Window and Sash Terminology

SASH OPENING: The Width and Height of the window FRAME opening that the sash fit into.  For Double-Hung windows, the sash opening width is measured between the pulley stiles.  The sash opening height is measured from the underside of the head to the sill at the outside of the lower sash channel, or inside edge of the parting stop.

SASH THICKNESS: Self-explanitory, except on CHECK-RAIL windows.  The sash thickness is NOT determined by the thickness of the check-rails, as the check-rails are typically about 3/8" thicker than the actual sash thickness.  Standard sash thicknesses are 1-1/8", 1-3/8", and 1-3/4".  Other thicknesses are specials.

DAYLIGHT OPENING: The area of glass visible in a glazed sash.  The GLASS SIZE is usually 5/16" wider and 5/16" higher than the daylight opening.  Exceptions to this rule for special SASH STICKING profiles, and also for WESTERN STANDARD sash which have a 1/4" wide glass rabbet, so Western sash have a glass size 7/16" larger than the daylight opening.

SASH STICKING: The inner arris of the sash is moulded with a profile on the interior edge and a GLASS RABBET on the exterior edge to receive the glass.

GLASS RABBET: The rabbet on the exterior face of the inner arris of the sash ploughed to receive the glass.  Standard glass rabbets are 3/16" wide by 3/8" to 5/8" deep, depending on the sash thickness.  Western standard sash have 1/4" wide glass rabbets.  SASH BARS and MUNTINS have glass rabbets ploughed on both edges of the exterior face to receive glass.

SASH BAR: A narrow glazing bar in a sash for the purpose of cutting  the sash into multiple or DIVIDED LIGHTS.  A sash bar can either be a structural part of the sash or a muntin.

MUNTIN: A short sash bar that terminates at each end at the STILES, RAILS, or other SASH BARS but does not run through the joint.  A muntin is not a structural member of the sash and is either coped or stub-tenoned and coped at its ends.

DIVIDED LIGHT SASH: A sash cut up into multiple lights by the addition of sash bars. Common divided-light sash patterns are 2-light (Victorian), 4-light, 6-light, 8-light, and 12-light.  Endless arrangements are possible, for example marginal-light sash and sash with diagonal sash bars such as diamond-light sash.