Window Anatomy

Parts of a Window: Terms and definition for Pella Windows
From inspiration to installation, everything starts here.

Knowing the right names for parts of your window can help you avoid confusion.

The window industry has its own language for things, as you might expect. Window manufacturers, window installers, and contractors may all speak to you using a variety of terms.

Learn how Pella defines window parts and components.

Looking for replacement parts?

Visit the Pella Replacement Parts Store

Exterior Parts of a Double-Hung Window

Exterior Parts of a Architect Series Double-Hung Window
  • Frame
    The framework that surrounds and supports the entire window system – comprised of the head, jamb and sill.
  • Head
    The main horizontal part forming the top of the window frame.
  • Jambs
    The main vertical parts forming the sides of a window frame.
  • Sill
    The main horizontal part forming the bottom of the frame of a window.
  • Jambliner
    A strip which goes on the sides of a window frame that provides a snug fit for the window sash.

Hardware and Interior Parts of a Double-Hung Window

Hardware & Interior Parts of a Double-Hung Window
  • Balance (Not shown)
    A mechanical device (normally spring loaded) used in single- and double-hung windows as a means of counterbalancing the weight of the sash during opening and closing.
  • Sash
    The movable part of a window made up of the vertical and horizontal frame that holds the glass.
  • Check Rail
    On a double-hung window, the part where the bottom part of the upper sash and the upper part of the lower sash come in contact. Also known as the middle of the window.
  • Glass
    A framed sheet of glass within a window frame.
  • Rail
    The horizontal piece of a window sash – comprised of the lower rail and upper rail.
  • Lower Rail
  • Upper Rail
  • Lift
    A handle for raising the lower sash in a single- or double-hung window.
  • Sash Lock
    The locking mechanism used on a single- or double-hung window that engages with the sash lock strike to reduce rattling.

Parts of a Casement Window

Parts of a Casement Window
  • Aluminum Clad
    The exterior wood parts of a window covered with extruded aluminum, with a factory-applied finish to deter the elements.
  • Argon (Not shown)
    An inert, nontoxic gas used in insulating glass units to reduce heat transfer.
  • Casing
    Decorative molding or framing around a window that opens inward to allow access to our snap-in, between-the-glass blinds, shades and grilles.
  • Hinged Glass Panel
    The glass panel on the windows that opens inward to allow access to our snap-in, between-the-glass blinds, shades and grilles.
  • Lock Handle
    A locking mechanism located on the jamb of a window.
  • Operator
    A crank-operated device for opening and closing casement or awning windows.
  • Weatherstrip (Not shown)
    A strip of resilient material for covering the joint between the window sash and frame in order to reduce air leaks and prevent water from entering the structure.

Hardware and Interior Parts of a Double-Hung Window with Circlehead

Hardware & Interior Parts of a Double-Hung Window with Circlehead
  • Fixed Panel
    An inoperable panel of a window.
  • Mullion
    A major structural vertical or horizontal piece that combines two or more windows together.
  • Grilles
    Decorative pieces that visually divide window panels, giving the glass the appearance of multiple glass panes.

Exterior Parts of a Double-Hung Window with Circlehead

Exterior Parts of a Double-Hung Window with Circlehead
  • Mullion
    A major structural vertical or horizontal piece that combines two or more windows together.
  • Screen
    Woven mesh of metal, plastic, or fiberglass stretched over a window opening to permit air to pass through, but not insects.
  • Weep Hole
    The individual openings provided in the window sill that allow water or condensation to escape.

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Door Anatomy