Abstract: A building structure sealed against hydrostatic pressure and a process for constructing a building structure wherein the building structure is fashioned of concrete or stabilized natural substratum. The building structure is in the form of sandwich-like layers which are applied to a base layer with adherence between the respective layers being accomplished by polymerization. At least one layer is applied to the surface of the structure exposed to the hydrostatic pressure and is allowed to at least partially solidify. A web is impregnated with a synthetic sealing and impregnating compound and applied, in an unpolymerized condition, to the first layer so as to allow the web to polymerize in situ.