I am having an old UPVC conservatory pulled down. Elsewhere I have an open sided lean to shelter attached to the house which currently is roofed with thin polycarbonate sheets that are failing and need to be replaced. The timber supports for the lean to roof are very strong and sound. Could the UPVC double glazing units be used to create a clear glass roof as single sheet glass? as a double glazed unit? or not at all? If this is possible how can I make it work well & be safe?