A ram air fan outer housing for directing air from a ram air fan rotor and air from a ram air bypass into a ram air fan outlet. The outer housing includes an outer cylinder and a plenum connected at a joint region. The outer cylinder is made of a laminate stacking sequence of at least four adjacent layers of plain-weave carbon-fiber fabric in an A-B-B-A sequence. The plenum is made of a laminate stacking sequence of at least eight adjacent plenum layers of plain-weave carbon-fiber fabric in an A-B-B-A-A-B-B-A sequence. The plenum is joined to the outer cylinder at a joint region, the joint region includes a transition section transitioning the laminate stacking sequence from the eight adjacent layers of the plenum walls to the four adjacent layers of the outer cylinder walls.