Building Materials and Techniques

Much of the ensuing discussion will focus on the working-out of structural sequences, first within individual houses or parts of houses, then within the insula as a whole. As a preface to this discussion, it is necessary to give a description of the building materials and techniques found in the insula. Brief surveys of Pompeian building techniques have appeared in various publications. Still one of the most serviceable accounts is that of R. C. Carrington in his article ‘Notes on the building materials of Pompeii” published in 1933, and most of the forms of construction found in I10 are discussed therein. First, the materials. The commonest is the socalled ‘Sarno stone’ (often inaccurately called limestone’), a yellowish white calcareous tufa which is very rough and porous, being riddled with the imprints of shells and vegetable matter; it is used both in large blocks to form quoins and the like and in smaller rubble for facing and infilling of all types. Next most common is a hard grey (trachytic) lava which is stronger and more water resistant than Sarno stone but which, because it is less easy to cut into regular shapes, is generally employed in the form of small rubble. An exception to this rule is its use for door thresholds, where its hardness is well suited to withstanding wear and tear. Rather less common in our insula is the red or purple vesicular lava known as cruma (English “scoria”), derived from the frothy upper crust of consolidated lava streams; it is occasionally cut into small blocks but more normally occurs as a sporadic material in rubble wall-facings where Sarno stone and grey lava predominate. The other main lithic materials found in the insula are varieties of tufo (tuff), formed by the consolidation of volcanic ashes. The brown or grey tuff from Nuceria (modern Nocera) is a hard and close-grained material containing darker brown or blackish specks. It can be easily cut to shape when freshly exposed in the quarry but hardens later on contact with the air, so is ideally suited for producing ashlar blocks, small tufelli (blocks of similar size to modern house bricks) and the pyramidal pieces used in reticulate work (opus reticulaium: see below), not to mention carved detail such as column and pilaster capitals.