As the manufacturer of the Ole Hickory Pits smokers, the recommended materials for constructing the 4″ or 6″ flue pipe, as well as the 10″ diameter smoke evacuator and should comply with local building and fire safety codes, and at the minimum should be made of 16-gauge steel, single wall, with fire wrap insulation applied where this passes through a combustible ceiling.
The 4″ or 6″ flue pipe should be installed as straight vertically as possible, with any offsets not to exceed 45 degrees. Any offsets should be avoided as they will increase the frequency that the flue needs to be cleaned from at least every six months to every three months. The height of the flue pipe should be at least 4′ above the roof line and anything within a 10′ radius, with a rain cap that flows freely out the sides.