Timber joinery profiles can be too narrow to accommodate IGU and the process of preparing the frame to take IGU leaves the only a thin strip of timber either side of the IGU to hold it in place. Often there are gaps around sash frames which cause draughts so whilst you might be reducing the heat loss through the glass, you cant avoid the cool area coming into the home night and day.

uPVC Frames can be inserted into the outer perimeter frame of the wooden window once the internal timber and glass components are removed. The look of uPVC i