How is replacing windows different from putting windows in when the house was built new?
Your house now has finished siding, walls, and trim which you probably want left intact after the windows are replaced to minimize disruption and cost. A replacement window is made to fit into your old window’s sash opening (the area of glass including its frame and any hardware) and doesn’t require the removal of interior or exterior casings. The installation of a new construction window (most likely what is being replaced) would require removal of the entire window including its jamb, head, sill, and casings to expose the stud opening. Although certainly an option, this method is more labor intensive and invasive and would involve walls and siding beyond the casings.
