‹‹‹ Vitr. 5.10.2 | Table of Contents | Vitr. 5.10.4 ›››
3The ceilings, if of masonry, will be preferable; if, however, they are of timber, they should be plastered on the under side, which must be done as follows. Iron rods, or arcs, are prepared and suspended by iron hooks to the floor as close as possible. These rods or arcs are at such distances from each other, that tiles, without knees, may rest on and be borne by every two ranges, and thus the whole vaulting depending on the iron may be perfected. The upper parts of the joints are stopped with clay and hair. The under side towards the pavement is first plastered with pounded tiles and lime, and then finished with stucco or fine plastering. If the vaulting of hot baths is made double it will be better, because the moisture of the steam cannot then affect the timber, but will be condensed between the two arches.
3The vaulted ceilings will be more serviceable if built of masonry; but if they are of framework, they should have tile work on the under side, to be constructed as follows. Let iron bars or arcs be made, and hang them to the framework by means of iron hooks set as close together as possible; and let these bars or arcs be placed at such distances apart that each pair of them may support and carry an unflanged tile. Thus the entire vaulting will be completely supported on iron. These vaults should have the joints on their upper side daubed with clay mixed with hair, and their under side, facing the floor, should first be plastered with pounded tile mixed with lime, and then covered with polished stucco in relief or smooth. Vaults in hot bath rooms will be more serviceable if they are doubled; for then the moisture from the heat will not be able to spoil the timber in the framework, but will merely circulate between the two vaults.