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Awning Sash
A frame in which the panes of a window are set. The frame is built in such a way that the bottom swings outward in a window frame.

Awning Window Unit
A combination of a frame, one or more awning sashes, weather-strip and an operating device assembled as a complete and properly operating unit; screens and/or storm sash are optional; the unit may contain one or more fixed or non-operative sashes in combination with the operative sash.

Bay Window

Bifold Door
A segmented, hinged door that folds into itself and slides on a head track to the side when opened. A typical 4-0, 5-0, or 6-0 door is made up of four door segments: two folding to the right and two to the left. This door was first used during the 19th century. Bottom Rail
A horizontal rail at the bottom of a sash, door, blind or other panel assembly.

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A door hinge with one leaf mortised or routed into the door frame jamb and the other into the edge of the door. The leaf of the hinge can be radiused or square. A standard residential interior hinge measures 3 1/2 x 3 1/2 inches when laid out flat. A standard residential exterior hinge will measure 4 x 4 or 4 1/2 x 4 1/2 inches.

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Café Door
A single door or pair of half-width doors, hung in the middle of a doorway, that swing both inward and outward to allow entry; similar to saloon doors in the Old West.

Casement Sash Unit
A combination of frame, casement sash, weather-strip and operating device assembled as a complete and properly operating unit; screens and/or storm sash are optional.

Casement Window
A window in which the frame is built in such a way that the sash can open out like a door when installed in a window unit. Historically, casements were the first working windows. These windows were strategically placed throughout a house to capture breezes and direct them through the rooms. Screens were placed internally to prevent bugs and dirt from entering the house.

Molded or surfaced four-sided wood pieces of various widths and thicknesses, used for trimming door and window openings. A casing may be classified as exterior or interior as far as window and exterior door frames are concerned.

Check Rail
In double-hung windows, this is the bottom rail of the upper sash and the upper rail of the lower sash, where the lock is mounted. It is also know as a Meeting Rail.

Combination Door
A door that is made with a wood panel as the bottom half and a screen for ventilation as the top half. Also called a ventilating door.

Composition Door Panel
A door panel of a material other than solid wood or plywood.

Moisture or humidity in the air that forms on a cool surface such as a pane of glass. When moist air comes in contact with a cool surface it shrinks. If it shrinks enough to reach 100% humidity or the dew point, moisture will form on the cool surface. This is demonstrated when the out side of a glass of ice tea sweats. CoreThe center of plywood or crossbanded construction; it may consist of lumber (solid or glued), particle board or veneer. Also core unit; innermost layer in veneered door construction.

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A groove or rectangular section for receiving the end of a board.

Decorative Entry System
An entryway made up of a door in a frame, one or two sidelights, and a transom.

A separation of piles or layers of wood through failure of the adhesive.

The weight of a substance per unit volume; for example, 23 lbs. per cubic foot.

Dimensional Stability
The ability of a material to stay put or to resist changes in its dimensions due to temperature, moisture or physical stress variations; stability of a material.

A millwork assembly of stiles, rails, and panels that swings, slides, tilts up or folds in order to close an opening in a wall or cabinet. A modern door may be used on the exterior or interior, and may be either flush or panel type. Historically, there were two types of doors: ledge and brace (or batten) and paneled doors. An exterior door used before the 17th century, the ledge and brace style was constructed from vertical panels that were held together with a Z-shaped brace nailed to the back. A Tudor-style door is similar to the ledge and brace except that it is held together by oak planks across the back instead of a Z-brace. In the 1600's, the paneled door came into use as an interior door. The first examples were made with two or four panels, but then near the end of the 18th Century, a six-paneled version was made, called a Georgian door.

Door Casing
Same as casing; may be an interior or exterior door casing; exterior door casings are installed only on the outside of exterior door frames, especially on wood facing wood-frame exterior walls.

Door Frame
A group of wood parts machined and assembled to form an enclosure and support for a door; door frames are classified either as exterior or interior door frames.

Door Jamb
The part of a door frame that surrounds and contacts the edges of the stiles and the top rail of a door. Jambs may be classified as head or side jambs and as plain or rabbeted.

Door Panel

Door Trim
The moldings required to finish or trim the side of a door frame, consisting of two pieces of side and one of head casing.

Two panes of glass separated by an air space; double glazing may be accomplished by storm sash or insulating glass; this term sometimes refers to storm sash.

Double Glazing Panel
A removable glass panel that allows insulation and condensation control.

Double-Hung Window
Two sashes, top and bottom, that slide vertically past each other, joined by a meeting rail and held in any open position by means of weights or one of several types of balancing devices.

Dovetail Joint
A joint formed by inserting a projecting wedge-shaped member into a correspondingly shaped cutout member.

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An exterior door frame with or without transom or sidelight (usually used for the main or front entrance of a structure) with decorative exterior trim; trim may include pilasters, entrance head or cap or a decorative exterior casing.

Entrance Door
A door on the front or main entrance of a structure; may be single or paired.

Exterior Casing
A casing that trims the exterior of a window or door frame and serves as the boundary molding for the siding material; forms a rabbet with the blind stop or a jamb for the screen.

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The person or firm that assembles all the component parts into a complete window, door or sash unit.

The placement (or arrangement) and sizing of the windows and exterior doors of a building. In Greek architecture, windows began as simple openings in temples. These openings began to contain glass in the 13th century, when clear glass was available for buildings such as Westminster Abbey. Another important shift in fenestration occurred in the 20th century when large windows became important components in commercial buildings.

A series of fingers machined on the ends of two pieces to be joined, which mesh together and are held firmly in position by a water-resistant adhesive.

The interior or exterior finish of a structure; the finished or actual size of a piece of lumber; the protective coating given a wood member; upper or select grades of softwood lumber.

Refers to windows that are non-venting or inoperable.

Flat Door Panel

Flush Door

French Door
An interior or exterior door consisting of stiles, top and bottom rail and divided glass panels or lights; often used in pairs as a casement or terrace door. In the 19th century, glass was being added to door construction, mainly in French and German homes, on internal doors leading to rooms containing more natural light, such as conservatories, glass houses and vestibules.

French Casement Window
Two casement sashes, each hinged on one stile and opening in the middle but with no center mullion. This allows a smaller rough opening to make egress since there is a large unobstructed opening.

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Garden Window
A box-shaped window that hangs outside the house and can be used as a greenhouse for plants. It has a slanted glass roof that pulls in heat and light from the sun.

The insertion of glass into sashes and doors. Glazing also refers to the lowest quality of plate glass. The purpose of glazing is to retain the glass adequately under the design load, provide effective weathering sealing, prevent loads or pressure points on the glass resulting from building movement, prevent glass-to-metal contact, and minimize glass breakage from mechanical or thermal stress.

An arrangement and direction of alignment for wood elements or fibers; can be straight or spiral grain; also used loosely to indicate texture.

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A term describing the swinging direction of a door as one stands on the side of the door from which security is desired, namely the outside.

One of the botanical groups of trees that has broad leaves in contrast to the needle-like leaves of the conifers or softwoods; hardwoods are deciduous (they shed their leaves in the fall or at the end of each growing season).

A jointed or flexible device on which a door or window turns. The earliest known hinges were T-shaped devices called strap or cross-garnet hinges. They were made of wrought iron with a cross bar fixed vertically to the door frame, and attached with nails to the door. In the 18th century, hinges for interior doors were H-shaped or L-shaped, and attached to the door with nails.

Hollow-Core Flush Door
A flush door with a core assembly of strips or other units of wood, wood derivative or insulation board, that supports the outer faces and has intervening hollow cells or spaces.

Horizontal Light
A light or cut-out formed by a horizontal bar extending from stile to stile of a sash or door.

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Insulating Glass
Two or more pieces, lights or panes of glass separated by a hermetically sealed air space, typically 3/16 to 1 inch wide. Manufacturing of insulating glass began in 1930.

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The top and two sides of a door or window frame that contact the door or sash.

The joining of two pieces of wood by nails, glue, adhesives or other means; joints may be joined end to end, edge to edge, end to edge, or end to face.

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A thin, polished metal plate applied to the bottom rail or bottom of a door to prevent denting and soiling of the wood surface caused by the kicking action of persons opening the door; kickplates may be applied to one or both sides of a door.

Kick Rail
A rail located approximately 10 to 12 inches from the bottom of a hollow-core flush door frame, used primarily on institutional doors.

Anything that is wood seasoned in a kiln by means of artificial heat, humidity and circulation; kiln-dried wood may refer to wood with various moisture content percentages.

A branch or limb embedded in a tree and cut through during lumber manufacturing; the size of a knot is determined by averaging its maximum length and width of the knot.

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Lock Block
A solid or glued block of wood the thickness of a hollow-core interior door or steel exterior door stile, which is joined to the inside edge of the stile and to which a lock is fitted.

Lock Rail
The intermediate rail of a door at lock height.

An opening with a series of horizontal slats, called louver boards, arranged sloping downward to permit ventilation but exclude rain, sunlight or vision. Louvers can be made in various shapes.

Louver Door
A panel door with part or all of the panels replaced by louvers; a blind door.

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Refers to something worked into a form or shape.

A relatively narrow strip of wood, usually shaped to a curved profile throughout its length; used to accent and emphasize the ornamentation of a structure and to conceal surface or angle joints.


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The main post at the start of stairs and the stiffening post at the landing.

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Panel Door
A door constructed with panels, stiles, and rails on a wood surface. Combining several smaller components (stiles, rails, loose-fitting panels) into one door allows panel doors to maintain their shape while expanding and contracting with weather and temperature changes. This door style was first developed in the eighteenth century as an alternative to batten doors, which didn't function well under moisture and climate changes.

Passage Door
An interior door connecting two inside rooms or used for a closet door; this door type does not have the same strength, insulation or security requirements of an exterior door. Panel construction on passage doors is designed to allow the wood to expand and contract with changes in moisture and temperature; the center panels are allowed to float within the door's frame.

Patio Door
A door that opens onto a patio, deck or backyard of a house, usually made of glass to allow for viewing. Originally homeowners asked for glass doors from a glazer, or someone who handles glass. This specialty product was created by distributors in small shops. In the 1960s when aluminum sliding doors became very popular, window manufacturers realized they could make patio doors to fill the openings that used to be filled by solid doors. At that point, the window companies started heavily promoting patio doors, made in aluminum, vinyl and wood. Door companies now also make them in wood, composites and steel. The same as a stationary or fixed sash, a picture sash or window usually implies a relatively large-sized sash.

Prehung Door Unit
A precut and assembled unit consisting of a door with the locking or passage hardware hung on hinges in a wood frame.

Prime Coat
The first coat of paint in an application that consists of two or more coats.

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The cross or horizontal members on the framework of a sash, door, blind or other panel assembly.

Raised Door Panel
A door panel on which the edges have been contoured or shaped to provide an aesthetically appealing, three-dimensional effect.

Rough Opening
The opening in a wall where a window is to be installed.

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A single assembly of stiles and rails in a frame for holding glass, with or without dividing bars or muntins, to fill a given opening; it may be either open or glazed.

Sash Cord
The rope or chain attaching the sash to the counter balance in a double-hung window.

Sash Door
A door that is constructed with the bottom half made up of a wood panel and the top half made of glass to allow for a view.

Sash Lift
A handle built into the bottom rail of the lower sash on a double-hung window.

Sash Weight
The concealed cast-iron weight used to counterbalance the sash in double-hung windows.

Screen Door
A door that is made with a wood panel as the bottom half and a screen for ventilation as the top half. Also called a ventilating door or combination door.

A wood assembly of stiles and rails to form a frame that encloses panels used in conjunction with door and window frames; may also consist of vertical boards cleated together. Shutters have been around since windows were first used. By the 16th century, interior paired shutters were used throughout Europe, often stacked in two or four tiers. By the late 18th century, interior shutters were made with louvered and solid panels.

An assembly of stiles and rails, with or without a wood panel, containing a single row of glass panels or lights and installed on one or both sides of an exterior door frame, especially a front entrance door frame. Also used in older houses to frame interior doors.


Single Glazing
The use of single panes of glass in a window.

Single-Hung Window
Similar to a double-hung window with the top sash stationary or inoperative while the bottom sash operates freely; also, a vertical slider.

A window installed in a roof and assuming the same slope. Depending on which direction they face, skylights can bring in more light and heat than windows. For example, in the summer months, an unshaded south-facing skylight will bring in more direct sunlight and heat than a window. In a cold climate, a north-facing skylight gives almost five times more light than a north-facing window with almost the same amount of heat loss.


Solid-Core Flush Door
A flush door consisting of a core of solid wood blocks or strips with cross-banding and face veneers, or with face veneers only.

Solid Door Panel
Beveled on one or two sides.

Stationary Sash
A fixed or inoperative sash, often used in combination with other types of window and sash units; intended primarily for viewing purposes and for admitting light.

The uprights or vertical outside pieces of a sash, door, blind or screen.

Stop Bead
A molding used to hold, position or separate window parts.

Swinging Patio Door
A patio door of two or three sections, one of which swings inward or outward like a regular door, with the other sections fixed.

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Tilt Window

Tongue and Groove Joint
A joint formed by the insertion of the tongue of one wood member into the groove of the other; modifications include tongue and groove rabbet joint, dado tongue and rabbet, tongued shoulder joint, dado and rabbet joint, dado and rabbet joint, dado and lip joint.

Top Rail
The top rail of a sash, door, blind or other similar panel assembly.

A small opening above a door or window separated by a horizontal member that usually contains a sash or a louver panel hinged to the transom bar. Transoms, or fan lights, were first used in the 18th century on exterior doors. They increased the amount of light let into the front hall, and because of them, the size of the front door could be reduced. They probably encouraged the Victorian use of stained glass for front doors.

Millwork, primarily moldings and/or trim, that finishes off window and door openings, fireplaces, walls and other members.

Triple Glazing
Three panes of glass with an air space between each pane.

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A thin sheet or layer of wood, usually rotary-cut, sliced or sawn from a log, bolt or flitch.

Veneered Construction
A stile or rail consisting of a core, two edge strips and two face veneers bonded together under pressure with adhesives.

Ventilating Door

Material or device for sealing openings, gaps or cracks of venting, window and door units.

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Any distortion in the plane of a door itself and not in its relationship to the frame or jamb into which it is hung.

Variously shaped metal, vinyl, plastic or molded fiber strips that fit tightly against the sash or door frame parts to prevent air infiltration through cracks. Cold air entering the house in winter can account for up to 35% of the heating load. Weatherstripping can reduce the load to 20%.

Window Casing
May be interior or exterior; an exterior window casing is most commonly installed on window frames for wood facing wood frame exterior walls; along with the blind stop, it forms the rabbet for the storm sash or screen.

Window Frame
A group of wood parts machined and assembled to form an enclosure and support for a window or sash.

Window Jamb
The part of the window frame that surrounds and contacts the window or sash that the frame is intended to support.

A wall opening in a building added for the purpose of letting in light and air, usually sealed from the elements in some way, using a frame and sash containing glass or another type of transparent material, and usually able to be opened and shut. Windows containing glass began being heavily used in the late nineteenth century with advances in glass technology and frame construction. Windows gave building occupants options about views, ventilation, and exterior design.