‹‹‹ Vitr. 6.7.7 | Table of Contents | Vitr. 6.8.2 ›››
8In those buildings which are raised from the level of the ground, if the foundations are laid according to the rules given in the preceding books for the construction of walls and theatres, they will be very durable; but if under-ground apartments (hypogea) and vaults are to be built, their foundations must be thicker than the walls of the upper part of the edifice, which, as well as the pilasters and columns, must stand vertically over the middle of the foundations below, so that they may be on the solid part. For if the weight of the walls or the columns have a false bearing, they cannot last long.
8Houses which are set level with the ground will no doubt last to a great age, if their foundations are laid in the manner which we have explained in the earlier books, with regard to city walls and theatres. But if underground rooms and vaults are intended, their foundations ought to be thicker than the walls which are to be constructed in the upper part of the house, and the walls, piers, and columns of the latter should be set perpendicularly over the middle of the foundation walls below, so that they may have solid bearing; for if the load of the walls or columns rests on the middle of spans, they can have no permanent durability.