Mary G. Pepitone / Universal Uclick
Homeowners who think beyond the traditional wood-framed living box let out their creativity when building houses with precast concrete walls.
As well as being used in underground applications, concrete demonstrates its durability and energy efficiency from the ground up in new build, according to James Baty, executive director of the Concrete Foundations Association based in Mount Vernon, Iowa.
“It’s hard to beat the thermal performance, storm resistance and sustainability of concrete,” he said. “A concrete house that is built with the right supports can easily last 200 years and, as in the fairy tale ‘The Three Pigs’, withstand the ‘snout’ of nature better than a house made of sticks.”
Concrete consists of cement, a fine powder made from limestone, clay and / or slate. When cement is mixed with water, it binds aggregates such as sand and gravel into solid concrete through a chemical reaction called hydration.
But Baty said today’s concrete isn’t your grandfather’s generation – technological advances are making better, stronger, and stronger concrete – especially when it comes to the variety of precast.
Concrete log homes were once almost synonymous with Florida when post World War II developers sought to build affordable homes that would withstand the state’s hurricane-prone weather.
According to Roger Cortie of Jacksonville-based DuraBild Solutions, construction of new log homes began to decline as the skilled workers required to build them decreased.
“Working with concrete blocks is brutal on your back and arms,” said Cortie. “You had fewer and fewer workers who wanted to do that or who could really set up a straight wall, so the costs have increased significantly.”
Cortie, who served as HabiJax’s COO for several years before joining the DuraBild team last month, said precast concrete used to be called tilting because it required a crane to lift the walls. However, changes in concrete production have resulted in a product that is easier to work with while still maintaining the same high level of durability and strength.
Based in New Holland, Pennsylvania, Superior Walls of America is a 35-year-old company with a dozen licensees in the United States and Canada and has been a precast concrete innovator since its inception, said Company President Jim Costello.
The precast concrete process is one where wall panels are made to architectural plans under factory controlled conditions and assembled on site, Costello said. “Instead of pouring concrete into formwork on the construction site, our products are steel-reinforced concrete walls with internal insulation for maximum energy efficiency,” he says. “Precast concrete is up to 10 1/4 inches thick and can be up to 12 feet high with custom holes so the molds can easily be screwed together to create a tight seal.”
A specially formulated concrete that can withstand up to 5,000 pounds per square inch after a full 28 day curing process. A structure can also be achieved in precast concrete walls shortly after pouring by punching – a process in which samples are pressed into wet concrete. Dyes can be applied to punched, wet concrete to allow the outside of the slabs to mimic stone or bricks. Or after the house is built, trained masons can put stones or masonry on concrete slabs.
The foam insulation is layered in each prefabricated form and acts as an impermeable barrier to water and air. Precast concrete parts serve as a solid wall construction and are screwed together for underground applications and multi-storey houses. Assembled according to architectural plans, the precast concrete walls form a tight building envelope that has been recognized for its energy efficiency.
“There is a higher concentration of concrete houses in Europe, while North America concrete houses can have between 15 and 25 percent more front-end costs than traditional new builds that use wood,” Baty said. “But we are finding that more and more people are considering building concrete houses in storm-prone coastal regions and in places where tornadoes prevail.”
On site, DuraBild is the exclusive supplier of Structural Concrete Insulated Panels (SCIP) for Northeast Florida.
SCIPs are prefabricated, lightweight structural profiles that consist of an expanded polystyrene insulating core that is embedded between two layers of steel-welded, galvanized wire mesh.
After the SCIP panels are placed and secured, a high strength Portland cement based mortar mix at 4000 psi – also known as shotcrete or shotcrete – is applied with a low pressure pump. The mortar is then trowelled by hand to achieve the desired finish.
“SCIPs are really the only way other than ICF [insulated concrete form] Block to have a house that is completely airtight, “said Cortie.” That’s a big factor in energy efficiency.
An energy efficient home in Litchfield, Connecticut, built with prefabricated concrete wall panels from Superior Walls, was recently named a winner in the state’s sixth annual Zero Energy Challenge.
In 2015, DuraBild helped complete the first SCIP-built house, the Capri, for elacora and New Leaf Construction. While this house was being completed with a traditional half-timbered roof, Cortie said his goal was to build an entire house in SCIP construction including the roof.
The company is currently working on a horse stable near Ocala where the owner requested a hurricane-proof structure to house several award-winning Thoroughbreds.
Precast concrete elements are constructive, but also serve as a finished surface on the outside of the house. Since the easy-care concrete slabs do not burn or rot over time, they contribute to the durability and energy efficiency of the house.
The panels have vertical steel reinforcement in each stud and isolated access holes for easy wiring and installation. Inside the house, galvanized steel stud walls are prepared for drywall or plasterboard, so that inside walls hide the solid stone-cold nature of concrete.
Careful planning is essential if you decide to build a concrete house from prefabricated walls, because after pouring, walls are set in concrete. “The nice thing about concrete is that it can be molded into all sorts of shapes,” said Costello. “A round house or geodome made of concrete is achievable if an architect can plan it, then we can pour it and build it.”
For information on precast concrete, please visit SuperiorWalls.com. To learn more about SCIP-built homes and other structures, visit DuraBildSolutions.com.
Homes Editor Anne Hammock contributed material to this story.