Pensmore is a manor under construction in the Ozark Mountains of Highlandville, Missouri. When completed, the home will be the private residence of Steven T. Huff and his family. It will be one of the largest private single-family residences in the United States. Huff is the chairman of TF Concrete Forming Systems, which is doing the concrete construction work for the home. Huff at one time worked in Army intelligence and was a CIA officer.[2]Huff later founded Sensor Systems in 1993 and served as its CEO. The company, later known as Overwatch Systems, created leading commercial software products for medical, defense and intelligence applications


Steven T. Huff Family LLC applied for a construction permit in 2008 to begin construction of the mansion. The home is unique, as it is an insulated concrete form structure that is designed to showcase sustainable construction techniques on a large scale. The home is designed to be earthquake resistant, bullet proof, blast proof, tornado resistant, bug resistant, and fire resistant. The home is capable of withstanding an EF5 tornado.[5]

The home will approach net zero on heating and cooling. Pensmore will utilize thermal heat collectors, a geothermal ground source heat exchanger, radiant heating and cooling, advanced climate control software, rainwater collection, and helix steel fibers.[6]

Huff told the New York Times that he built the House “to demonstrate the viability of new concrete technology that he believes will lower energy consumption.”[7] The home’s large size and its location in the Ozarks (which experiences both high and low temperatures, as well as tornadoes) were chosen so that Huff could explore how the concept works on a commercial scale and under a broad range of climate conditions.[7] The home is also being built in an area where it is not subject to government building inspections or regulations.[7]

On July 3, 2016, the Associated Press reported that lawyers for Stephen T. Huff, Pensmore’s owner, filed a lawsuit against Monarch Cement Company, of Humboldt, Kansas, and its Springfield subsidiary, City Wide Construction Products, seeking $63 million in damages. The suit claims the mansion was shorted more than 70,000 pounds of a crucial steel fiber, named Helix. Invented in a laboratory at the University of Michigan, Helix is an alternative to rebar and was developed for the U.S. Army Corps of Engineers, the lawsuit said.