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Masonry Analysis and Building Techniques at Ostia

Building techniques changed distinctively over the centuries during which Ostia flourished and declined.  The following examples of wall facing illustrate some of the major phases of construction at the Ostian synagogue. The changes in techniques that took place were a result of the larger phenomenon of growth or decline in the construction industry throughout the Roman world.  Factors such as efficiency and scale of an imperial building program played a significant role in how and why construction processes changed as they did.

Opus Mixtum A: Reticulate facing made up of small squares (conical in depth) set diagonally in a regular net pattern, with leveling bands of lateral brick (opus latericium, usually from 3-6 courses) at regular intervals. Quoins consist of tufa block. Mixtum A was mainly used from the mid-first through the second century C.E. although some later examples are known, as well.

Example of Opus Mixtum A

Fig. 1.  A large part of the eastern half of the synagogue complex shows Mixtum A construction. This view (shown above) of the northern section of the West wall in room 10 is a well-preserved example. All materials here come from natural tufa mined for building purposes. The use of tufa and the reticulate pattern in general was common in the earliest building phases before the method of firing clay for bricks took hold. Construction in Mixtum A did occur at later dates, which warns us to be cautious about dating based on the type of construction alone.

Opus Mixtum B: Reticulate facing and latericium bands (as in Variant A), but with brickwork (latericium) quoins. The pattern of quoins interlocking with facing is similar to Mixtum A. Mixtum B is sometimes found on interior walls, where the exterior of same wall is faced entirely in opus latericium. 

Example of Opus Mixtum B

Fig. 2.  This view (shown above) of the NE corner of the North wall in building 2 room 4 is a good illustration of the interlocking pattern of reticulate facing with brick framing. Most of the western half of the synagogue complex (including the large rooms 14 and 18 and building 2) was constructed in Mixtum B at its earliest phase.

Opus Latericium A: Regular courses of lateral brick work for the facing of wall continuous through the quoins and corners. Bricks are cut triangularly and vary in size. Opus latericium was used from the mid first century C.E. onward.

Example of Opus Latericium A

Fig. 3.  This close-up shot of the North wall in room 18 of the synagogue shows the regularity of the courses and the variation in brick sizes (see figure 2 for a view of the entire wall). Opus latericium replaced reticulatum construction for reasons of efficiency and strength; baked bricks were easy to work with and had the endurance to support multiple storey buildings. Both of these features became necessary in the first century C.E. when the population and building production increased drastically at Ostia.

Opus Vittatum A: Facing in alternate courses of block and brick in a 1:1 ratio. The blocks are generally well cut and consistent in size. Vittatum A was used from the late third century C.E. into Late Antiquity.

Example of Opus Vittatum A

Fig. 4.  This view (shown above) is of the exterior of the Torah Niche. The lower half of the wall shows original Vittatum A construction, while the upper half is entirely reconstructed. Notice the regularity of the brick and block courses. Vittatum A is the most regular of this type of construction. The other types of Vittatum (B-C) demonstrate a much greater degree of variation in brick and block sizes and shapes, irregular patterns of courses, and even substitute materials for bricks or blocks. These features suggest the reuse of earlier materials (see figure 3) and coincide with the decline of population and building production that occurred toward the end of the third century onward.  Vittatum construction was used mostly for repair and renovations.

Work Consulted

Sear, Frank. 1982.  Roman Architecture.  Cornell University Press.

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UPDATED 8.24.2009