Will soon be installing quad mt vernon. My dealer ordered me a 12 inch horizontal pipe which will go thru the wall and then connect to a 5 ft vertical on ext wall. Have not started install yet but the wall is a solid 12 inches alone and i believe i need to be 6 inches from ext wall for the vertical piece. What are my options here. Using duravent with orange seal. Was at lowes lookin for extension pieces and they had duravent with rope. Not sure if compatible. Also do i need to be sealing, screwing together pipe? Thanks this wil be first stove.