The house is so peaceful that Michael and Susan Mullendore had to install microphones to hear the outside brook trickling through the yard.
"It's wonderfully quiet; still and quiet," Susan said of her Ellicott City home.
Indeed, the strength of the Mullendore home fosters a comforting inner silence. Why? Well, the answer is fairly concrete.
The Mullendore home is made of a concrete-polystyrene combination, or ICF, for "insulated concrete form." The Mullendores chose it because of its anticipated energy savings, quality and strength.
"We expect it to go nowhere," she said. "It's solid and wonderful."
They took concrete about as far as it goes -- even choosing concrete counters and splashboards for the kitchen.
Television meteorologist Bob Turk and his wife, Tina, picked an ICF system for their new home in Phoenix. During a hurricane conference in Florida, Bob Turk learned about the systems, researched the varieties, and chose the ECO-Block brand.
The Turks were impressed with the strength of the material, its energy efficiency and the idea that the system -- since it's not wood -- doesn't involve chopping down trees.
"All things considered, it just made sense," said Tina Turk. "This is a strong house. It's energy-efficient. We had to downsize our [current] heating system three times."
Now the Turks recommend the system to everyone -- even for home additions.
Concrete converts Bob and Deb Bollinger estimate that they will pay only $40 to $60 per month in propane gas bills -- even in winter -- for their 3,100-square-foot, concrete-polystyrene home nearing completion in Reisterstown.
"It's like using cast iron vs. plastic piping in plumbing," Bob Bollinger said. "Cast-iron pipe is a dinosaur now. The plastic is better. And it's better to have this [concrete] construction."
ICF construction is gaining popularity. Questions remain and research results are still coming in, but many builders have been won over by its benefits. ICF is also becoming a competitive industry with more than 20 brands on the market.
The Illinois-based Insulating Concrete Form Association says 20,000 homes across the country have been built using ICF, in terms of above-grade walls. Though particularly popular in states with rough weather such as Florida and Texas, the construction is spread fairly evenly across the country.
ICF President Dick Whitaker predicts that half the new homes in the United States will have ICF framing within 10 years.
Building with ICF construction is fairly simple, though it takes crews two to three projects to really get the hang of it, various builders say.
Individual, hollow polystyrene blocks are stacked to form the skin of the walls. They're reinforced with steel rods and linked together with plastic studs. Steel used in the foundation extends into the wall system to form an interlocking bond, anchoring the home to the ground. When the wall is ready, concrete is poured through a big hose from the top of the wall -- filling the wall cavity from bottom to top.
Somewhat like Lego blocks
Many ICF systems look like foam Lego blocks when they're being assembled. The process still shocks some building inspectors -- and getting approvals can take a little longer than normal.
"They said we couldn't build out of foam," said Bob Bollinger. "My wife told them it was concrete. They got another inspector out and he OK'd it."
"Anyone who sees it is pretty impressed -- through common sense," said Bruce McIntosh, spokesman for the Portland Cement Association, based in Skokie, Ill. "The process eliminates a lot of steps. There's no sheathing, no [fiberglass] insulation -- and there's a lot of stability. It's a monolithic pour."
After it's poured, the concrete makes a "phenomenally strong" wall, said Lee Yost, president of Advanced Building Systems of Monkton, which markets the ECO-Block and resulting "superhomes." Yost was in charge of the ICF system in the Turks' home.
The idea is that the concrete provides the strength and silence as well as better fire and storm resistance.
The polystyrene provides the insulation and moisture protection. No other insulation is required. Competing systems are similar, though they may have variations on the type of polystyrene and type or shape of the blocks.
"It's like wrapping your home in a cooler," Yost said.
After the walls are poured, drywall and siding can be screwed into indentations in the polystyrene, and attached to the concrete. The concrete actually cures as it sits in the blocks. Siding can be anything from stone to vinyl.
Horizontal tubing is run through the walls so that electric wires can be channeled to the outside of the house. Inside wiring is run through channels cut in the polystyrene. Contractors can even run drainpipe to the basement.
There are a few extras involved. Fresh-air exchangers are required because the homes are so dense and air-tight. This keeps radon levels safe, too, Yost said.