A modular enclosure, such as a shed, may include a floor constructed from one or more floor panels. The floor panels, which may be constructed from blow-molded plastic, may include a pattern disposed on the upper surface. The floor panels may also include depressions that are formed in the lower surface and extend towards the upper surface. If desired, the depressions may be generally aligned with a portion of the pattern in the upper surface and the depressions may have a length that is less than the distance separating the upper surface and the lower surface. Advantageously, the depressions may be sized and configured to increase the strength of the floor panels. In addition, the floor panels may include a pattern disposed on the lower surface and the depressions may be at least partially disposed in the pattern. The patterns on the opposing sides of the panels may be generally offset and/or have different orientations.