By Kevin Murphy
KANSAS CITY, Mo (Reuters) - Now, here's a second home to stretch out in. A Virginia man is building a 72,000 square-foot house in the Missouri Ozarks with 13 bedrooms, 14 bathrooms and other features that could include a library, music room, theater and a garage measuring 4,000 square feet.
With a footprint equivalent to a little under two acres, it would be one of the country's largest privately owned houses, according to various lists.
But it's the materials that homeowner Steven Huff seems most proud of when he talks about the castle-like structure on 500 wooded acres in southwest Missouri.
The house is made from a special steel-reinforced concrete that is energy-efficient and resistant to various forces of nature -- notably tornadoes in an area prone to them.
Huff, 60, is chairman of TF Concrete Forming Systems, which makes the concrete. He grew up in Missouri.
His mansion-in-the-making, called Pensmore, has drawn so much attention and speculation that he released a prepared statement this week about it.
"The mission behind Pensmore is to serve as a living laboratory for ongoing research into energy conservation and disaster resistance," he said.
"While the structure will also be a home to my family, our hope is that curiosity and gossip will fade to make room for the valuable insights a project of this scale can yield for building the homes, schools, hospitals and office buildings of the future."
The idea is for the structure to be big enough to serve as a model of efficiency and durability for large commercial buildings, even though it is a house, said Luke Pinkerton, founder of Helix, which is providing steel for the project.
The concrete is mixed with bits of steel, poured into wall forms and insulated on the outside, Pinkerton said, and concrete absorbs the heat, keeping the house cooler.
There are already many buildings using the material, but Pensmore will be a high-profile example, he said.
"The concept is very relevant in our times," Pinkerton said. "Energy costs are getting higher."
A portion of the house can be seen by motorists on U.S. Highway 65 between Springfield and Branson, Mo.
The house is probably more than a year from completion, said Todd Wiesehan, planning and zoning administrator for Christian County. It will use nearly $6.9 million in building materials, according to the permit application, he said.
Huff plans to give tours of the house to the media and others in mid-August, said Eva Van Brunt, his spokeswoman.
"It's hard to fathom 72,000 square feet," said Lou Lapaglia, presiding county commissioner. "I'm interested in seeing in its totality."
Huff and his family will live in the house for part of the year, Van Brunt said. He has four children, Van Brunt said.
"We are glad they are investing in Christian County," Lapaglia said. Property taxes the house generates will go mostly to the public schools, he said.
Matt Meadows, a real estate agent for a nearby residential development, said he doesn't consider the house outlandish or unnecessarily large.
"Not if someone has the money and has the land, that's why it's America," Meadows said. "I wish I could build something like that."
(Editing by Tim Gaynor and Ellen Wulfhorst)