Brick and Mortar: Exploring the economics of building techniques at Rome and Ostia

The economics of building structures in the Roman Empire is important as it creates a greater understanding of both the structures left behind and the society which constructed these structures. One of the key building blocks of Roman construction was the so called Roman concrete which was a mortar made of volcanic sand and high quality, was a critical part of building in both and Ostia. For this particular subject the focus was on a hypothesis proposed which stated Roman concrete was more economical than ashlar. To attempt to test such a hypothesis required a series of assumptions and the Diocletian’s Price Edict. To further work with this hypothesis three quantitative exercise were established to help answer the question. First, the factors involved in building on cubic meter of concrete wall. Second, exploration of economics of two styles of brickwork building. Third, the relative cost of ashlar and concrete. With these three things established it created the opportunity to examine economics and issues.

One of the important issues which this article covered was the problem assigning value. The Diocletian’s Price Edict was one of the few documents from the Roman time period which concerns price. But, this document was from a specific period which makes it difficult to use for the centuries of Roman rule. Furthermore, early 18^th century building technique information must be used to help understand the labor costs. This difficulty in establishing price was important because the assumptions made must be useful enough to create a larger economic model which allows an actual examination of the labor costs of building concrete.

With the labor for brickwork, it was fairly dependent on the quality of brickwork. Higher quality brickwork resulted in more expensive labor costs as the process was slower and only so many bricks could be laid per day. Thus a number of structures including the Baths of Caracalla which we visited were examined to understand the amount of brickwork required to build such a structure. A formula exists which can be used to calculate the time in hours per cubic meter of brick laid down. What this information ultimately led to the conclusion regarding brickwork and labor for concrete. The conclusions were first it provided employment to the urban poor and the larger structures were a public good which could be consumed by the citizens of the empire.

The impact of materials supply and production for concrete construction was examined as well. A number of assumptions are made regarding this in order to be able to generalize this information further. The section examined the supply issues for construction of buildings depending on the material composition and location relative to sources of material. This information is used to generate charts which show the relative labor costs for different types of building construction given skilled and unskilled labor. Transportation costs are also given which creates a total which has a high estimate and a low estimate.

The cost of ashlar is also examined relative to the cost of concrete. It was first determined savings in labor costs can be made in recycling building material. Thus labor costs are significantly higher for building using ashlar and concrete is a cheaper substitute, as ashlar is still labor intensive even when recycled. This helps conclude the piece, the author’s hypothesis was found to be valid and concrete is a substitute for ashlar. There is an acknowledgment of the potential weaknesses of some of the various assumptions made throughout the work. But, for the most part these are found to be true by the author and thus the information allows an understanding of the economics of Roman construction.

This information ties in closely with what I observed in both the Baths of Caracalla and other ancient Roman ruins. It was clear to see the style of brick work and the relative costs which would be associated with each type. It was fascinating to be able to see the work of an ancient empire in this way and see the economics which existed behind the both public and private buildings.

The Baths of Caracalla in Rome