Rubble trench foundation

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The rubble trench foundation, a construction approach popularized by architect Frank Lloyd Wright, is a type of foundation that uses loose stone or rubble to minimize the use of concrete and improve drainage. It is considered more environmentally friendly than other types of foundation because cement manufacturing requires the use of enormous amounts of energy. However, some soil environments are not suitable for this kind of foundation; particularly expansive and porous soils.

To construct a rubble trench foundation a trench is dug down below the frost line and then filled with drainage tile and loose stone. A concrete cap is poured to provide ground clearance.

These kinds of foundations are also sometimes called rubble stone foundations. They are sometimes constructed with mortar and fairly large stones. Although perhaps more environmentally friendly, rubble stone foundations are often significantly inferior from structural and load bearing standpoints, particularly those constructed in the late 19th, and early 20th centuries. Prior to modern-day mortar use, they generally were constructed using simple sand, limestone, and water based mortars. These kinds of joints do not weather well, and foundations of this type fail regularly. These failures can lead to significant reconstruction and repair challenges. Not only are they costly, but they are true physics and problem solving challenges.