The plant module comprises a base deck, a frame and a plurality of pieces of equipment mounted to the base deck and/or the frame; the base deck comprises of a grid of base beams; some of or all the beams of the base deck and optionally some of or all the beams of the frame are perforated, in particular castellated-type or cellular-type, so that they have a plurality of holes, in particular web-openings, for receiving conduits and/or pipes and/or trays.