An inflatable mold assembly for forming a hollow composite construction member that is suitable for use as a building material has a longitudinal axis. The mold assembly further has a flexible, substantially tubular bladder wall defining an elongated inflatable cavity. A reinforcing fabric is positioned concentrically around the flexible bladder wall. A flexible air-impervious outer layer is positioned concentrically around the fabric, with the bladder wall and the outer layer defining an elongated annular space, and with the fabric being positioned within the elongated annular space.