Su-z Allen and her husband, David, were driving across Texas when they saw an unusual sight along the highway, a cluster of domes. Intrigued, they pulled off the highway and took an impromptu tour of the buildings, dome homes built by the Texas company Monolithic Domes. The couple was hooked. They knew they had to have one.

That was 1991. This year, they finally started construction on their dream home, a thin-shelled concrete dome house near the intersection of Carey Avenue and Lamb Boulevard.

In part, it was the uniqueness of the homes that attracted them. But in large part, they were attracted by the energy efficiency of a dome and its durability.

"They're fire proof, earthquake proof, tornado proof, hurricane proof ... virtually indestructible," Su-z Allen said.

"The concrete acts as a passive solar heat sink. It radiates the heat more evenly than a traditional home," said contractor Ray Ansel, who has built more than 200 Monolithic Domes. "The heat goes right up the wall and across the top in what they call a fly wheel effect. There's never more than a few degrees difference across the dome."

Su-z Allen originally spoke with Ansel about putting a dome around her existing one-story house. Those plans were scrapped when a fire destroyed the house that very afternoon. The couple was only able to salvage the cellar, a rare amenity in Las Vegas, and one of the reasons they had chosen the home initially.

Perhaps the most difficult factor in building a dome house is financing and cutting through the red tape. "The banks don't like 'em," Su-z Allen said. "The banks don't like lending money on something that's virtually indestructible.

Don't ask me why." According to Ansel, it isn't the indestructibility that complicates financing, but rather the uniqueness.

"The banks want comparables within 100 miles, and that's hard to find," Ansel said. "Once someone builds a dome they plan on staying in it."

There are two other concrete dome houses in Clark County. One is at the corner of Charleston Boulevard and Fogg Street and the other is in Bunkerville.

There are quite a few geodesic domes in the valley, but Monolithic Domes founder and President David South notes that geodesic domes have their own issues. Typical geodesic domes are constructed from wood and have 60 flat hexagonal and pentagonal panels arranged to form a dome.

"Because they have so stinking many intersections, they tend to be leakers," South said. "I worked on them for 15 years and finally gave up." Monolithic Domes are one solid concrete dome with junctions only where the dome meets the base.

"We start with this big balloon, which we attach to a concrete ring on the ground," Ansel said. "Then we rough out the windows and spray three or four inches of urethane foam. We embed rebar hangers in the foam and then attach rebar so we have a kind of bird cage on the inside. After that, we spray shotcrete on the inside like an upside-down swimming pool." Shotcrete is concrete applied with a spray gun, which is a century-old technology.

South pointed out that concrete domes have a longer history. "The Pantheon in Rome is a 143-foot diameter concrete dome built in 126 A.D., and it's still in use," he said. South said he's proud of his domes.

"We built a 280-foot diameter dome for a church in Birmingham, Alabama," he said. "It seats 3,500 in just a part of it." Lately, the company has been building more schools.

"They qualify as a tornado shelter," South said. "That's the kind of thing I really like to see."

The Allens opened their under-construction dome home for public tours on Oct. 25. More than 100 visitors checked out the dome over the weekend with a handful wandering by in the days after the open house, as well.

Neighbor Lisa Hardy said she is happy to see the new home going up. "It was amazing when we first saw it," she said. "We can see it from our back porch."

Visitor Rene Hastings said she was inspired by the dome. "We're building a vacation home in Colorado, and I'm going to talk with my husband about doing this," she said. "Why build a cabin when you can have this, and it's energy efficient, too."

Hardy said if the home had the necessities her family would need she might look into dome living.

Hastings summed up the excitement by saying, "Wouldn't this be a cool house to live in?"

Contact Sunrise and Whitney View reporter F. Andrew Taylor at ataylor@viewnews.com or 380-4532.