honeycomb spaces within the sash and frame which help to insulate and
strengthen the window
amount of air that passes between a window sash and frame. In windows it
is measured in terms of cubic feet or air per minute, per square foot of
area. The lower the number, the less air the window lets pass through.
mechanism on the interior face of the sash that retains the window in a
partially open position for ventilation.
sloped extension from the frame that adds an aesthetically-pleasing
dimension to the exterior of the window.
Argon is a safe, odorless, colorless, non-toxic, non-flammable inert gas
that is commonly used in place of air between the glass panes of an
insulated Low-E glass unit to reduce temperature transfer.
A window unit in which the bottom of the sash swings outward for
for holding vertically sliding sash in any desired position through the
use of a spring or weight to counterbalance the weight of the sash.
A composite of three windows, usually made up of a large center fixed
unit and two flanking units at 30-,45- or 90- degree angles to the wall.
angled extension from the frame that adds an aesthetically-pleasing
dimension to the exterior of the window.
A composite of four or more window units in a radial or bow formation.
A type of external casing which frames windows and doors.
A rubber material that seals the glass to the spacer, creating an
airtight and watertight IG unit. Butyl has the lowest gas permeability
of all rubbers.
Lock and Keeper
The mechanisms which pull the sash together when placed in the locked
Small hollow tubes which penetrate the spacer system of an insulating
glass unit. They allow pressure equalization between manufacturing
locations, shipping, and installation locations. Since the insulating
glass unit is not permanently sealed, the air space cannot be filled
with Argon gas.
A window unit in which the single sash cranks outward, to the right or
Molding of various widths, thickness and shapes applied to the framework
of window and door units.
The U- and R-values measured from the center of the glass to 2-1/2"
from the frame.
On a double-hung window, the bottom rail of the upper sash and the upper
rail of the lower sash, where the lock is mounted.
A generic term referring to any of a variety of window units with one or
more curved frame members, often used over another window or door
Any material locked to the outside faces of doors and windows to provide
a durable, low-maintenance exterior surface.
A measure of the effectiveness of a window or glazing system to reduce
the potential for condensation. The higher the condensation resistance
factor, the more efficient the window and glazing system.
Energy transfer from one material to another by direct contact.
Heat transfer by currents that flow from a warm surface to a colder one.
A double-hung window in which the upper sash is shorter than the lower
A window unit that has two operable sashes which move vertically in the
A molding placed on the top of the head brickmold or casing of a window
or dual glazing
Use of two panes of glass in a window to increase energy efficiency and
provide other performance benefits.
A form produced by forcing material through a die. Most window frames
are clad with extruded vinyl or aluminum.
An architectural term referring to the arrangement of windows in a wall.
From the Latin word, "fenestra," meaning window.
Non-venting or non-operable window. Also known as picture window.
A thin strip of metal or synthetic material that diverts water away from
a window or skylight.
A replacement window with flush fin is used when replacing an existing
aluminum sliding window. This is the most commonly used replacement
Foam material placed in the airspace of the insulating glass in a window
to enhance the appearance and improve the performance of the window.
The enclosure in which window sash or door panels are mounted.
Glass in a window or door; the act or process of fitting with glass.
A plastic or wood strip applied to the window sash around the perimeter
of the glass.
The part of the sash or door panel which holds the glass in place.
A term referring to windowpane dividers or muntins, usually a type of
assembly which may be detached for cleaning.
The main horizontal member forming the top of the window or door frame.
A horizontal framing member placed over the rough opening of a window to
prevent the weight of wall or roof from resting on the window frame.
A window unit in which the top of the sash swings inward.
A combination of two or more panes of glass with a hermetically sealed
air space between the panes of glass. This space may or may not be
filled with an inert gas, such as argon.
Louver blades open to maximize airflow through opening.
The main vertical members forming the sides of a window or door frame.
In a modern double-hung window, the track installed inside the jambs on
which the window sashes slide.
Unassembled window or door unit.
A handle or grip installed on the bottom rail of the lower sash of a
double-hung window to make it easier to raise or lower the sash.
Glazing framed by muntins and/or sash in a window or door.
A common term used to refer to glass which has low emissivity due to a
film or metallic coating on the glass or suspended between the two
lights of glass to restrict the passage of radiant heat.
A slot or rectangular cavity cut into a piece of wood to receive another
A strong wood joint made by fitting together a mortise in one board and
a matching projecting member (tenon) in the other.
A wood or metal part used to structurally join two window or door units.
Applies to any short or light bar, either vertical or horizontal, used
to separate glass in a sash into multiple lights. Also called a
windowpane divider or a grille.
Any small bar that divides a windows glass. Also called a grille or
with nail-on frames are for new construction.
A large, arch-top window flanked by smaller windows on each side.
In a double-hung window, a strip of wood applied to the jamb to separate
Any glazed area in the walls or roof of a building pointed to the south
to take maximum advantage of the sun's heat without a mechanical (or
active) method of storage or distribution of the heat.
Non-venting or non-operable window. Also know as a fixed window.
The top and bottom horizontal members of the framework of a window sash.
The framed opening in a wall into which a window or door unit is to be
Resistance to thermal transfer or heat flow. Higher R-value numbers
indicate greater insulating value.
A framed sheet of glass within a window.
A single assembly of stiles and rails made into a frame for holding
A system of weights, cords and/or coiled springs which assist in raising
double-hung sash and tend to keep the sash in any placed position by
counterbalancing the weight of the sash.
In double-hung windows, the rope or chain which attaches the sash to the
A protruding handle screwed to the inside bottom rail of the lower sash
on a double-hung window.
In older double-hung windows, the concealed cast-iron weights which are
used to counterbalance the sash.
A flat board cut to fit the contour of a bow or bay window and installed
between the sills and the flat wall surface, providing a seat or shelf
Wood wedges (often wood shingles) used to secure the window or door unit
in the rough or masonry opening in a square, level and plumb position
during and after installation.
The main horizontal member forming the bottom of the frame of a window
A method of constructing windows in which muntins are affixed to the
inside and outside of a panel of insulating glass to simulate the look
of true divided light.
Use of single panes of glass in a window. Not as energy-efficient as
A double-hung type of window in which the top sash is fixed or
Used to cover the gap between the old sloped sill window and the new
block frame window. It adapts a new window to the existing sloping sill.
The process of providing a net heat gain within a structure, over and
above the normal heat loss, by passive collection of the sun's heat
through windows and other glazed areas.
The main vertical members of the framework of a sash.
An interior trim piece on a window which extends the sill and acts as a
A molding used to hold, position or separate window parts.
Glass manufactured to withstand greater than normal forces on its
surface. When it breaks, it shatters into small pieces to reduce hazard.
A rectangular projection cut out of a piece of wood for insertion into a
The addition of a thermal insulating material between two thermally
A small window that fits over the top of a door or window, primarily for
additional light and aesthetic value.
A term which refers to windows in which multiple individual panes of
glass or lights are assembled in the sash using muntins.
Rate of heat flow-value through the complete heat barrier, from room air
to outside air. The lower the U-value, the better the insulating value.
A casement locking system which secures the window at two locking points
by operation of one handle.
A window or door unit that opens or operates.
A plastic material used for cladding or entire window units.
A material or device used to seal the openings, gaps or cracks of
venting window and door units to prevent water and air infiltration.
Force exerted on a surface by moving air.