Glossary of Terms
Welcome to our Window and Door Glossary – a comprehensive resource designed to familiarize you with the terminology associated with windows and doors. Whether you're a seasoned homeowner or navigating the realm of home improvement for the first time, understanding these terms is pivotal in making informed decisions.
Whether you're contemplating the energy-efficient benefits of low-E glass or discerning the distinctions between a casement and a double-hung window, our glossary serves as your reliable guide.
Awning: A single (or double) operational window where the bottom of the sash swings outward for ventilation.
Astragal: The exterior center post or molding on a double door, attached to the secondary or inactive door panel.
Bay: Three connected windows, typically composed of a larger fixed window in the center and two smaller operational windows on either side, arranged in a 30-degree or 45-degree angle formation.
Bow: Four or more connected windows, fixed or operational, arranged in a 10-degree or 15-degree angle formation.
Brickmould: An exterior molding around the window, serving to seal and cover the exposed window opening, insulation, interior jambs, etc.
Casing: The interior decorative molding/trim covering the inside edge of the jambs and the rough openings between the window and the wall.
Double glazing: The use of two panes of glass in a window frame to enhance energy efficiency and provide other performance benefits.
Double hung: A window with two vertical operating sashes that slide up and down for ventilation.
Drip cap: An exterior aluminum molding placed on the top of the brickmould or capping of a window frame.
Egress window: A window large enough for emergency exit.
Fixed: Non-opening or non-operational window.
Flashing: Aluminum attached to the outside of the head or side jambs of a window to provide a weather barrier, preventing leakage between the frame and the wall.
Gasket: A weatherstrip used to create a watertight seal between the sash and the window frame.
Glazing: The glass panes in the sash of a window.
Glazing stop: The molding or part of the window sash that holds the glass in place.
Grill: A bar used to visually separate glass into multiple lites, also known as internal grid, muntin bar, or window pane divider.
Header: A heavy beam extended across the top of the rough opening to help support the weight of the building.
Lite: Glazing framed by muntin bars and/or sash in a window or door.
Low-E glass: A term referring to a low emissivity coating placed on the glass surface to restrict the passage of radiant heat.
Moulding: A trim installed around the exterior perimeter of a window frame.
Mullion: The connectors installed between individual windows in a multiple-unit window.
Muntin: A bar used to visually separate glass into multiple lites, also known as internal grid, grill, or window pane divider.
Operator: A metal arm and gear that allows for easy opening or closing of projecting windows.
Pitch: The degree of the slope in a roof.
Rails: The horizontal parts of a window sash or door panel.
Rough opening: The opening in a wall to accommodate the installation of a window or door.
Sash balance: A system of weights or coiled springs that assist in the raising and lowering of single-hung and double-hung windows.
Seat: A wooden board installed on the bottom contour of a bow or bay window to provide a seat or shelf space.
Shims: Wooden wedges used to secure and level windows in the rough opening.
Sidelites: Tall and narrow fixed glass on either (or both) sides of an entry door.
Sill: The horizontal part forming the bottom of a window or door frame.
Sill course: The row of bricks across the bottom of a rough opening.
Simulated divided lite: A method of constructing windows in which grills are attached to the inside and outside of glass panels to simulate the look of true divided lites.
Single Hung: A window in which the top sash is fixed (or inoperable), and the bottom sash slides vertically up and down for ventilation.
Solar gain: The amount of heat that has passed through the glass of windows and doors and has collected inside the home.
Stud: Wood installed vertically and horizontally to build a frame or wall.
Transom: A smaller window attached above a door or another window.
Triple glazing: A window glazed with three panes of glass enclosing two separate air spaces.
U-Factor: A measure of heat transmission through a wall or window, with lower values indicating better insulating value.
Vapor barrier: A watertight material used to prevent the passage of moisture through floors, walls, and ceilings.
Venting unit: A window or door that opens or operates.
Wind Load: Force exerted on a surface by moving air.
Still have questions? The dedicated team at Portland Window and Door is here to assist you in making informed choices for your home's windows and doors. Contact us today for personalized support and expert advice tailored to your unique needs.