Probably no building technology is as synonymous with the Great Plains as the sod wall. This construction material was mined from the surface strata of Plains soils, complete with the roots and rhizomes of prairie grasses and forbs. The structural strength of the material was derived from the root mass, whose interlocking structure composed significantly more than half of the soil strata.
The area of shortgrass and mixed-grass Great Plains prairies constitutes the principal region of sod-wall construction. While a few examples are known to have been built from true prairie sods in eastern Nebraska, Iowa, and southwestern Minnesota, these are generally exceptional. (Whether this is for historical or environmental reasons has not been determined.) Some true prairie grasses such as big bluestem (Andropogon gerardi) were popular for sod-wall construction in mixed prairie environments where these grasses extended westward along valleys.
The diverse expanse of the Great Plains affords many different habitats for grassland vegetation. Grass communities preferred for sod-wall construction were sod-forming varieties rather than bunchgrasses. Any level or nearly level site with a contiguous stand of a dominant, sod-forming grass provided suitable material, but preferred stands were often found in moist valleys, lowlands, or larger sinks known as buffalo wallows. Under locally advantageous conditions, bunchgrasses such as the adaptive little bluestem (Andropogon scoparious) might even be present in a sodforming habitat.
Buffalo grass (Buchloe dactyloides) was one of the most important grasses of the High Plains of Nebraska, Kansas, and Colorado, where it was often found in pure stands. Its sod is extraordinarily dense, with a structure of fine but very tough and wiry roots spreading widely in all directions. Together with the roots of adjacent plants, buffalo grass forms a dense, multidirectional mat with considerable tensile strength. This root system allowed for the cutting of bricks of great dimensional stability.
Little systematic investigation has been made into the biological composition of sods in actual walls. Existing data come from reminiscences. While many of these suggest that pure stands of certain grasses were used, most of them likely describe the predominant grass in a mixed community. In the Central Plains grasses most commonly used included bluestems, buffalo, prairie cordgrass (Spartina pectinata), and wheat, Indian, and wire grasses.
The antecedents for sod construction on the Plains are still shrouded in mystery. Several studies have speculated on origins, but none has been able to prove its theory. It is unlikely that sod construction originated from immigrant introduction or "pioneer ingenuity" or that it was copied from the membranes of Native American earth lodges. Early observations of the material do not offer reliable evidence or provide clues. Sod walls were often referred to as "dobes" by early observers, and after the proliferation of sod-wall construction, many clay-walled buildings came to be called "soddies."
The earliest reliable account of the use of sods for building comes from Fort Kearny on the Platte River in present-day central Nebraska. There, in 1848 Lt. Daniel P. Woodbury started his troops preparing adobe bricks but later shifted their effort to the cutting of sods in order to speed construction. The technology appears to have diffused from there up and down the Platte River valley and then to near and distant places around the Great Plains. The diffusion, however, was concentrated in the Central Great Plains.
Reminiscences and photographs of sod buildings appeared in the latter part of the nineteenth century, and these, together with numerous extant structures, allow description of a technology that evolved into the twentieth century. Early photographs of older structures suggest that the sod was cut with spades, the sod blocks approximating the size of adobe bricks. Often these blocks depict very crude construction. Eventually, blacksmiths and others designed customized plows not to break the sod but to carefully turn it in order to later cut it into building blocks. These ultimately led to the development of the "grasshopper" plow, which produced large blocks of uniform cut that greatly enhanced the quality of construction. By the 1880s this plow appears to have completely supplanted all older cutting technologies. The great diffusion of sod-wall construction followed the development of this specialized plow, which was manufactured in and distributed widely throughout the Central Plains.
Sod was used to construct a wide variety of house types as well as numerous other buildings, although multiple-story buildings were rare. Plowed bricks–"prairie marble"–were laid in masonry fashion grass side down, the first layer typically on undisturbed soil that had been cleared and leveled. Walls were commonly built two bricks wide with staggered joints and bond courses. Each course was leveled with soil. The use of lumber as a leveling device near midwall became a prominent part of the evolved technology. Roof structures, almost exclusively hipped, used dimensional lumber and wood shingles. Walls constructed for permanent abodes were hard plastered inside and sheathed with a variety of materials outside to prevent erosion. Finished with wood floors and plaster ceilings, interiors were like any other American house of the period except for their greater thermal comfort.
Americans unfamiliar with earthen construction initially experienced great difficulty building good-quality structures. Considerable experimentation was required to perfect the technique, which often seems to have been accomplished by specialized local builders. In other cases, individuals built two or more structures before achieving a size and quality that allowed occupation of the same building for more than a few years.
Like other American uses of native materials, sod was considered a temporary and undesirable method of construction. Most soddies were occupied for only a short period before they were replaced with industrial light-frame constructions. Some others, however, were occupied for decades by owners who overcame the stigma of living in "dirt" houses and who valued the thermal and economic advantages of the sod house. The evolved technology was thoroughly American and became, though fleetingly, a significant regional vernacular.
David Murphy Nebraska State Historical Society
Alberts, Frances Jacobs, ed. Sod House Memories. Hastings NE: Sod House Society, 1972.
Weaver, J. E., and F. W. Albertson. Grasslands of the Great Plains: Their Nature and Use. Lincoln NE: Johnsen Publishing Company, 1956.
Welsch, Roger L. Sod Walls: The Story of the Nebraska Sod House. Broken Bow NE: Purcells, 1968.