What is a jamb extension? A window jamb extension is an interior window component (in varying depths) that allows the window frame to fit the window opening. They can be included as an attachment as in the case of most window replacement projects, or they can be retrofit after the window frame has been installed.

What does a door jamb extension do?

Interior extension jambs are added to the inside edge of window and patio door unit frames to create a consistent transition between the window unit and interior trim/casing. They are available in a range of depths to accommodate different window jamb dimensions and wall thickness.

Do Windows come with jamb extensions?

They can be included as an attachment as in the case of most window replacement projects, or they can be retrofit after the window frame has been installed. Jamb extensions reach out from the jamb from the top, sides and bottom (in most cases, depending on finishing requirements) of the window.