Tsunamis, dam-break waves and impulse waves are catastrophic phenomena that leave thousands of victims and cause severe infrastructural damage. Understanding the impact that these waves have on structures is therefore necessary to properly dimension buildings in wave hazard zones. Previous studies have analyzed the impact of waves on structures, and the effects of building orientation and porosity have been separately investigated, however both factors have not been considered simultaneously. In addition many discrepancies are found in the literature regarding expressions to calculate wave-induced forces. In this study, waves are generated in a laboratory environment, and their impact on buildings with openings is analyzed for different orientations. Results show that rotating the structure does not have an effect on the recorded forces per unit with, but rather delays the time at which forces peak. At the first stages of the wave impact, the influence of streamlining appears to be more important than that of the porosity, and this behavior is then inverted. An expression to predict force maxima is given, with excellent agreement for tsunami-like waves, and conservative estimates for more impulsive waves.