Although not built in a factory and trucked to the site, rammed earth and the new rammed earth Watershed Block from Watershed Materials have the potential to capture many of the same benefits as prefab - affordability, shortened construction time, reduced materials, and less waste. How so you ask? By going modular.

The new prefab (think haute shipping containers) combines the speed and efficiency of building structural elements on an assembly line with an architect’s cleverness at coupling those structural elements into a group of exciting spaces. Lake|Flato’s Porch Houses are fully assembled units, trucked to the site, sometimes coupled together into larger modules, and placed in such a way as to create additional living spaces, most often outdoor spaces. Blu Homes builds frames with hinged walls trucked to the site and “unfolded” into living spaces. Multiple frames create additional rooms.

What these and dozens of other prefab housing companies have in common is modularity. Modularity is the degree to which a system's components may be separated and recombined. Rammed earth walls can leverage modularity by re-using a forming system to build repeating volumes that are placed in such a way as to create additional living spaces between volumes. Watershed Blocks can leverage modularity by capturing the same value of repeating volumes, and doing so with an assembly of small modular units designed carefully as to require no cutting of blocks and no waste.

The principle is simple: build two boxes, space them a dozen or more feet apart, and drop roofs onto and between the boxes - two boxes, three spaces. Build three boxes and a remote support and drop on roofs - three boxes six spaces. The architect’s cleverness keeps the boxes from being boring.