J-channel A J-channel is a space that allows a home’s siding to slip between the trim and nailing fin. This feature also allows for easy installation and produces a clean, streamlined appearance.
	Jalousie A series of small horizontal overlapping glass slats held together by a metal end frame attached to the faces of the window frame side jambs or door stiles and rails.
	Jamb The vertical frame members of a window or door assembly.
	Jamb adjuster (jamb jack) These are adjustable screws that are designed for mounting window and door frames into rough openings. They are used to help ensure the product is squarely installed.
	Jamb depth This is the measurement from the outside of the exterior sheathing to the inside of the drywall.
	Jamb extension This is a jamb-like component that extends the depth of a window or door frame. In general, a jamb extension has a larger depth than a jamb liner.
	Jamb liner This is the component that covers the inside surface and head jambs of a window.
	Jamb liner clutch A jamb liner clutch is the part of the balance system into which the cam pivot is inserted or engaged. Also referred to as a terminal block.
	Jamb size See jamb depth.
	Joint The joining of two pieces of wood by nails, glue, adhesives or other means; joints may be joined end to end, edge to edge, end to edge, or end to face.
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