‹‹‹ Vitr. 2.8.17 | Table of Contents | Vitr. 2.8.19 ›››
18Having explained why, on account of the narrowness of the streets in Rome, walls of brick are not allowed in the city, I shall now give instructions for their use out of the city when required, to the end that they may be durable. On the top of a wall immediately under the roof, there should be a course of burnt bricks, about one foot and a half in height, and projecting over the walls like the corona of a cornice; thus the injury to be guarded against in such a wall, will be prevented; for if any tiles should be accidentally broken or dislodged by the wind, so as to afford a passage for the rain, the burnt brick, a protection to it, will secure the wall itself from damage, and the projection will cause the dropping of the water to fall beyond the face of the wall and thus preserve it.
18It has now been explained how limitations of building space necessarily forbid the employment of brick walls within the city. When it becomes necessary to use them outside the city, they should be constructed as follows in order to be perfect and durable. On the top of the wall lay a structure of burnt brick, about a foot and a half in height, under the tiles and projecting like a coping. Thus the defects usual in these walls can be avoided. For when the tiles on the roof are broken or thrown down by the wind so that rain-water can leak through, this burnt brick coating will prevent the crude brick from being damaged, and the cornice-like projection will throw off the drops beyond the vertical face, and thus the walls, though of crude brick structure, will be preserved intact.