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Ralph L. Patty - Reviving Rammed Earth
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Extension engineer Ralph Patty

All images courtesy: South Dakota Agricultural Heritage Museum, Brookings

Ralph Patty took an ancient construction method and studied its science for the benefit the farmers of South Dakota. This in turn impacted rammed earth architecture worldwide. He laid the groundwork for rammed earth construction to be a viable part of the modern sustainable architecture movement 30 years after his death.


Between 1909 and 1916, Patty worked as a public school teacher and principal of the Brookings High School. The South Dakota Extension Service hired him in 1916 as the first South Dakota Extension Service Agricultural Engineer. At SDSU he taught Structures, Soil and Water, and rural electrification. His most important research involved constructing buildings using rammed earth. He also conducted research on the development of rural electrification, non-rammed earth farm structures, and research on various types of mechanical farm equipment. In 1924, he became head of the Agricultural Engineering Department, holding this position until his death in 1945.

Starting in the 1920s, Patty conducted research on rammed earth construction at SDSU to improve poultry barns. High humidity within poultry barns caused the birds to die from pneumonia in the winter. Patty built a wood barn, a concrete barn, and a rammed earth barn. The only turkeys that survived that winter were the turkeys in the rammed earth building. The construction method allowed the moisture to escape while maintaining a constant temperature.

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Rammed Earth Poultry House. This is one of the rammed earth buildings Ralph Patty promoted for housing turkeys.

Patty saw the benefits for this ancient building technique since farmers in the remote areas of South Dakota could harvest the building materials from their own land. It was more labor intensive than the conventional construction methods but it had more benefits.

He built test walls to see which soil combinations, construction methods, and surface treatments would work the best. Dr. Henry DeLong, who began as a graduate student under Patty, continued the research on rammed earth after Patty died. Patty and DeLong collaborated with researchers in Australia and Africa. Their research laid the foundation for modern rammed earth construction worldwide.


Ralph L. Patty was the youngest of four children born to David J. and Elmina Hastings Patty. He was born August 28, 1884, in Redfield, Iowa. Ralph’s father was an implement dealer in their community. Ralph attended Iowa State Normal School, graduating in 1907. He earned his Bachelor of Agricultural Engineering at Iowa State College in 1909.

August 10, 1909, Ralph married Gertrude P. Jones at Ames, Iowa. Their children are Gertrude E. and Leland J.

Ralph enjoyed sports. He played football and baseball for Iowa Teacher’s College. At SDSU, he was a member of the faculty athletic committee and the coach of the tennis squad. Ralph loved the game of golf and designed the first clubhouse at the Brookings Country Club on Lake Campbell. Ralph died at age 61, November 6, 1945.

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Ralph Leland Patty ca. 1925. Born in 1884 in Iowa and died in 1945 in Brookings, South Dakota.

What is rammed earth construction?

Pisé de terre (rammed earth) construction compacts earth into a form to build a structure. Unlike adobe (mud brick), rammed earth walls are made with very little moisture (6-12 percent) and do not require drying to harden. For these reasons, rammed earth buildings can be made in humid climates. Rammed earth walls use a combination of sand and silt with a little clay and some cement.

How do you build a rammed earth building?

It starts out with a solid foundation such as a concrete slab. Similar to building a concrete wall, forms are set up. The slightly damp soil mixture is placed into the forms in small layers. Each layer is compacted with a tamping tool by hand or by machine. The forms are removed immediately after the last layer is rammed. Once the walls are built they are sealed. Today builders spray the walls with a clear matrix that seals the walls but allows it to “breath” moisture out.

What are the benefits?

Rammed earth is a sustainable building material. Made from local materials, it requires only a small percentage of cement to build a strong structure. The walls are more thermodynamic than concrete block. Heat transfers more slowly through rammed earth than concrete block so it is cool in the summer and warm in the winter. It also conducts moisture so there is less interior humidity. With a solid foundation and a good roof, a rammed earth building will last for thousands of years.

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Rammed Earth Building in South Dakota.1933-1940. The exact location of this building is unknown.

Land grant colleges began organizing Agricultural Engineering departments in the 1920s. They developed in response to the rapidly changing farm environment. Farming became heavily mechanized and much more technical. Mechanized farm building ventilation, grain storage and movement, irrigation, and livestock waste disposal were quickly changing farm operations. The mechanization did not end at the barn. Farm homes were acquiring new sewage and water handling systems, lighting and improved heating methods. Ralph Patty spent his career finding better solutions for farm buildings and structures.