Small honeycomb spaces within the sash
and frame which help to insulate and
strengthen the window
The 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
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 ventilation.
Device 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.
A composite of four or more window units in
a radial or bow formation.
A small metal tube that is placed into an
insulated unit's spacer to equalize pressure
differences. Breather tubes can allow
moisture to enter into the insulating unit.
Mostly used in high altitude locations.
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 position.
A window unit in which the single sash
cranks outward, to the right or left.
Molding of various widths, thickness and
shapes applied to the framework of window
and door units.
Any material locked to the outside faces of
doors and windows to provide a durable,
low-maintenance exterior surface.
A window unit that has two operable sashes
which move vertically in the frame.
A form produced by forcing material through
a die. Most window frames are clad with
extruded vinyl or aluminum.
Non-venting or non-operable window. Also
known as picture window.
Foam material placed in the airspace of the
insulating glass in a window to enhance the
appearance and improve the performance of
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 window unit in which the top of the sash
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
The main vertical members forming the sides
of a window or door frame.
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.
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 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 grids.
A framed sheet of glass within a window.
Non-venting or non-operable window. Also
know as a fixed window.
Resistance to thermal transfer or heat flow.
Higher R-value numbers indicate greater
A single assembly of stiles and rails made
into a frame for holding glass.
Narrow fixed units mulled or joined to door
units to give a more open appearance.
A double-hung type of window in which the
top sash is fixed or inoperable.
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
Glass manufactured to withstand greater than
normal forces on its surface. When it
breaks, it shatters into small pieces to
reduce hazard. Standard on all doors and
large fixed windows.
A small window that fits over the top of a
door or window, primarily for additional
light and aesthetic value.
Rate of heat flow-value through the complete
heat barrier, from room air to outside air.
The lower the U-value, the better the
A window or door unit that opens or
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