To replace a casement window sash, unmount the existing sash by removing the hinge screws or sliding the sash out through the sash channel. Existing hardware is replaced or transferred to the new sash before mounting and installation. Slide the sash onto the hinge arms before screwing it into place.
Before replacing an existing sash, remove all window coverings and exterior screens. Use a utility knife to ensure the trim does not peel before removing the stops with a putty bar or similar device. Remove all visible nails and hardware before removing the existing window. Clean the frame thoroughly after removing the existing sash and balance to ensure smooth installation and proper mounting of the replacement. Older windows may have sash weights which are cut and removed before filling the weight compartments with insulation.
After preparing and cleaning the opening, install the metal clips needed to keep the balance in place. The balance is then installed. Install the top sash using the sliders before leveling the window and lifting it into place. Use adjustment screws to ensure proper positioning of the sash before adding the trim and filling any air gaps or holes with insulation or expanding foam. Recess all nail heads before filling the holes with wood putty and painting the new sash.