Window Jamb and Sill Restoration
Restoring Window Jambs and Sills is Essential to Achieving Lead-free and Smooth Operation
The Difference Between A Window Frame & A Window Jamb
The window jamb is different from the window frame. The interior frame is the part that sits flush with the interior wall. Correspondingly, there is an exterior frame that fits flush with the exterior wall. They frame the window opening (defined as the cavity in the wall into which a window is set).
The window jamb is the space between these two frames. It forms the side walls (or side jambs) that the sashes ride up and down against when the window is opened or closed. When the top sash is raised up to its closed position, it rests against the header jamb. At the bottom of this opening is the window sill.
Full Window Restoration Necessarily Includes The Jamb, the Sill, the Stops, and the Parting Bead
Below Are Five Reasons Why:
Because the sashes brush up against the jamb, the stops, and the parting beads when opened or closed, they act like sandpaper, potentially creating hazardous lead paint dust that had improperly been slathered on the sides of the stops and jamb walls.
Because this movement causes friction between the sashes and the painted edges of the stops and jamb walls, the windows cannot operate smoothly. Oftentimes these layers of paint are so thick as to render the window completely inoperable!
Paint removal is crucial for fitting and shimming the interlocking weather seals in our restoration process. The goal is to allow enough room for sash movement without causing rattling or letting air and moisture in. A tight, precise fit ensures smooth movement and weather resistance.
Neglect of rot in the sills and damage to the pocket doors in the jamb walls (behind which the sash weights fit) can lead to rot of the interior of the wall beneath the sill.
As can be seen in the before photo, most original window jambs have thick layers of cracking paint. See how beautiful the window looks when it has been removed?
The Jamb & Sill Are Often Overlooked
Given these concerns, one wonders why jamb and sill restoration is the most often neglected part of the window restoration process. One cannot restore—as in, bring the whole element back as close to the original condition as possible—without restoring these parts of the window.
But with results like this, one wonders why anyone would neglect this important aspect of the process. And they function as smoothly as they appear beautiful. This integration of function and beauty is a bedrock value undergirding all our work.