Abstract: A sub-floor tile is provided for use in a modular sub-floor tile system. The sub-floor tile has an upper surface and a lower surface made from one prefabricated, durable, water resistant, mould and mildew growth resistant thermoplastic elastomer with acoustic deadening properties. The lower surface has a series of projections extending away from the sub-floor tile and located adjacent to an underlying surface, such as concrete, when the sub-floor tile is in use. The projections create a space between the sub-floor tile and underlying surface creating a moisture barrier and increased air flow that also permits moisture drainage. This also permits a thermal break between the underlying surface and the overlying flooring surface, such as carpet, laminate, or vinyl.