Exit Device:
A door-locking device designed to grant instant exit by pressing on a cross bar that releases
the locking bolt a latch.

Fiberboard:
A broad term used to describe wood sheet material of widely varying densities manufactured of a refined or partly refined wood fibers; usually manufactured by the "wet process" whereby the wood fibers are put into suspension and pressed into a board.

Finger Jointing:
A method of joining wood pieces milled in the shape of fingers, which mesh together and are held firmly in position by water-resistant adhesive. This method has enabled the millwork industry to create longer lengths of wood and to utilize shorter pieces of raw material. Finger jointing is not a new woodworking technique but has been vastly refined. So precise can the joint now be made on such items as mouldings, door and window jambs, and doors that the lines of joining are barely perceptible. When there is no great variation in grain or color, the end-welded pieces appear as one.

Fire Door:
A solid-core flush door incorporating noncombustible materials or fire retardant chemicals to warrant specific fire ratings.

Flashing:
A metal or plastic strip to prevent water and air leakage between the window or door frame and the surrounding wall; attached to the outside face of the head and side jambs.

Flat Astragal:
A non-rabbeted astragal applied to swing doors; the astragal is applied to the face of the meeting stile of one of the doors.

Flush Bolt:
A door bolt so designed that when applied it's flush with the face or edge of the door.

Flush Door:
A door consisting of a core, crossbanding and flat face veneers or a core and flat face veneers only.

Flute:
A long, rounded groove machined along the grain of a wood member, e.g., a pilaster; may be "thru fluted" or "stop fluted"; shallow or deep concave or groove cut back of surface; repeated flutes produce texture.

Folding Door:
One of two or more sliding doors hinged to move laterally in an opening; "accordion type" door; may be used for a folding partition; a complete unit may be obtained consisting of doors with butts applied, track and guide hardware, door pulls and door frame (optional).

Frame:
Parts which enclose the window or door sash; they are attached to the wood members lining the rough opening. (Usage - Vertical frame members are called "side jambs"; the top, horizontal piece is the "head jamb"; the bottom, horizontal piece is the "sill".)

French Door:
An interior or exterior door consisting of stiles, top and bottom rail and divided glass panels or lights; often used in pairs; "casement" or "terrace" door.

Galvanized Nails:
Steel nails which are coated with zinc as a protection against rust and staining; hot-dipped galvanized; non-ferrous.

Glazing:
Glass or other transparent materials, used for windows; also the act of installing the glass.

Hardwoods:
One of the botanical groups of trees that has broad leaves in contrast to the needlelike leaves of the conifers or softwoods; hardwoods are (1) deciduous (shed their leaves in the fall or at end of each growing season), (2) have shorter length wood fibers than softwoods, (3) contain cells (vessels) of relatively large diameters (in addition to the wood fibers) and (4) have seeds enclosed by an ovary.

Hinged Door:
An exterior or interior door hung by attaching butts to the stile so that the door swings on a vertical axis; may be single (swinging thru 90 degrees) or double-acting (swinging thru 180 degrees); double-acting doors do not require a door stop; conventionally hinged.

Home Centers:
Millwork retailers, more properly termed "lumber and building materials dealers", are primarily responsible for the final distribution phase of millwork. Purchases millwork from the millwork jobber, manufacturer, or manufacturer' rep for subsequent sale to the ultimate user.

Inactive Door:
That leaf of a pair of doors that does not contain a lock,  (or Leaf) but is bolted when closed, and to which the strike is fastened to receive the latch or bolt of the active door.   

Insulated Glass:
Two or more (generally two) pieces of lights or panes of glass separated by a hermetically sealed air space.