16. Most windows are “clamped” in place with stop molding on each side of the wall. Use hammers, putty knives and pry bars to dislodge the old stop molding. Exterior stops can be removed to install the window from the outside. For indoor installations, remove the interior stops. With the stops gone, carefully push the old windows out of the frame.
17. Remove and replace any rotted wood in the window’s sill plate or framing prior to installation.
18. Refer to the window manufacturer’s instructions for specifics on assembly, which may include accessory pieces, such as vinyl sill extenders to help fit the window into the opening.
19. If installing the window on a sloped sill, use wood blocks along the sill to help level and support the unit from below.
20. Make sure the replacement window fits into the opening level, plumb and square, otherwise it won’t open/close properly. Check both sides for plumb.