Argon Gas - A colorless and odorless gas used to fill the airspace between panes of insulating glass. The addition of argon gas greatly increases the thermal performance of a window by minimizing heat transfer.

Cladding - A protective shield on the exterior of windows and doors.  Marvin's clad exterior is made of extruded aluminum with a thick, durable finish.

Combination Storm - A wood or aluminum storm sash with self-storing screen and operating glass panels. Available for double hungs, gliders and wood swinging doors, these panels are removable.

Divided Lites - Division of light by the use of muntin bars.

• Muntins: The actual bars that create a pattern in the window.

• Authentic Divided Lites (ADLs): Single or insulating glass, individually glazed between the muntin bars.

• Simulated Divided Lites (SDLs): Muntins permanently adhered to the interior and exterior of the glass.

• Grilles: Wood Muntins fastened to the interior of the sash to create the effect of divided lites, removable for easy glass cleaning.

• Space Bar: Tiny aluminum bars inserted between SDL muntins to emulate ADL.

Frame - The stationary portion of a window installed into the rough opening in a wall, enclosing the sash (operating and/or stationary), consisting of the following parts:

• Header: The horizontal top of the frame.

• Jamb: The left or right vertical side of the frame.

• Sill: The horizontal bottom of the frame.

• Brick Mould or Flat Casing: The exterior trim applied to the side jambs and header on wood and clad units.

Glazing: The actual glass installed in a window or door.  Can be either single with one sheet of glass or insulated by using two sheets of glass. 

Low E II Glass - Low E stands for "low emissivity" and is designed to improve thermal performance by reflecting or absorbing the sun's warmth, as well as reducing the damage from UV rays.

Mulling - The act of attaching two or more windows or a door and
transom units together.

R-Value - The resistance a material has to heat flow. Higher numbers indicate greater insulating capabilities.

Rough Opening - The hole in the wall where a window or door unit will be installed. Openings are larger than unit size to allow room for insulation and shimming the unit square.

Sash - The glass-and-wood operating or stationary portion of a window, separate from the frame. The sash consists of the following:

• Stiles: Vertical sides of window sash.

• Rails: Horizontal sides of the sash.

• Check Rails: Horizontal sides of the sash that meet, such as at the center of double hungs, or where vertical stiles meet, as in the glider.

Transom - A stationary or operating window directly above a window or door.

U-Factor - A measure of total heat flow through a window or door barrier from room air to outside air. Lower numbers indicate greater insulating capabilities.