Abstract: A composite gambrel roof truss assembly comprises a prefabricated top truss having a rigid lower chord and two top chords, all connected together to form a rigid triangular top truss unit, with two prefabricated side truss units, each having a rigid diagonal base chord and two outer top chords, all connected together to form a rigid triangular side truss unit whose topmost top chord is dimensioned to be juxtaposed in abutting mating relationship with a corresponding top chord of the top truss unit, and with connector means joining the topmost chord of each side truss unit with its abutting mating top chord of the top truss unit whereby the prefabricated top truss unit can be readily connected at a construction site to both of the side truss units to form a sturdy, rigid composite truss assembly capable of rapid installation by being hoisted bodily into position, and having a peak junction and two hip junctions producing an economical four-chord arched gambrel roof truss assembly of light weight with an unusua