Your window may be defective if there is a gap between the window pane and the frame. They may have manufactured it incorrectly.
If the gap is between the beading and the pane of glass, and the pane is able to move in the frame, this may be an easy fix. The beading may have shifted and you can push it back in. Check to see if it has lifted away from the edge of the frame.
Using the wrong beading could cause the gap. In this case, we would need to replace the beading with the correct material. If you have a double glazed window, it might not be tightly enclosed. This can happen if it has the wrong size triple glazing beading, for example.
If either of these scenarios occur, and you purchased your windows from us, please call us or request a service visit.