Have a shower stall drain that leaked on my HVAC main trunk duct. Rusted a 6in hole in the top of the duct as well as the bottom. There is also a little damage to one the side of the duct and a 4in round branch line leaving the top of the duct in the vacinity of the damage. The duct is 8in X 14in rectangle and is located above finished ceiling. What are the repair options? Would peferably DIY suggestions. Local home improvement store has prefab sections of 8X14 duct in 4ft lengths. Can one cut a 2ft section out of one of these and fit it over the existing duct at the location of the damage, fasten with rivets or self tapping screws and seal the seems with tape? Thanks for any suggestions.