Glossary of Terms

The area between two or more sheets of glass in a window or door.

Airspace Grilles (or Grilles in the Airspace)
Aluminum bars sealed in the insulating airspace between the two panes of glass in a window or door.

Awning Window
A single-sash window that’s hinged at the top of the sash and uses a handle crank that allows the bottom of the window to swing out towards the exterior of a home.

A system used in double- or single-hung tilt windows that holds the operating sash open in any position and allows the window to be opened or closed with minimal effort.

Bay Window
A picture window combination consisting of two or more windows placed at 30-, 45- or 90-degree angles allowing it to extend outside a home’s exterior and create an open space on the interior. The individual units in a bay window usually feature both fixed and operating sash.

Bottom Sweep
A specially designed, flexible fin attached along the bottom of a door to create a tight seal when the door is closed to prevent air and water from entering a home.

Bow Bay
A bay window combination featuring a series of four or more windows gently angled to create a curved shape that extends outside a home’s exterior. Generally, the individual window units on the far ends feature an operating sash.

Box Bay
A bay window combination featuring two sash set at a 90-degree angle.

Brick Mould
The decorative moulding surrounding the exterior of a window or door frame to provide them with the traditional look of a wood window or door.

Space between patio door panels that provides a contemporary profile and improved sight lines

The ornamental material used to hold decorative pieces of glass in place. Caming is typically made from brass, lead or zinc in a variety of finishes.

Casement Window
A single-sash window that’s hinged on one side and uses a handle crank that allows the window to swing open to either the right or the left, towards the exterior of a home.

Check Rail (or meeting rail)
The horizontal sash members on a double- or single-hung tilt window or the vertical sash members on a slide/by window that come together when the windows are closed.

Circle Top (or round top)
A direct-set window in the shape of a quarter circle, a half circle, a half ellipse, an arch top, a full ellipse, a full circle or a gothic arch top that can be used alone, in combination or stacked above another window or door.

Refers to the portion of a wood window or door that’s covered with aluminum, fiberglass or vinyl on the exterior side of the frame and/or sash. Weather Shield uses a composite sash construction system where extruded aluminum, pultruded fiberglass or vinyl exteriors are bonded to solid wood interiors by means of a mechanical and chemical interlock system.

Moisture that forms on a surface. This could be a result of a difference in temperature or an excess of humidity between the surface and the air.

A material used in Weather Shield window and door spacer bars that absorbs water and helps remove moisture.

A sash-less window that doesn’t open and features the glass glazed directly into the window frame. A direct-set picture window can also feature a simulated sash designed to match the look of a unit with operating sash.

Door Panels
The swinging or sliding portion of a patio door, consisting of the top and bottom horizontal rails, the left and right vertical stiles and the glass.

Door Rollers
Two sets of tandem stainless steel wheels with ball bearings that allow sliding patio doors to smoothly open and close using the minimum of effort.

Double Hung Tilt
A window where both the upper and lower sash slide up and down to allow air into the room. The sash are designed to tilt into a room for easy removal or cleaning on both sides from inside a home.

Double Slider (Double-Slide/By)
A window where both sash open and close by sliding sideways.

Drip Cap
A formed aluminum or vinyl accessory piece that’s installed along the top of clad windows and doors that allows water to run off of the unit instead of seeping into the unit and a home.

A process of gluing separate wood pieces together, usually across the grain, in order to make a wider or thicker piece of lumber that helps minimize bowing and warping.

A round top window consisting of a partial radius head that’s typically used above a tilt window, casement window or French door.

The surrounding outside portion of a window or door composed of the head at the top, the side jambs and the sill at the bottom.

The glass portion of a window or door. Also refers to the actual process of installing the glass in a sash, frame or door panel.

A decorative pattern on a window or door consisting of horizontal and/or vertical bars that divide the larger sheet of glass into smaller panes.

The locks, crank handles and hinges on windows and doors used to operate and secure them.

The horizontal piece forming the top of the frame on a window or door.

The hardware portion of a window or door that allows the window sash or door panel to open.

Jamb (or Side Jamb)
The left and right vertical pieces forming the frame on a window or door.

Jamb Extension
An extra window frame piece added to the jamb that extends the frame to match the precise thickness of a wall.

Jamb Liner
The tracks located inside the jambs of a double- and single-hung window on which the sash slide up and down.

An accessory that attaches to a window for a finished edge where exterior siding is used.

A door’s complete lock system consisting of the lock mechanism, knobs, keys, plates, strikes and other accessories.

Low E
A term meaning low “emissivity”. Emissivity is a property that’s unique to materials such as glass, which light can freely pass through. Low describes the filtering out of the part of the light spectrum that transmits heat.

Low E Glass
Glass with a microscopic coating applied to one or more surfaces to provide greater energy efficiency and UV protection that helps reduce the fading of artwork, curtains, furniture, rugs and floors in a home.

Mull (or Mulling)
The actual piece used to attach two or more window and/or door units together to form a combination. The process of joining the units to each other.

Mull Cover
An exterior connector that joins two windows together with a finished edge to cover the space between two units. It also helps prevent a

Nailing Fin

A single piece of glass within a window or door.

Picture Sliding Patio Doors
A large, stationary picture window glass panel flanked by one or two sliding panel doors that slide in front of the picture window panel to give sweeping views.

Picture Window
A stationary window used to capture wide views of exterior landscape. Can be combined with other functional windows such as double hungs and casements, and/or topped with direct set or awning windows for enhanced views.

The horizontal framework members of a window sash or door panel.

Rough Opening
The opening in the wall where the window or door is to be installed, slightly larger than the size of the unit to allow squaring and shimming.

A measurement of how much a material resists heat transfer. A higher R-Value means a greater insulating effect and a lower rate of heat flow out of the home.

The fixed or operating portion of the window consisting of top and bottom horizontal rails, left and right vertical stiles, and the glass.

Sash Lock
The piece of window hardware that secures the sash to the frame on a casement or awning window, or secures two sash at the check rail on a tilt or slide/by window, when the window is closed.

The framed, mesh fiberglass exterior piece on a window or door that keeps insects from entering the home.

Side Jamb
The vertical left and right members of a frame on a window or door.

The horizontal piece forming the bottom of the frame on a window or door.

Simulated Divided Lites (or SDL)
Windows with grilles adhered to the interior and exterior of the window glass, in a variety of decorative options, to simulate the look of true divided lites.

Single Hung
A window with two sash, where the bottom sash slides up and down and the top sash is fixed. Many single hung windows also have a tilt-in option on the bottom sash for easy cleaning and removal.

Slider (or slide by)
Windows that slide open horizontally. Available in single, double and triple units.

Sliding Patio Door
Up to four glass door panels that slide on tracks giving fast, easy access to the outdoors. (Also see Telescoping Patio Doors)

Solar Heat Gain Coefficient (SHGC)
Measures how well a window or door prevents heat from passing through it. The lower a window or door’s SHGC, the less heat it allows to pass through it.

An anodized aluminum bar used to separate the panes of glass in an insulating window.

When two or more window units are joined vertically.

A non-operating sash, panel or unit.

Moulding set in place to hold, position or separate window parts.

A piece of vinyl weather stripping along the bottom of the door that makes contact with the threshold to provide a tight seal against air and water infiltration.

Tempered Glass
Float glass that is heated and then cooled rapidly to make it several times stronger than annealed glass. Standard in all Weather Shield doors, tempered glass is safer than annealed glass because when it is broken it falls into pebble-like pieces without sharp edges.

The bottom area of the door frame that you step over when entering or exiting through a doorway.

Both sash of this window slide up and down to allow air into the room, as well as tilt into a room for easy cleaning on both sides.

A window stacked above another window or door.

Triple Slider (or Triple Slider)
A three sash window featuring a stationary center sash and two flanking sash that open and close by sliding sideways.

A measurement of how much energy a material conducts. The lower the U-Value, the greater the insulating effect.

Warm Edge Spacer
Refers to the type of spacer material used to separate panes of glass in an insulated window unit. If the material conducts less heat or cold than an aluminum spacer at the edge of the glass, it is said to be “warm edge”.

Weather Stripping
A strip of resilient material designed to seal the sash and frame members to reduce air and water infiltration.

Weep System

A special interior formation of the sill designed to channel water away from your home to prevent the moisture build-up that leads to rotting.