At first, the couple had their reservations about the home's unconventional design. 'We weren't so sure about how we felt about an underground house,' Ms. Gilbar Treadwell said. For a time they thought they might even add a second story to the home. But after the first year of living in the home, she said they loved the feeling of it. Over the years they've roughly doubled the size of the home, from approximately 2,000 square feet to 4,100 square feet.

'Not many people can say they mow their roofs,' Mr. Treadwell said. He says he trims the roof, shown here, once a year. The soil above the roof provides insulation throughout the year. From the rear of the property, the home seems to disappear into the hillside. It has 'a total feeling of solidity,' he said.

The property sits on 30 acres with expansive views of mountains and hiking trails. In the winter, ski trails are visible from the living room. The couple's renovation ensured that the home is filled with light throughout the day, with windows on both the east and west sides. 'The great thing about this house is we get both sunsets and sunrises,' Ms. Gilbar Treadwell said.

The couple describe the home's style as a mix between a Frank Lloyd Wright home and a Craftsman. The wooden ceiling beams are original to the home and the flooring features radiant heating. During their renovation, the couple gutted the space and took down some interior walls for a more spacious layout. The double-sided fireplace, with a green tile surround, is shown at center.

The other side of the fireplace opens to the dining-room area. To keep the integrity of the original wood ceiling beams, the couple used a string lighting fixture that uses low-voltage halogen lights. Mr. Treadwell says they've invested upward of $1.3 million into the home. The renovation would have cost more if not for Mr. Treadwell serving as general contractor, he said.

All the interior doors, south-facing windows and some woodwork in the home are from oak wood salvaged from a former church in Lowell, Mass., Mr. Treadwell said.

Both owners are photographers by trade and are now semiretired. Mr. Treadwell also has some commercial real-estate interests in Santa Barbara, Calif. They're looking to sell because they're spending more time at a cottage on the coast of Maine and live in California during the winter. They expect to retain a presence in the area after the sale. One of the bedrooms is shown.

The home has two bedrooms and 2½ bathrooms, with space for a third bedroom. The master bathroom, shown here, includes some of the salvaged wood from the same church in Lowell, Mass. The trim around the walls was part of the choir loft, and a shelf on the wall was once used to hold the communion chalice. 'We refer to it as the shampoo shrine,' he said.

The kitchen area is shown.

The property also includes a garage space and a studio, where Ms. Gilbar Treadwell would make hats. The studio, located on the eastern end of the house, is shown.

The home was listed in 2012 for $1.9 million before being reduced to its current price of $1.575 million. It was relisted in June with Martha Diebold of Martha E. Diebold Real Estate