Abstract: A modular panel, which in use is laid in a continuous two-dimensional array over a supporting sub-surface to form a hollow floor, wall or ceiling suitable for reticulating electrical, optic-fibre, hydraulic and other conduit. The panel having upper and lower duct zones each partitioned by lateral ribs and longitudinal ribs respectively. The upper duct zone being in communication with the lower duct zone by way of vertical duct sets.