Exh. Hood, Welded Duct and MUA Unit. Frank is adding the 16 Ga. sheet metal to Safe off penetration. You can not see the 2" X 2" angle knee braces that support the duct, mua unit and stack to veneer wall with 14" of double brick underlay. The bldg is 90 years old with a new face. We used the epoxy resin with 3/8" threaed rod to support knee braces. Before anyone asks, there is a cleanout at each direct change.