Modular Architecture Q&A: Transportation Costs

Below is the second post in the continuing series of prefab/modular Q&A asked by Norman Gray, a graduate student at the New School of Architecture and Design in San Diego, CA and answered by James B. Guthrie, AIA, President of Miletus Group, Inc.

Question:
Is transportation of prefab/modular units a significant cost factor?

Answer:
The general answer would be ‘yes’, but how significant is dependent on the details of the project. These details include: the distance and travel conditions between the project and the factory, the size and weight of the prefab components, and the cost of labor at the two locations. To illustrate the extremes, I am aware of projects that were as simple as lightweight bathrooms pods built less than a mile from the project site, to very heavy fully furnished apartment modules that were shipped hundreds of miles, over both seas and roads, and even between two countries. The cost of the transportation was clearly very different being much greater in the second example, yet both projects made financial sense.

To understand the impacts of transportation, keep in mind that costs associated with transportation are not new or exclusive to prefab vs site built. All building construction has transportation costs inherent in the project. Regardless of the method of construction, both materials and labor come from somewhere other than the construction site.

To understand the differences, however, let’s first consider the case of the transportation of labor. In this regard, offsite construction is particularly efficient vs onsite. Workers at a factory tend to live near the factory and so have very consistent and minimal travel distances to the work site (ie the factory). Additionally, carpooling and other energy efficient commuting options become very real in this scheme. In the case of onsite construction, the travel distance for labor is a variable and completely dependent on the location of the trades needed and the building being constructed. Onsite construction requires a more skilled labor force than offsite construction. It is often the case the specialty trades will travel greater distances to reach a construction site than unskilled labor to factories. For onsite construction the location of the worker to the work site is in constant flux with each building built. This is not so with offsite methods.

There is a similar effect with the delivery of materials. Offsite construction occurs on singular factory sites where there tends to be large and protected staging areas. This means materials can be ordered and stored in weather protected areas in bulk far in advance of assembly. Factories also tend to be geographically clustered and located within proximities to construction material suppliers. These two factors greatly increase the efficiency of material delivery to the point of assembly.

For prefab, there is then unique cost of transporting large assemblies to the building site. Unlike traditional onsite labor and material logistics, however, prefab assemblies carry with them substantial embodied bulk material and embodied bulk labor, and are thus extremely efficient transportation hauls.

Because of these efficiencies and the addition of labor to the total transportation cost of building, the equation of transportation related costs and its percentage of the total building cost, has many components and modifiers to consider in the final equation. This is why, depending on the project, it can actually be cost effective to ship large and heavy modules long distances.

Related link: http://www.newschoolarch.edu

© Miletus Group, Inc. 2011