Glossary
Terms are listed alphabetically. Where a term has a specific meaning in the context of this guide that differs from general usage, that distinction is noted.
Astragal A vertical molding or strip attached to one panel of a double door — typically the inactive panel — that the active door closes against. Provides a stop surface and improves the seal between panels on French doors and other paired configurations.
Backset The horizontal distance from the edge of the door to the center of the lockset bore. Standard residential backsets are 2⅜ inches and 2¾ inches. The backset determines which strike plate and latch are compatible with a given door and frame — verify before purchasing replacement hardware.
Ball-bearing hinge A hinge with ball bearings between the hinge leaves and the barrel, reducing friction and wear under load. Recommended for exterior doors and heavy solid-core interior doors. See Hardware — Hinges.
Barn door A door that slides along a surface-mounted overhead track rather than swinging on hinges. Named for its agricultural origin. See Styles & Configurations — Barn doors.
Bifold door A door configuration consisting of two panels hinged together that fold against themselves when opened, guided by a top track. Commonly used for closets. See Styles & Configurations — Bifold doors.
Bore The hole or holes drilled through a door to accept lockset hardware. The face bore accepts the knob or lever cylinder; the edge bore accepts the latch assembly. Standard face bore diameter is 2⅛ inches for most residential locksets.
Brick mold The exterior casing profile used on the outside of an exterior door frame, traditionally used where a door frame meets brick or masonry. In residential wood-frame construction, brick mold is the standard exterior trim profile regardless of the wall material.
Butt hinge The standard residential door hinge: two rectangular leaves joined by a pin, mortised flush into the door edge and jamb. The most common hinge type in residential construction. See Hardware — Hinges.
Casing The trim applied to both faces of a wall around a door opening, covering the gap between the door frame and the wall surface. Casing is both functional — concealing the rough framing and shims — and decorative.
Clear opening width The usable width of a door opening when the door is open, measured from the face of the door stop to the face of the open door. Always less than the nominal door width. The relevant measurement for accessibility and egress compliance. See Accessibility & Code — Minimum door widths.
Compression set The permanent deformation of a foam or rubber weatherstripping material after prolonged compression. A weatherstripping material that has taken a compression set no longer springs back to fill the gap and must be replaced. See Weatherstripping & Sealing — Why weatherstripping fails.
Cripple stud A short stud above a door header or below a window sill that fills the space between the framing members. Cripple studs transfer load from the top plate to the header but do not carry the primary structural load of the opening.
Dead latch A secondary latch plunger adjacent to the main latch bolt on most residential locksets. When the door is closed against the door stop, the dead latch plunger is depressed, locking the main latch in the extended position and preventing it from being retracted by shimming or carding. A functioning dead latch is an important security feature — verify it is engaging correctly when a lockset is installed.
Deadbolt A lock with a solid steel bolt that extends into the door jamb and strike plate independently of the latch mechanism. Required on all exterior entry doors for adequate security. See Hardware — Deadbolts.
Door shoe A profile mounted to the bottom of a door that integrates a sweep seal against the threshold. Provides a cleaner and more durable bottom seal than a surface-mounted door sweep. Requires door removal for installation. See Weatherstripping & Sealing — Thresholds and door shoes.
Door stop (frame) The narrow strip of wood projecting from the interior face of the jamb that the door closes against. Not to be confused with a door stop (hardware). The door stop establishes the closed position of the door and is part of the seal surface for compression-type weatherstripping.
Door stop (hardware) A device that prevents a door from swinging too far and damaging the wall, handle, or hinge. Available in wall-mounted, floor-mounted, and hinge-pin configurations. See Hardware — Door stops.
Door sweep A seal mounted to the bottom of a door that closes against the threshold to block air, water, and pests. Available in surface-mounted and automatic configurations. See Weatherstripping & Sealing — Door sweeps.
Dummy lockset A non-functional lockset with no moving latch or lock mechanism. Used on the inactive panel of French doors or on closet doors held closed by a magnetic catch. Provides the appearance of hardware without the function.
Egress The ability to exit a space in an emergency. Building codes establish minimum egress requirements for sleeping rooms, including minimum door dimensions and the requirement that egress doors be operable from the inside without a key. See Accessibility & Code — Egress requirements.
Face bore The cylindrical hole drilled through the face of a door to accept the knob or lever cylinder of a lockset. Standard diameter is 2⅛ inches for most residential hardware. See also: Bore, Edge bore.
Finger-jointed A wood component — typically a jamb or casing — made from short pieces of wood joined end-to-end with interlocking finger joints and glued. Finger-jointed lumber is stable and paint-grade only; the joints read through stain. Common in pre-hung door frames.
Fire rating A designation indicating that a door assembly has been tested to resist fire penetration for a specified period — typically 20, 45, 60, or 90 minutes. The rating applies to the full assembly: door, frame, and hardware. See Accessibility & Code — Fire-rated doors.
Flush door A door with completely flat faces on both sides, with no panel detail. See Styles & Configurations — Flush doors.
French door A glazed panel door, typically used in pairs, with full or partial glass panels set into the stile-and-rail frame. See Styles & Configurations — French doors.
Hand (handing) The designation of which side a door is hinged on and which direction it swings, from the perspective of the person pulling the door open. A right-hand door has hinges on the right and swings away from you; a right-hand reverse swings toward you. Handing must be specified correctly when ordering pre-hung doors and some locksets.
Header The horizontal structural member spanning the top of a door opening, transferring the load from above to the jack studs on either side. Header size is determined by the span and the load above. Widening a door opening requires verifying that the existing header is adequate for the new span.
Hollow-core A door construction type consisting of a thin skin over a lightweight frame surrounding a cardboard honeycomb core. The most common interior door type in residential construction. See Door Materials — Hollow-core.
Jack stud The stud on either side of a door opening that supports the header directly. Also called a trimmer stud. The jack stud runs from the bottom plate to the underside of the header and carries the header load down to the foundation.
Jamb The vertical sides (side jambs) and horizontal top (head jamb) of a door frame. The jamb is the primary structural element of the frame and the surface into which hinges and strike plates are mortised.
Kerf A narrow slot cut into a material, typically by a saw blade. In door work, a kerf-in door sweep has a rubber fin that is pressed into a slot cut into the bottom of the door rather than being surface-mounted. Also used to describe relief cuts made in trim or casing to allow it to bend around curves.
King stud The full-height stud on either side of a door opening, running from bottom plate to top plate, to which the jack stud is nailed. The king stud and jack stud together form the trimmer assembly on each side of the opening.
Latch bolt The spring-loaded angled bolt that extends from the door edge and retracts when the handle is operated, allowing the door to open. Distinct from a deadbolt, which is operated independently. See also: Dead latch.
Lockset The combined assembly of handle and latch mechanism. Residential locksets are categorized by function: passage, privacy, keyed, and dummy. See Hardware — Locksets.
Miter An angled cut — typically 45 degrees — used to join two pieces of casing or molding at a corner. Mitered casing joints are the standard method for joining door casing at the head.
Mortise A rectangular recess cut into the door edge or jamb to accept a hinge leaf or strike plate flush with the surface. Proper mortise depth is critical — too shallow and the hardware proud; too deep and the door binds. See Fit & Adjustment — Hinge adjustment.
Nominal size The stated dimensions of a door — for example, 2/8 (two-eight, meaning 2 feet 8 inches wide) by 6/8 (six-eight, meaning 6 feet 8 inches tall). Nominal size does not account for the reveal or frame — the actual clear opening will be smaller.
Over-mortised A condition in which a hinge mortise has been cut too deep, causing the hinge leaf to sit below the surface and pulling the door toward the hinge jamb. Results in hinge-side binding. Fixed by shimming the hinge leaf out with cardboard. See Fit & Adjustment — Hinge-side binding.
Patio door A large glazed sliding door providing access to an exterior deck, patio, or yard. Typically consists of one fixed and one sliding panel. See Styles & Configurations — Sliding doors.
Plumb Perfectly vertical, as verified with a level. A plumb hinge jamb is the primary alignment reference for door installation — everything else is adjusted relative to it. See Installation — Shim and plumb the hinge side.
Pocket door A door that slides into a cavity built into the wall rather than along the face of it. See Styles & Configurations — Pocket doors.
Pre-hung door A door unit consisting of the slab already hung on hinges within a finished frame, with hinge and strike mortises already cut. The standard choice for new openings or damaged frames. See Installation — Pre-hung vs. slab.
Rail The horizontal members of a stile-and-rail door — top rail, bottom rail, and any intermediate lock rail. Rails connect the vertical stiles and define the panel layout.
Reveal The gap between the door edge and the jamb on the hinge side, latch side, and head when the door is closed. A consistent reveal of approximately ⅛ inch on all three sides indicates a well-fitted door. See Fit & Adjustment — Understanding the reveal.
Rough opening The framed opening in the wall into which a door unit is installed. The rough opening is typically 2 inches wider and 2 inches taller than the nominal door size to allow for the frame and shims.
Shim A thin tapered wedge — typically cedar — used to fill the gap between a door frame and the rough framing and to adjust the frame to plumb and level. Shims are driven in pairs from opposite sides to create a parallel fill of any thickness. See Installation — Shim and plumb the hinge side.
Slab door A door panel without a frame. Installed into an existing frame, reusing the existing jamb, hinges, and hardware mortises where possible. See Installation — Pre-hung vs. slab.
Solid-core A door construction type using a composite wood block or particleboard fill within the stile-and-rail frame, covered by a wood veneer or hardboard skin. Heavier and better performing than hollow-core. See Door Materials — Solid-core.
Spar urethane A clear topcoat formulated for exterior use, with UV inhibitors and flexibility additives that allow it to move with wood through seasonal humidity changes. The appropriate topcoat for exterior wood doors. Standard interior polyurethane is not a substitute. See Finishing — Topcoat.
Spring hinge A hinge with an integrated spring mechanism that returns the door to the closed position automatically. Used to satisfy self-closing requirements at garage entry doors without a surface-mounted door closer. Adjustable for closing tension. See Accessibility & Code — Self-closing hardware.
Strike plate The metal plate mortised into the jamb that receives the latch bolt and deadbolt when the door is closed. Proper strike plate alignment is essential for reliable latching. See Fit & Adjustment — Latch and strike adjustment.
Stile The vertical members of a stile-and-rail door — hinge stile and lock stile. Stiles run the full height of the door and contain the hinge mortises and lockset bore.
Threshold The strip across the bottom of a door opening that the door closes against. Exterior thresholds typically include an integrated rubber or vinyl seal. See Weatherstripping & Sealing — Thresholds and door shoes.
V-strip A folded strip of metal or plastic weatherstripping that springs open to fill the gap between door and jamb. The preferred weatherstripping type for the hinge and latch sides of most hinged exterior doors. See Weatherstripping & Sealing — V-strip.
Weatherstripping The collective term for sealing materials applied around the perimeter of a door to block air, water, and noise infiltration. See Weatherstripping & Sealing.