On Architecture

7. All this, however, I have not set forth for the purpose of changing the usual terminology or language, but I have thought that it should be explained so that it may be known to scholars. I have now explained the usual ways of planning houses both in the Italian fashion and according to the practices of the Greeks, and have described, with regard to their symmetry, the proportions of the different classes. Having, therefore, already written of their beauty and propriety, I shall next explain, with reference to durability, how they may be built to last to a great age without defects.

1. HOUSES 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.

2. It will also do no harm to insert posts between lintels and sills where there are piers or antae; for where the lintels and beams have received the load of the walls, they may sag in the middle, and gradually undermine and destroy the walls. But

3. We must also manage to discharge the load of the walls by means of archings composed of voussoirs with joints radiating to the centre. For when arches with voussoirs are sprung from the ends of beams, or from the bearings of lintels, in the first place they will discharge the load and the wood will not sag; secondly, if in course of time the wood becomes at all defective, it can easily be replaced without the construction of shoring.