CAUTION: Do not remove the old window or wood sash until you verify that the dimensions of the new replacement window unit are correct.
Preparation of the Opening
- Remove the old sashes by removing the interior and/or parting stops, metal jamb liners, sash counterweights, etc. on the sides and top of the opening, being careful not to damage the structure. Do not remover the exterior stop. Remove old sash counterweights if possible and insulate the counterweight pocket with fiberglass batt insulation.
- Clean and remove any peeling paint or debris from the window opening, especially on the inside of the exterior stop.
- Make sure the opening is level and plumb and that the side jamb material will accept fastening screws solidly. If not, repair as needed.
Older window designs vary considerably so these steps should be considered a guideline for the installer with the intent of creating an opening that will allow the replacement window
frame to be installed as shown from the inside against the exterior stops of the old window.