Abstract: An adjustable roof jack adapted for mounting on a flat or pitched roof. The roof jack is connected to a lower end of an air discharge duct from an air conditioning unit and to the top of an air supply duct in the roof. The roof jack includes an angular-shaped sheet metal lower frame member having a front side, back side, a first side and second side. A lower portion of the sides of the lower frame member is received around the top of the air supply duct. Also, the lower portion of the sides of the lower frame member is integrally formed into to an outwardly extending roof flange. The roof jack also includes an angular-shaped sheet metal upper frame member having a front side, a back side, a first side and second side. A top portion of the front side of the upper frame member is hinged to a bottom portion of the front side of the upper frame member.