved field-prepared strike cutout

  • Internal strike reinforcement

  • Tapped mounting holes

  • A mortar or dust box where specified

  • Clearance for latchbolt and deadbolt projection

  • A strike lip suitable for the frame profile

  • Alignment with the lock centerline

The strike cannot be selected from latchbolt dimensions alone. Its overall size, mounting-hole spacing, lip length, pocket depth, and frame compatibility also matter.

A mortise-lock strike designed for one frame profile may not sit correctly on another.

Bolt Engagement Must Be Verified on the Hung Door

After installation, confirm:

  • The latchbolt enters the strike without binding.

  • The auxiliary deadlatch does not fall into the strike opening.

  • The deadbolt fully projects where the function includes one.

  • The door remains positively latched when closed.

  • The latch does not depend on excessive closer force.

  • The strike does not hold the door away from the stop.

  • The lock operates with the door both open and closed.

  • The door does not have to be lifted, pushed, or pulled to operate the key or thumbturn.

Poor strike alignment is often mistaken for a defective lock.

Fire-Rated Wood Doors and Hollow Metal Doors Are Assemblies

A UL listed mortise lock is one listed component. The fire rating belongs to the acceptable door assembly, not to the lock alone.

The assembly may include:

  • Door leaf

  • Door frame

  • Hinges or pivots

  • Mortise lock

  • Strike

  • Cylinder and trim

  • Door closer

  • Gasketing

  • Edge-sealing material

  • Astragal

  • Coordinator

  • Automatic or flush bolts

  • Glazing and light kit

  • Threshold

  • Fasteners

  • Installation clearances

The lock must support positive latching, but the complete opening must satisfy the required rating and installation conditions.

The Door Rating Does Not Come from the Lock

A mortise lock advertised as suitable for a three-hour application does not turn a wood or steel door into a three-hour fire door.

The achievable rating is limited by the acceptable combination of:

  • Wall opening

  • Door construction

  • Frame construction

  • Door and frame labels

  • Hardware listings

  • Opening size

  • Glazing

  • Door configuration

  • Installation details

  • Applicable code and authority requirements

A wood door and a hollow metal door fitted with the same lock may carry different door ratings because their door constructions and labeled applications differ.

The buyer should avoid creating a single "lock fire rating" field and assuming it controls the whole opening.

Positive Latching Is Essential

A swinging fire door normally needs to close and positively latch.

For a mortise lock, this requires coordination of:

  • Latchbolt projection

  • Strike depth

  • Door-to-frame clearance

  • Bevel

  • Door closer adjustment

  • Gasketing compression

  • Frame alignment

  • Door sag

  • Lock and strike mounting

  • Auxiliary deadlatch position

A UL listed lock cannot maintain the door in the latched position if the latchbolt never fully enters the strike.

Wood Doors May Require Additional Protective Details

Some positive-pressure wood fire-door constructions use intumescent material or other protective components around the door edge, lock preparation, frame, or perimeter.

Requirements vary by listing.

Do not automatically add an intumescent lock kit because the door is wood, and do not omit one because the lock itself is UL Listed. Confirm:

  • Door manufacturer

  • Door construction

  • Fire rating

  • Lock type and pocket size

  • Edge-sealing category

  • Required material location

  • Required thickness

  • Whether the material is factory installed

  • Whether field installation is permitted

  • Whether the proposed lock trim affects the detail

Adding an unapproved material can be as problematic as omitting a required one.

Hollow Metal Doors Need Listed Construction Too

Steel does not eliminate the need for listing coordination.

For a hollow metal fire door, verify:

  • Door label and rating

  • Door model and construction

  • Frame label

  • Lock reinforcement

  • Face-sheet and edge construction

  • Permitted mortise-lock preparation

  • Latchbolt projection

  • Door size

  • Pair or single-door application

  • Astragal or coordinator requirements

  • Installation clearances

  • Field-modification limitations

An unapproved cutout can affect a hollow metal door even when the remaining material is steel.

Factory Preparation vs Field Preparation

Factory preparation is usually the most controlled approach when the lock model is known before the door is manufactured.

The door manufacturer can coordinate:

  • Exact lock template

  • Lock centerline

  • Pocket dimensions

  • Faceplate

  • Reinforcement

  • Function holes

  • Cylinder and trim

  • Handing

  • Door bevel

  • Strike

  • Fire-door construction

  • Labels and production records

Field preparation may be possible in defined circumstances, but it should not be treated as unlimited permission to alter a labeled door.

Before Field-Preparing a Wood Fire Door

Confirm in writing:

  1. The door manufacturer permits the proposed preparation.

  2. The exact lock model is acceptable.

  3. The pocket dimensions are within the door's approved construction.

  4. The lock block or stile is suitable.

  5. The required template is available.

  6. Any intumescent or protective material is identified.

  7. The proposed tools and procedure will not damage the door.

  8. The preparation falls within permitted job-site work.

  9. Additional listing-agency authorization is not required.

  10. The label will remain valid and legible.

Before Field-Preparing a Hollow Metal Fire Door

Confirm:

  1. The door includes the required lock reinforcement.

  2. The reinforcement matches the lock faceplate and case.

  3. The door is intended for a mortise-lock preparation.

  4. The field cutout is allowed.

  5. Function holes can be prepared without removing reinforcement.

  6. The lock does not conflict with edge seams, core material, or internal components.

  7. Drilling and tapping requirements are defined.

  8. The strike preparation is compatible.

  9. The work complies with the door manufacturer's listing.

  10. Written authorization is obtained when the work exceeds permitted preparation.

Do not assume that field work is acceptable merely because a non-rated version of the door could be modified that way.

Dimensional Information Required Before Ordering

"Standard mortise lock preparation" is not enough for an international purchase order or project submittal.

Provide a complete dimension set.

Required information Why it matters
Door construction Determines preparation, support, fastening, and listing review
Fire-rated or non-rated Determines certification and modification requirements
Required fire rating Must be coordinated with the complete assembly
Door thickness Controls spindle, cylinder, trim, posts, and fasteners
Door width and height May affect the listed opening and hardware application
Handing and swing Affects latch orientation, function, trim, and installation
Lock-edge bevel Changes the preparation reference and faceplate relationship
Backset Locates lever, cylinder, and case relative to the door edge
Lock centerline Coordinates door and frame preparation
Faceplate size Must match the door-edge recess or steel preparation
Lock-case dimensions Determine required pocket size
Lever or knob center Controls face-hole location
Cylinder center Must align with the lock-case mechanism
Thumbturn or indicator center Required for privacy and deadbolt functions
Through-bolt locations Must match trim and avoid the lock case
Latchbolt projection Affects strike engagement and fire-door suitability
Deadbolt projection Affects strike depth and frame preparation
Strike dimensions Must match the frame profile and mounting preparation
Frame construction Determines strike fastening and reinforcement
Required protective material Necessary for applicable listed door constructions
Electrified options Add wiring, connectors, monitoring, and certification considerations

Request both the lock template and the door manufacturer's preparation sheet. Do not rely only on nominal dimensions in a catalog table.

Door Thickness Requires More Than a Range Check

A lock may be offered for a door-thickness range, but several components must be sized correctly within that range:

  • Spindle

  • Through-bolts

  • Mounting posts

  • Cylinder length

  • Cylinder collar

  • Thumbturn spindle

  • Escutcheon screws

  • Indicator assembly

  • Emergency-release components

  • Wiring connectors

A lock case that fits inside the door does not prove that the supplied trim package fits the door thickness.

This becomes especially important when comparing:

  • A nominal 1-3/4-inch commercial door

  • A 45 mm door

  • A 50 mm door

  • A 55 mm door

  • A door with applied protective plates

  • A door with thick decorative cladding

  • A door using escutcheon trim on both faces

State the finished door thickness, including any layer that affects trim assembly.

Door Handing and Bevel Must Be Confirmed Together

Some mortise lock latchbolts can be reversed, but that does not make every part of the lock non-handed.

Depending on the function, handing may affect:

  • Latchbolt orientation

  • Auxiliary deadlatch

  • Lever rotation

  • Inside and outside trim

  • Cylinder side

  • Thumbturn side

  • Indicator

  • Deadbolt

  • Electrified monitoring

  • Request-to-exit switch

  • Faceplate

  • Strike

The order should identify:

  • Left hand

  • Right hand

  • Left-hand reverse

  • Right-hand reverse

  • Door swing

  • Egress side

  • Secure side

  • Lock-edge bevel

Do not depend on job-site latch reversal to correct an incorrectly specified function or trim arrangement.

Does Door Material Change the Lock Function?

Normally, no.

Passage, entry, classroom, storeroom, privacy, dormitory, apartment, and deadbolt functions describe how the lock operates. They do not identify the door material.

For example, an F07 storeroom lock can be used in an appropriately prepared wood or hollow metal door if:

  • The exact model is suitable for that door construction.

  • The preparation is correct.

  • The lock's certification scope covers the required application.

  • The door assembly accepts the lock.

  • The outside and inside operation match the hardware schedule.

The function should be selected from the required access behavior, not from the door material. Readers comparing operating sequences can use the separate guide to UL listed mortise lock functions.

Does Door Material Change ANSI/BHMA Grade 1 Performance?

The Grade 1 designation belongs to the lock's tested mechanical performance under ANSI/BHMA A156.13. It is not a wood-door grade or a hollow-metal-door grade.

However, field performance still depends on the installation.

A Grade 1 lock can perform poorly if:

  • The wood-door pocket is oversized.

  • Edge screws are loose.

  • The hollow metal door lacks reinforcement.

  • Machine-screw threads are damaged.

  • The spindle is too short.

  • The cylinder is incorrectly sized.

  • The strike is misaligned.

  • The door sags.

  • The closer slams the door.

  • The latchbolt does not fully engage.

The performance claim does not eliminate the need for a stable mounting structure.

Replacement Projects Require Extra Measurement

Replacing a mortise lock is more difficult than ordering hardware for a new door because existing preparations may not follow the new lock template.

Measure the actual opening instead of identifying the old lock only by brand or function.

Record:

  • Existing door material

  • Door thickness

  • Door edge and bevel

  • Lock-case pocket height, width, and depth

  • Faceplate dimensions

  • Backset

  • Lever or knob center

  • Cylinder center

  • Distance between centers

  • Through-bolt pattern

  • Existing strike dimensions

  • Strike-lip length

  • Latchbolt and deadbolt positions

  • Door handing

  • Frame profile

  • Existing reinforcement

  • Fire label information

  • Previous field modifications

  • Condition of screw holes and tapped threads

A filler plate or adapter may conceal an old cutout on a non-rated opening, but it should not be assumed acceptable for a labeled fire door. Confirm the approved repair or retrofit method before altering the door.

Common Selection and Installation Mistakes

Assuming "For Wood and Metal Doors" Is Complete Approval

It is only a general application statement. The exact door construction, listing, preparation, rating, and fasteners still require confirmation.

Using the Wood-Door Template on a Hollow Metal Door

The lock centers may match, but the steel-door preparation also needs correctly located reinforcement, tapped mounting points, and a compatible faceplate cutout.

Using the Hollow-Metal Preparation as a Routing Guide for Wood

A dimensional steel-door preparation does not identify the wood door's permitted pocket size, lock block, core, or required protective material.

Ordering the Door Before Selecting the Lock

This can result in a generic preparation that does not match the final faceplate, trim, cylinder, function holes, or electrified options.

Preparing a Fire Door from a Catalog Drawing Alone

The lock drawing explains what the lock needs. It does not independently establish what modifications the labeled door permits.

Assuming All 1-3/4-Inch Doors Use the Same Preparation

Door thickness is only one dimension. Backset, lock case, faceplate, trim, bevel, function, and door construction may still differ.

Omitting Hollow Metal Reinforcement

A thin face sheet should not be treated as the complete support for a heavy commercial mortise lock.

Enlarging a Wood-Door Pocket to Make Installation Easier

Excess clearance allows the case to move and can remove material required by the door construction.

Pulling a Misaligned Lock into Position with Screws

Mounting screws should secure the lock, not deform the case, reinforcement, faceplate, or door edge.

Using the Wrong Strike

A visually similar strike may have a different lip, pocket, bolt opening, hole spacing, or frame application.

Assuming the Lock's UL Mark Covers the Door

The door, frame, hardware, rating, and installation remain separate parts of the assembly review.

Applying Intumescent Material Without Checking the Listing

Some wood-door constructions require specific material; others use different protection details. An improvised solution is not reliable evidence of compliance.

Treating a Field Modification as a Minor Carpentry or Metalworking Task

On a labeled fire door, the listing and permitted preparation control the work—not merely whether the installer can physically make the cut.


Recommended Installation Sequence

A controlled sequence helps identify door-related problems before the lock is damaged.

1. Verify the opening

Check:

  • Door and frame labels

  • Door material and construction

  • Required fire rating

  • Door swing and handing

  • Door thickness

  • Frame profile

  • Hardware schedule

  • Lock function

2. Verify the proposed lock

Confirm:

  • Manufacturer

  • Exact model

  • Function

  • UL certification scope

  • Latchbolt and deadbolt

  • Backset

  • Faceplate

  • Trim

  • Cylinder

  • Fasteners

  • Door-thickness range

  • Mechanical or electrified construction

3. Compare the templates

Compare the lock template with:

  • Wood-door preparation sheet, or

  • Hollow-metal door and reinforcement preparation

Also compare the strike with the frame preparation.

4. Inspect the door preparation

For a wood door, inspect pocket size, remaining edge material, lock block, faceplate recess, and protective components.

For a hollow metal door, inspect reinforcement, mounting tabs, tapped holes, cutout dimensions, edge seams, and internal clearance.

5. Test-fit without forcing

The case should enter the pocket in the correct orientation. Confirm that the faceplate sits flush and that the spindle, cylinder, and trim holes align.

6. Install the case with the specified fasteners

Do not substitute screw types or use the screws to correct a misaligned preparation.

7. Install the cylinder and trim

Verify cylinder projection, cam engagement, lever return, spindle length, mounting-post alignment, and inside/outside orientation.

8. Install and align the strike

Make sure the latchbolt and deadbolt enter their intended pockets without binding.

9. Test every operating state

Test:

  • Door open and closed

  • Key operation

  • Inside lever

  • Outside lever

  • Thumbturn

  • Deadbolt

  • Auxiliary deadlatch

  • Emergency release

  • Indicator

  • Electrified control, if applicable

  • Retained locked or unlocked state

  • Positive latching after closing

10. Complete fire-door inspection checks

Confirm labels, clearances, self-closing, positive latching, prohibited modifications, missing fasteners, auxiliary hardware, and the overall condition of the assembly.

Selecting D&D Mortise Locks for Wood and Hollow Metal Doors

D&D HARDWARE presents its commercial ANSI mortise locks for both wooden and metal door applications. The range includes passage, entry, classroom, storeroom, privacy, dormitory, deadbolt, and other functions.

Published product information for several models identifies common characteristics such as:

  • Stainless steel lock cases and components

  • 2-3/4-inch or approximately 70 mm backset

  • 3/4-inch or approximately 19 mm latchbolt projection

  • Standard door-thickness ranges such as 45–55 mm on identified models

  • Left-hand and right-hand applications

  • Wood-door and metal-door use

  • UL and ANSI/BHMA performance claims

These figures should not be transferred automatically from one model to another.

When evaluating the D&D UL-listed ANSI mortise lock range, provide the complete opening information and request confirmation of:

  1. Exact D&D model and function

  2. Mechanical or electrified configuration

  3. Door material and construction

  4. Fire rating

  5. Door thickness

  6. Handing and bevel

  7. Backset

  8. Lock-case and faceplate dimensions

  9. Lever, rose, or escutcheon preparation

  10. Cylinder or privacy trim

  11. Wood-door or hollow-metal fasteners

  12. Required steel reinforcement

  13. Strike model and frame preparation

  14. Latchbolt and deadbolt projections

  15. Applicable UL certification record

  16. ANSI/BHMA test evidence

  17. Lock and door templates

  18. Installation instructions

  19. Required intumescent or edge-sealing details

  20. Compatibility with the complete fire-door assembly

The purpose of this review is not to create separate "wood-door" and "metal-door" versions where the same lock can serve both. It is to ensure that the delivered lock package includes the correct components and preparation information for the actual opening.

Conclusion

UL listed mortise locks for wood and hollow metal doors are not necessarily different lock products. In many projects, the same lock case can serve both door types.

What changes is the structure supporting the lock.

A wood door relies on its lock edge, stile, lock block, core, approved pocket, and specified fasteners. A hollow metal door relies on its formed edge, internal reinforcement, tapped mounting points, and coordinated steel-door preparation. The frame and strike must also match the selected opening.

For fire-rated applications, physical fit is not enough. The exact lock model, door construction, frame, preparation, fasteners, protective materials, rating, and installation must remain within the applicable certified assembly conditions.

Before ordering, establish a traceable relationship among:

  • Scheduled opening

  • Door and frame construction

  • Lock function

  • Exact lock model

  • Lock template

  • Door preparation

  • Reinforcement or lock block

  • Strike

  • UL listing scope

  • Installation instructions

  • Delivered product markings

That coordination determines whether a mortise lock is genuinely suitable for a wood or hollow metal door—not the wording of the product title alone.

Frequently Asked Questions

Are mortise locks different for wood doors and hollow metal doors?

The same lock case can often be used in both. The main differences are the door preparation, reinforcement, fastening method, strike installation, and fire-door compatibility.

Can any UL listed mortise lock be installed in a wood fire door?

No. The exact lock must be suitable for the required application, and the wood door's listing must permit the lock type and preparation. Pocket dimensions and any required protective material must also be confirmed.

Can a mortise lock be installed directly into an unreinforced hollow metal door?

A commercial hollow metal door normally requires an appropriate reinforced lock preparation. Do not rely only on a thin steel face sheet unless the door and lock manufacturers specifically authorize another fastening method.

Is a wood door easier to prepare for a mortise lock?

Wood is easier to machine, but that does not make the preparation less critical. An oversized or incorrectly located pocket can weaken the mounting area or conflict with a fire-door construction.

Should mortise locks be factory prepared?

Factory preparation is generally preferable when the exact hardware is known, especially for labeled doors. It improves coordination of the pocket, reinforcement, function holes, trim, strike, and listing requirements.

Does a hollow metal door always have a standard mortise-lock preparation?

No. It may be factory prepared for a particular standard or manufacturer template, prepared only for another lock type, or supplied without the required function holes. Verify the actual preparation and reinforcement.

Do wood doors need intumescent material around a mortise lock?

Some listed fire-door constructions do; others use different protective details. Follow the door manufacturer's listing and preparation instructions rather than making a general assumption.

Is the strike the same for wood and hollow metal frames?

Not necessarily. Strike size, lip, mounting screws, reinforcement, and preparation can differ between wood and steel frames.

Does ANSI/BHMA Grade 1 mean the lock fits both door types?

No. Grade 1 addresses the lock's mechanical performance. Door fit and fire-door compatibility must be verified separately.

Can a reversible latch solve incorrect handing?

It may correct latchbolt orientation on certain models, but it does not necessarily correct the complete function, trim, cylinder side, indicator, deadbolt, monitoring, or bevel relationship.

Can installers enlarge the preparation of a labeled door?

Only within the door manufacturer's permitted preparation and applicable listing requirements. More extensive modifications may require written authorization or field evaluation.

Does the UL mark on the lock prove that the completed door is compliant?

No. The door, frame, hinges, closer, lock, strike, gasketing, installation, and other components must form an acceptable assembly.

What should be checked first when a new mortise lock does not fit?

Compare the exact lock template with the door preparation. Check door thickness, backset, faceplate, case dimensions, trim holes, handing, bevel, reinforcement, and whether the correct lock model was supplied.

Contact us Now:

Contact: David Jian

Mob:0086-139 2903 7292

Email: David@dndhardware.com, sales@dndhardware.com,

Contact: Jobby Zhang

Mob:0086-137 2599 9617

Email: jobby@dndhardware.com


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ADD:12th Floor, Building 2, No.898, KeChuang Technical Zone, Jiangmen Avenue, Pengjiang District, Jiangmen City, Guangdong, China (Postcode:529000)

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Tel: +86-750-3856396

Fax: +86-750-3856395


Contact Info

:+86-139 2903 7292   David Jian

:  +86-750- 3856396

 : sales@dndhardware.com
 
: +86-139 2903 7292
 
 : +86-139 2903 7292

:  12th Floor, Building 2, No.898, KeChuang Technical Zone,
Jiangmen Avenue, Pengjiang District, Jiangmen City, Guangdong, China
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