Wisconsin’s Best Window Glossary

Milwaukee Window and Door Installation Glossary

To ensure you fully understand everything you need to know about your professional Milwaukee replacement windows and our replacement window and door installation services, Infinity Exteriors has provided you with a glossary of all the common and not so common window terms and definitions. We want to make sure you are fully educated and able to make the best possible decision when it comes to your Milwaukee or Waukesha replacement window or door installation services. Reference this alphabetical replacement window and installation glossary for any further information or definitions you need while choosing the best replacement window options for you!



American Architectural Manufacturers Association. The AAMA is a national trade association establishing ideal standards for window, door, skylight and other industries of the like.


A weather and shatter resistant thermoplastic with good optical clarity used for glazing.

Air Infiltration

The measured amount of air leaking in or out of a home or building through cracks in the windows, doors, and walls. (Also referred to as Air Leakage)

Air-leakage Rating

The measure of the air-leakage rate around a door, window, or skylight when a specific pressure difference is present. The lower the air-leakage rating of a window, the better the airtightness. 

Annealed Glass

A standard float glass sheet that has not been heat-treated.


The use of heat above the critical temperature followed by the controlled cooling of glass, metal, and other materials, relieving internal stresses, eliminating the effects of cold-working, and improving ductility, strength, and other properties.  


American National Standards Institute, the official clearing house for standards and specifications of all types.


A nontoxic, inert gas used in the insulation of glass units to reduce heat transfer.


American Society for Testing and Materials, an organization setting standards for the testing of materials.

Awning Window

Casement window where the sash is hinged at the top and always swings outward.


A mechanical device that is typically spring-loaded used to counterbalance the weight of the window sash when opening and closing single and double-hung windows.

Bay Window

Three or more windows designed and arranged specially to provide more light, and commonly projecting from the house to create more room and a widened view. Also, see Bow Windows.

Bead (Bead Stop)

The wooden strip a swinging window sash, such as with a casement window, closes against. This also refers to the finishing trim used at the top and sides of the frame to hold a fixed sash.   

Bottom Rail

The horizontal member at the bottom of a window sash.

Bow Window

A rounded version of a Bay Window, projecting from your home or building in an arced shape, and commonly consisting of five or more window sashes.

Brick Molding

The standard wooden trim piece, covering the gap between your window frame and masonry. 

Casement Window

A common window sash that swings open on side hinges.


The exposed framing or molding around your window or door, present on either the inside or outside, covering and protecting the space between the frame and the wall.


A compound used for sealing and filling joints and cracks, preventing leakage of air or water. Caulking is commonly made of silicone, acrylic, bituminous, or rubber-based materials.

Check Rail

The connecting bottom horizontal member of the upper sash and top horizontal member of the lower sash in the middle of a double-hung window.


A window that is placed higher up in a lofty room, admitting extra light toward the center of the room.

Composite Frame

A window frame that consists of two or more materials. (ie, interior wood and exterior fiberglass)


Water vapor from the air that can deposit on cold window glass or a window frame exposed to humid air.

Condensation Resistance Factor (CRF)

A measure of your window’s ability to resist condensation. This is based on an AAMA standard concluding the higher the CRF, the less likely condensation issues will occur.


A porous crystalline substance for absorbing moisture within a sealed air space of an insulating glass unit.


Water vapor in air will condense at this temperature with a given state of pressure and humidity.

Divided Light

A window with multiple smaller glass window panes separated and held in place with a secondary framing member referred to as a muntin.

Double-Hung Window

A window featuring both an upper and lower window sash that can be slid up and down pas one another within a single casement.

Double-Strength Glass

Sheet glass that is between 0.115” and 0.133” (33.38 mm) thick.  


Optical properties used with glazing that are variable from dark to clear with a low-voltage signal. Optical density changes by removing or reversibly injecting ions from an electro chromic material.

Electromagnetic Spectrum

A broad range of radiant energy over wavelengths.

Emergency Exit Window

(Egress window) A fire escape window of large enough size for a person to climb out in the case of an emergency. Each bedroom of a home must have an exit window according U.S. building codes.


Under the same conditions and at the same temp, this is the ratio of radiant flux emitted by a specimen to the radian flux emitted by a blackbody.

Exterior Stop

The removable molding or glazing bead used on the exterior side of the panel to hold your window panel or glass in place.


The process of forcing heated material through an orifice in a die to produce vinyl or aluminum. Also used to refer to any item produced by this process.

Eyebrow Windows

(“attic windows”) Low windows opening inward with a bottom-hinged sash. They are sometimes called “slave window”.


A half-circle shaped window with radiating or fanning bars, usually above a door or window.


Important in the control of a home or building’s exterior appearance, this is the placement of your window openings in a wall. This also refers to a door, window, or skylight and its associated exterior or interior (shades, blinds, etc.).


A composite material of embedded glass fibers in a polymer matrix. Fiberglass can be used in sheet form as a diffusing material, or as a sash and frame element.

Fixed light

The space in a non-operating frame for a pane of glass, or a window pane of glass installed within a non-operating framing member. (Does not move, open, or close)

Fixed Panel

The panel or a sliding glass door or slider window that is stays in place.

Fixed Window

An inoperable window.

Float Glass

The process of forming glass by floating the material on a bed of molten metal. The outcome of this is high-optical-quality parallel surfaced glass without the need to polish or grind.


Caused by failing seals or temperature extremes, this is contamination on the inside surface of a sealed insulating glass unit.


The fixed window casing or border holding the window sash or casement and hardware.


A transparent material made of silica, sodium carbonate, calcium carbonate, and small amounts of alumina, boric, or magnesia oxides.


Plastic or glass panes within a door, window, or skylight.

Glazing Bead

A stop or a molding to hold the glass in place inside of a window frame.

Greenhouse Window

A window that is 3-dimensional and projects from exterior of your home or building. These windows typically have glazing on all sides with exception to the bottom which is usually used as a shelf.


The horizontal part at the top of a window frame.

Heat-absorbing Glass

Window glass that contains chemicals to reduces the glare and brightness and absorbs light and heat radiation. This glass usually has a gray, bronze, or blue-green tint.

Heat Gain

The heat transfer from outside to inside the house or building through conduction, convection, and radiation throughout all surfaces within a house or building.

Heat Loss

The opposite of heat gain, the heat transfer from inside to outside the house or building through conduction, convection, and radiation throughout all surfaces within a house or building.

Heat-strengthened Glass

Glass that, after it is formed, is reheated to just below the melting point, and then cooled. This forms a compressed surface increasing the strength more so than regular annealed glass.

Hinged Windows

Casement, awning or hopper windows with an operable sash having hinges on one side.


Window with its sash hinged at the bottom.

Horizontal Slider

A window incorporating a movable panel that slides from side to side.

International Code Council (ICC)

A national organization publishing model codes for states and other agencies to adopt. These codes include the International Building Code (IBC) and the International Energy Conservation Code (IECC).

International Energy Conservation Code (IECC)

Code published by the ICC. This is the successor of the Model Energy Code cited in the 1992 U.S. Energy Policy Act as the baseline for residential energy codes in the U.S.

Infrared Radiation

Electromagnetic radiation that is invisible and beyond red light on the spectrum.

Insulated Shutters

Panels for insulation that cover a windows opening, reducing heat loss.

Insulating Glass

Multiple pieces of glass spaced apart and sealed to form a single glazed unit with air space or spaces between. (also referred to as double glazing)


Materials used for protection against heat, cold, fire, or noise.

Interior Stop

The opposite of an exterior stop, the removable molding or glazing bead used on the interior side of the glass to hold your window panel or glass in place.


A frame member of a panel in a sliding glass door that is upright and engages with a agreeing member in an end-to-end panel when the door is close. (interlocking stile)


A vertical part at the side of your window frame, or a horizontal part at the top of your window frame.  (ie. Head jamb)


A nontoxic gas used for window insulation to reduce heat transfer.

Laminated Glass

Multiple sheets of glass that incorporate a layer of transparent plastic to which the glass adheres if broken. This is typically used for safety glazing and the reduction of sound.


The handle used for raising the lower sash within a double-hung window. Can also be referred to as a sash lift.


 – A window or a pane of glass within a window.

Light-to-solar-gain ratio (LSG)

Measures a glazing’s ability to provide light without too much solar heat gain. This is the ratio between a glazing’s visible transmittance and its solar heat gain coefficient.


A horizontal piece above a window or door opening supporting the structure above.

Long-Conductance Spacers

Materials designed to reduce potential heat transfer at the edge of an insulating window. These spacers are typically placed between the window panes within a double or triple glazed window.

Low-Emittance Coating (Low – E)

Extremely thin, virtually invisible metal or metallic oxide layers deposited on a window or skylight glazing surface. These are primarily used to reduce the U-factor by the suppression of radiative heat flow.

Meeting Rail

Where two panels meet and create a weather barrier in a sliding glass door, sliding window, or a hung window.


A structural vertical or horizontal unit between window units or sliding glass doors.


A horizontal, vertical, or diagonal secondary framing member to hold the window panes in the sash.

Muntin Grilles

Removable wood, plastic, or metal grids designed to give the appearance of muntins in a multi-light sash for a single-light sash.


National Fenestration Rating Council

Obscure Glass

Textured glass used for privacy, light diffusion, or decorative effects. Examples include frosted, etched, fluted, ground, etc.

Operable Window

A window that can be opened and closed.


Crank operated device used for opening and closing casement windows.


A sheet of glass or a compartment of a window or door that consists of a single sheet of glass in a frame.


A light of glass in a frame installed within the outer frame of the door. This is a major component of a sliding glass door, and can be fixed or sliding.


Used to cover the old window material, the aluminum trim that can extend around the perimeter of the window opening.

Parting Stop

An integral or applied narrow strip holding a sash or window panel in position within the frame.

Picture Window

A fixed window that is often longer horizontally than vertically, providing a panoramic view. These windows are usually quite large.

Pivot Window

A window that has an operable sash that swings open or shut by revolving on pivots on any side of the sash.


An artificial substance of organic polymers. Plastic can be molded or stretched in to various shapes including window sashes and frames.

Polyvinylchloride (PVC)

 A stretched or molded plastic material for window framing or used as a thermal barrier with aluminum windows.

Projected Window

An operable window with one or more sashes opening on hinges or pivoted arms


The heat transfer in the form of electromagnetic waves from one surface to another. A person can lose body heat to a cold window or surface.


Horizontal unit of a window sash.


The ratio of reflected radiant energy to incident radiant energy.


A light ray deflected from a straight path when it passes at an oblique angle from one medium to another.


The addition or replacement of items on an existing home or building. This includes replacement windows and doors, insulation, caulking, storm windows, vents, and landscaping.

Roof Window

An operable or fixed window in the sloping surface of a roof.

Rough Opening

The opening in a wall where a door or window will be installed.

Safety Glass

Glass that is strengthened or reinforced and less likely to break or splinter.


The part of a window that includes the framing sections directly attached to the glass and the glass itself.


Woven mesh material consisting of metal, plastic, or fiberglass that permits air to pass through but keeps out insects and other debris.

Sheet Glass

Flat, transparent glass found mostly in older windows.


The lowest horizontal unit of a door window or sash frame.

Single Glazing

A single thickness of glass in a window or door.

Single-hung Window

A window with 2 glass sashes, with the top one being stationary and the bottom operable.

Single-Strength Glass

Glass with a thickness between 0.085” and 0.100” (2.162.57 mm)


A window in the roof that gives added light and ventilation.

Sliding Glass Door

A door that has one or more panels fitted and move or open horizontally on a track.

Sliding Window

A window that has one or more sashes that open by sliding horizontally or vertically in grooves or tracks provided by frame units.

Smart Window

Term used to describe windows with switchable coatings controlling solar gain.

Solar Control Coatings

Coatings of thin film on glass or plastic, absorbing or reflecting solar energy and reducing solar gain.

Solar Radiation

The total radiant energy from the sun.

Solar Screen

Screens, panels, or blinds used as a sun shading device, intercepting solar radiation.

Solar Spectrum

The spectral range or the intensity of sunlight variation.

Sound Transmission Class (STC)

The rating of the sound transmission loss of a material over a selected range or frequencies.


The vertical edges of a window, screen, or door.


A board in the interior or a window sill where the bottom rail of the sash closes against.

Storm Windows

A secondary set of windows on either the outside or inside of primary windows, providing additional insulation and protection.

Tempered Glass

Strengthened, treated glass. This glass is up to 5 times stronger than regular annealed glass.


Glazing with the use of optical properties able to change in response to temperature changes.


A unit lying at the bottom of a swinging or sliding glass door. (the sill of a doorway)

Tilt Window

An operable single or double-hung window that can be tilted towards the interior.


Sliding unit allowing you to open and close a door or window with ease.


Uniform Building Code


Movable sash or framework in a hinged or pivoted to swing open window.


Polyvinyl chloride material, either ridged or flexible, commonly used for window frames.

Vinyl-Clad Window

A window that has exterior wood parts with an extruded vinyl covering


Resilient material used to cover the joint between a window sash and the frame, reducing air leaks and preventing the entrance of water.

Weep Hole

A smaller external opening in the wall of a building allowing water to drain to the building exterior.


A glass or plastic opening in an external wall of a building or home.

Contact Infinity Exteriors today  to learn more about the best value, best performance, custom replacement windows in Milwaukee Waukesha – Brookfield - New Berlin - Racine – Wauwatosa - West Allis - Shorewood Pewaukee - Oconomowoc - WhitefishBay - Hartland - Franklin - Kenosha - Muskego - Oak CreekDelafield - Elm Grove - Menomonee Falls - Pleasant Prairie - Greenfield - CudahyGermantown - Green Bay - Port Washington -Madison- Mukwonago -Grafton - Appleton.