The recent mega-tsunami event on the 26th December 2004, revealed the importance and the necessity of designing “tsunami-resisting” structures. The present study paves a path towards the organization of “design codes” and engineering practices addressing this important issue. A computational model consisting of the nonlinear shallow water equations in the 2DH space, in the presence of an embedded typical building is synthesized and numerically solved by an explicit second order finite difference scheme on a solution domain discretized by a staggered Arakawa “C” grid. The normalized integral of the hydrodynamic loads distributed on the building surface in the direction of the wave propagation is plotted against the normalized length of the structure for various building walls configurations. The importance of the building orientation with respect to the wave propagation and the importance of the openings in the walls are revealed by means of a number of numerical experiments. An experimental verification is pending. The presented numerical tool, in conjunction with the structural resistance analysis of the building walls, leads to operational results as far as the building design specifications are concerned, and mainly in order to resist the expected “design tsunami” and to operate as an “ad hoc” shelter for the people in the vicinity.