Glossary of Terms For Steel Doors and Frames

MDM Security Doors

Glossary of Terms For Steel Doors and Frames

Definitions of some terms commonly used in connection with hollow metal doors.


Ironmongery device (eg: panic or push bar) which both unlocks the door set and opens it in one positive action.

Active Door

In a pair of doors, the one in which the latching device is installed. The leaf that opens and closes first.

Actual Door Size

The exact width and height of the door leaf itself.

Anti-Jemmy Strip

Folded steel the full length of the leading edge of the door leaf to protect against attack of the lock.


Acceptable to the Authority Having Jurisdiction.


An individual who is registered or licensed to practice their respective design profession as defined by the statutory requirements of the professional registration laws of the state of jurisdiction in which the project is to be constructed. A representative of the building owner.


The dimension from a cutout or datum line for a hardware preparation from a defined datum on a door or frame.

Flush Bolt Backset

The dimension from the vertical centerline of the leading edge of a door to the centerline of the bolt.

Hinge Backset

On a door, the dimension from the stop face, or narrow side, to the edge of the hinge cutout. On a frame, the distance from the stop to the edge of the hinge cutout.

Lock Backset

The dimension from the vertical centerline of the leading edge of a door to the centerline of the lock cylinder, measured horizontally and parallel to the door face.

Strike Backset

On a door frame, the dimension from the stop to the edge of the strike cutout.


A metal bar which, when actuated, is projected (thrown) either horizontally or vertically into a retaining member, such as a strike plate, to prevent a door from operating or opening.


An insurance standard for security door locks.


Round plastic plugs inserted in door frame to conceal fixing holes

Butt Hinge

A hinge with rectangular leaves, usually of the same size, and multiple bearing contacts.

Butt Joint

Intersecting members, which are not mitered.

Butted Frame

A frame which fits against a wall rather than around it.


A term used to define a distance between two surfaces.


The area of the floor below a door.

Clear Opening

The nominal clear opening width when the security door is in the fully open position.


A device or mechanism to control the closing of a hinged door.

Closer Reinforcement

A metal plate or channel designed to provide additional strength to a door or frame for the attachment of a door closer.


The interior construction of a hollow metal door.

Cover Plate

A flat piece of metal used at corner conditions to cover abutting frame members and the exposed face of either a floor closer not covered by the threshold or a closer mounted in the head of a door frame.


The cylindrical mechanism, which receives the key, used to operate a lock. The sub-assembly of a lock contains the cylinder core, tumbler mechanism, and the key way. There are two basic types:

Mortise Type

having a threaded surface which screws directly into a lock case, with a cam engaging the lock mechanism.

Rim Type

mounted on the surface of the door independently of lock, usually by screws from the reverse side, and engaging with the lock mechanism by means of a tail-piece or metal extension.


A double cylinder lock has a key actuated cylinder on both the exterior and interior of the door.

Cylinder Cam

The flat metal plate at the end of a mortise type cylinder, serving to actuate the lock mechanism.

DDA Compliant Threshold

A floor mounted threshold strip, less than 15mm in height, required to comply with the Disability Discrimination Act 1995. Although now replaced by the Equality Act 2010, the new act incorporates essential requirements of the old act including the provision of accessible low profile threshold strips in key locations.

DDA Regulations

Disability Discrimination Act as applies to security doors/entrances.

Deadbolt (of a lock)

A lock bolt having no spring action or bevel, and which is operated by a key or a thumb turn.


A lock in which a bolt is moved by means of a key or thumb turn, and which is positively held in its projected position. A lock equipped with a deadbolt only.

Deadlock and Latch

A hardware item containing both a deadbolt and a latchbolt.


A linear measurement such as length, width or thickness.

Door Edge

The four surfaces of the door that are normally perpendicular to the door face.

Door Face

The surface of the door viewed in elevation.

Door Frame

An assembly of members surrounding and supporting a door or doors, and perhaps also one or more transom lights and/or sidelights.

Door Opening

The area in a frame product into which a door or doors are installed.

Door Schedule

The listing of all door openings on the project by Architect’s mark number, including a description of each door opening. The schedule is normally found in the contract plans or in the specification portion of the contract documents.

The portion of the contract documents that provides a listing of all door openings and descriptions.


A molding designed to prevent rainwater from running down the face of a door or window, or to protect the bottom of a window or door from leakage.

Dog Bolts

Steel bolts, fitted to the door leaf edge, that engage the security door into the frame jamb on the hinge side.

Door Edge Clearance

The clear distance between either(a) the edge of the door and frame rebate, or (b) the edges of two doors of a pair.

Door Function

Determine whether the door set is to be used as a Personnel Entry Door, an Emergency Escape (for staff and trained users) or a Panic Escape (for members of the public and untrained users). Where doors are perceived to have multiple functions, generally a hierarchy of importance will emerge; for example an opening that is an emergency escape might also be required to provide a one hour fire rating. In the context of door function, the escape function is critical.

Door Leaf

The blade of the security door that opens and closes within a fixed frame.

Door Location

Either internal or external to the building.

Door Viewer

Glass peep hole with magnification to allow viewing from the secure side of a door; so that safe egress can be determined before unlocking the door.

Double Leaf Door

A `pair` of leaves, comprising an active and passive leaf, usually in a three sided frame

Double Throw Bolt

A deadbolt that has two distinct extended positions, both are deadlocked.

Emergency Escape

A push bar, push pad or handle activation to comply with BSEN179; where only staff or trained users are likely to use the door set to leave the building in a fire or emergency situation.

Escape Night Latch

Allows internal lever handle operation for the door leaf by operating a sprung latch, and external unlocking by a key cylinder from the outside. Automatically locks on closing the door. The door set cannot be dead locked from the inside allowing for ease of escape in case of an emergency. Also known as `Emergency Night Latch`.

Escape Sashlock

Allow internal and external lever handle operation f the door leaf by operating a sprung leaf; whilst allowing locking of the door set by the integration of an external lock cylinder and internal cylinder or thumb turn to operate a deadbolt. Latch automatically engages on closing the door. However, when locked both the deadbolt and the latch bolt are withdrawn simultaneously by the inside lever handle, using a `split follower` function. Also known as ` Emergency Escape Sashlock`.

Electric Strike

A strike designed to be remotely controlled to permit the door to be opened without retracting the latch or bolt.


An orthographic projection of the vertical side of a hollow metal assembly (doors, frames, etc.).

Emergency Release

A safety device other than panic or fire exit hardware, which permits egress under emergency conditions.

Escutcheon Plate

Protective plate fitted around a lock cylinder hole of a security door.

Euro Profile Cylinder

A cylinder lock mechanism using a cam actuator.

External Override

External lockset which overrides fire exit hardware if external entry is required.

Finger Protection

Strips/guards to prevent pinching of fingers in the hinge gap on the inside and/or outside of a door set. Used where vulnerable, elderly or children have unsupervised access to the door set.

Fire Exit Door

Security doors designed with emergency exit hardware.

Fire Exit Hardware

Exit hardware, which has been investigated and labeled for both “Panic” and “Fire Protection” for use on swinging labeled fire doors.


A product which has successfully met all conditions of acceptance of the fire test standard specified in the governing model or building code, is “Listed” or “Classified” and eligible for labeling by a recognized testing agency having a factory inspection service.


The top of the concrete or structural slab. Also referred to as Finished Floor.

Floor Clearance

The distance between the bottom of the door and the top of the material directly below the door. This varies with applications, such as concrete, any floor covering, and/or a threshold. Note:
When the frame is installed on the floor without additional coverings: Floor Clearance is the distance between the bottom of the door and the top of the floor.

When additional floor coverings are used: Floor clearance is the distance between the bottom of the door and the top of the floor covering

When a threshold is used: Floor Clearance is the distance between the bottom of the door and the top of the threshold.

Floor Covering

Any material applied on top of the floor.

Flush Bolt

A rod or bolt, which is mounted flush with the edge or face of the inactive door in a pair, to lock the door to the frame at the head and/or cill.

Flush Door

A door having flush surfaces, with no glass lights, panels, louvers or grilles.

Frame Section

Cross cut of a frame member.


An archaic numeric value used to define a range of thickness of material.


Steel that is zinc-coated by the hot-dip process.


The process of installing glazing materials.

Glazing Material

A transparent or translucent material used in door assemblies and windows.

Hand (of door)

A term used to designate the direction of a door swing.


Any mechanism which is designed to perform an operable function in the use of a door and frame.

Hardware Schedule

Complete listing of all hardware specified for a project, organized by opening numbers including hardware sets, manufacturers names, template numbers, and special hardware locations. Prepared in accordance with the industry standards and adopted formats.

Hardware Supplier

The entity providing the products specified in the Approved Hardware Schedule.

Head or Header

The horizontal member which forms the top of a frame.


A hardware device generally consisting of two metal plates having loops formed along one edge of each to engage and rotate about a common pivot rod or “pin;” used to suspend and support a swing door in its frame.

Hinge Reinforcement

A metal plate attached to a door or frame to receive a hinge.

Hinge Side

The face of a door, which is opposite to that which contacts the frame stops.

Hollow Metal

A term used in reference to such items as doors, frames, partitions, enclosures and other items, which are fabricated from cold formed metal sheet, usually carbon steel.


The person or persons who installs the door.


Seals used for fire rated doors that expand when exposed to heat/fire.


The vertical frame member forming the perimeter of a frame.

Hinge Jamb

The jamb to which hinges are fitted.

Strike Jamb

The jamb at the leading edge of a door, in which a strike/keep may be installed.

Jamb Depth

The dimension of a frame member measured perpendicular to the structure.

Jamb Width

dimension from one face of the jamb to the other.

Keyed-Alike Cylinders

Cylinders which are designed to be operated by the same key. (Not to be confused with Master Keying cylinders.)


Cylinders requiring specific individually designed keys for operation.


A plate applied to the face of the lower rail of a door to protect against abrasion or impact loads.


An ornamental functional round handle on a door, generally used to actuate a latch or lock.


A hardware mechanism having a spring-activated beveled-end bolt, retractable by a knob or lever handle, but no locking device; used to hold a door in its closed position.

Leading Edge

That vertical edge of a door, which is opposite the hinge edge.


An individual door blade, used either singly or in multiples, (leaves).

Leaf & Half

Double security doors with the active leaf wider than the passive leaf.

Leaf Selector

Fixed at the centre of the header this allows double doors to latch in the correct sequence (i.e. passive leaf first, then the active leaf).

Lever Handle

A bar-like grip, which is rotated about a horizontal axis at one of its ends to operate a latch.

Limit Stay

A device, fitted to the door head, designed to hold the steel door leaf at a 90 degree angle.


A hardware mechanism having a retractable bolt operated by a key, thumb turn or other means, designed to hold a door securely closed against unauthorized opening.

Lock Faceplate

The exposed plate, which sets in the edge of a door to cover a lock mechanism.


A series of slats or blades, or piercings to allow passage of air. It may be either an inserted assembly or welded internally.


Electrically operated magnetic lock, usually operated remotely or by local permission switch or break glass unit.

Master Key

A key designed to operate a group of cylinders, each of which may be set to a different individual key.

Master Keying

A system of keying cylinders so that one master key will operate all of them, secondary keys will operate only certain groups of them, and other keys will operate only certain individual cylinders.

Mineral Core

Fire resistive insulating filler material used to form the cores of certain types of steel door.

Mortised Lock

A lock designed to be installed in a recessed preparation rather than applied to the door’s surface.


A member within a frame, separating either doors, a door and sidelights, glazed areas or side panels. A mullion between two doors of a pair may be either fixed or removable.


A bar or formed material separating panes of glass within a door, sash, or glazed frame.

Oval Cylinder

Oval shaped cylinder lock mechanism using a cam actuator.

Over Panel / Top Panel

A fixed or demountable metal faced panel installed above a door set to fill an oversize opening, as a cheaper and more functional alternative to a very large door. May be glazed or louvred.


Plastic shims used for installation between the door frame and structure

Passive Leaf

The leaf of a pair of doors which does not contain a lock. The secondary steel door in a pair of security doors (last to open, first to close).

Powder Coating

Polyester powder coated finish to a steel door.


Steel door leaves which are attached to the frame, in the works, ready for installation.

Primer / Prime Paint

Paint coating used as a base for finish paint.

Pull Handle

A handle or grip designed for attachment to a door to facilitate opening and closing.

Push Pad

A single point locking device with a pad or paddle handle to allow ease of activation of a single door set or the active leaf of a double door set.


A stainless steel rectangular trim mounted to push open a security door.

Ral or BS Number

An internationally recognised system of paint coding to promote colour conformity and systematic finishing.


On a frame, the area that is between the stop and the face, capable of accepting doors, panels or glazing materials.


The horizontal structural member forming the top or bottom edge of a door or sash, or located at an intermediate height in a door, separating panels or glazed areas.


The element of the frame member, which extends inward from the face, to the throat, perpendicular to the wall.


The projection and/or space between the frame face and the finished wall to produce an aesthetic or architectural design.

Roller Latch

A hardware device for holding a swing door in closed position. It consists of a spring-loaded roller mortised into the door edge so as to engage with a groove strike mortised into the frame jamb.


A lock incorporating a deadbolt and latch that can latch closed without a key.

Seamless Door

A door having no visible seams on its faces or edges.


A fixed light of glass located alongside a door or doors within the same frame.

Single Rebate Frame

A frame having only one rebate.

Square-Edge Door

A door having vertical edges that are perpendicular to the plane of its face.

Stainless Steel

An alloy of iron containing at least 11% chromium, which provides corrosion resistance.


The vertical structural member which forms the edge of a door.


An opening or retaining device provided in the head or jamb of a frame, or in the edge of the meeting stile of an inactive door to receive a lock or latch.

Surface Bolt

A rod or bolt mounted on the face of the inactive door of a pair to lock it to the frame head and/or cill; operated manually by means of a small knob.

Template (for Hardware)

A precise detailed layout or pattern for providing the necessary preparation of a door or frame to receive hardware.

Templated Hardware

Hardware manufactured in accordance with a specific template.

Thermal Bow

A temporary condition, which may occur in exterior doors due to the inside-outside temperature differential. The extent of this condition may vary with door color, door construction, length of exposure, etc. This condition can often be alleviated by painting the outside surface of the door a light color.

Three Point Locking

An emergency exit door bolting system which secures the door leaf into the frame by three different lock points (usually at the head, into the slam side jamb and into the threshold). Three point locking provides greater locking strength than single or two point locks, however consider also the strength of the frame, the leaf and the supporting structure (ie the wall).


A raised member at the floor extending between the jambs of a frame.

Thumb Turn

A permanently attached small lever which, when turned, operates the bolt on a lock in the same manner as a key.


Permissible deviation from a nominal or specified dimension or value.


A framed area immediately above a door opening and containing fixed glass, an operating sash, panel or other filler.

Two Point Locking

An emergency exit door bolting system which secures the door leaf into the frame by two different lock points (usually at the head and into the threshold).

Viewed from Inside

When surveying the door opening/structure/aperture from the inside of the building

Vision Panel

A glazed opening in a door.


Material applied to the edges of a door or to the inner edges of its frame to close the clearance opening and minimize or restrict the passage of air, moisture, sound, smoke, and/or dirt.



A weld which is unbroken, having no unwelded gaps or spaces, over its entire length.
Welding Arc / Fusion Welding

A process for the joining of metal parts, with the necessary heat being provided by an electric arc struck between an electrode and the metal or between two electrodes. The arc is shielded from the atmosphere (oxygen) by flux or inert gas. A filler metal may or may not be used depending upon the application.

Mig Welding

A process of fusion welding which incorporates a shielded automatically fed bare electrode in wire form enveloped by a stream of Metal Inert Gas.

Spot Welding

A form of resistance welding commonly used to join two overlapping pieces of metal.

Tig Welding

A process of fusion welding, which uses Tungsten Inert Gas to protect the weld zone from the atmosphere.

Zintec Steel

Zinc coated steel

Posted by Paul Marshall

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