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 I need jamb extensions?
Without jamb extensions, a skilled trim carpenter or drywall installer is required to fill the unrequited space with wood, drywall, or another material before the window can be trimmed, so having jamb extensions applied by the window manufacturer can save labor expenses on the jobsite.
Can you use plywood for window jambs?
The jambs for each window are made from 3/4″ paint grade plywood. Using plywood will eliminate any possibility of seasonal expansion and contraction that is a problem with wider pieces of solid wood. It’s also less expensive, stays flat and is very durable.
How thick is a window jamb?
Jambs: The vertical members of the window frame, thicker jambs provide better overall performance of the operating parts of the window called the “sash.” Building-grade windows have jambs from 2-7/16 to 3 inches thick, while premium grade windows offer 3-1/4 inch jambs.
Where are window jambs located?
Jambs are the main vertical parts forming the sides of a window frame. A sill is the main horizontal part forming the bottom of the frame of a window. A jambliner is a strip which goes on the sides of a window frame that provides a snug fit for the window sash.
What is the jamb depth of a window?
Measure the window jamb’s depth. This will be from where the exterior brick mold is attached to the window across to where the interior window trim attaches to the jamb. This is normally 4 9/16 or 6 9/16 inches deep.
What wood is used for window jambs?
For jamb extensions, I’ll always use wood (pine/poplar) over mdf, as the tiniest bit of moisture on mdf will swell it like old cardboard. Be sure to prime every side of the wood (including cut ends) before installation. You shouldn’t try to have a gap between the extension and the window.
What are jamb installation clips?
The clips stop the Jamb Extension from bowing when foam or fiberglass insulation is applied and there are no insulation voids. Install 1/2″ screws to the Jamb Extension and 2″ screws into the wall framing making sure the Jamb Extension is plumb.
What is a window jamb and casing?
Vocabulary: Extension jamb: Lengths of wood that build out a window frame flush with the interior wall surface. Casing: Material that finishes the joint between the extension jambs and the interior walls.
What are window jambs made of?
The material used to make a window jamb can vary, and may be wood, plastic, vinyl, or metal. Window jambs may be painted to match the trim on a structure, or left unfinished, depending on the material and the aesthetics of the structure.
