Hello friend... Just fabricated a chimney cap to install over two of my fireplace flues... The top roof was made of sheet metal, and I want to install copper over this metal... What would be a good adhesive that would withstand the heat, and not have a bad effect on the copper... Some high temp. RTV silicone caulkings have a bad reation with copper... thanks A lot... :)

Installing copper on top of sheet metal is not a good idea for this application. The two metals have different coefficients of expansion and will warp when heated.