I have a sound wooden window frame with a single pane of glass in it on the ground floor. The dimensions are ~1mx1m for the main window and ~0.5mx1m for the opening light. The rebate is ~18mm deep, for the main window and ~16mm for the light. I would like to replace the two single panes of glass with double glazing units. The problem is that the rebate is currently not wide enough to take double glazing, the thinnnest double glazing unit is ~16mm which would not leave much room for beading/or butyl compound. I think the my options are :
Secondary glazing fitted to the inside of the frame- although i'm a bit concerned about condensation between panes has anyone got experience of this.
Widening the rebate to accomodate double glazing- does anyone know how I would go about widening the rebate quickly and neatly.
Has anyone heard of a stepped double glazed unit which would sit partly on the inside of the frame without the need to extend the rebate ?
Hope someone can point me in the right direction.
Many thanks in advance.