Homeowners who think outside of the traditional box with wooden frames rely on creativity when building houses with precast concrete elements.
According to James Baty, executive director of the Concrete Foundations Association based in Mount Vernon, Iowa, not only is concrete used in substandard applications, but it also shows its durability and energy efficiency from the ground up in new home construction.
“It’s hard to beat the thermal performance, storm resistance and sustainability of concrete,” he said. “A concrete house built with the right supports can easily last 200 years and, as in the fairy tale ‘The Three Pigs’, withstand nature’s ‘huffing and puffs’ better than a house made of sticks.”
Concrete consists of cement, a fine powder made from limestone, clay and / or slate. When mixed with water, cement 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 building better, stronger, and stronger concrete – especially when it comes to precast grade.
Concrete log homes were once almost synonymous with Florida when post World War II developers sought to build affordable homes that could withstand the state’s hurricane-hit 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 dwindled.
“Working with concrete blocks is brutal on your back and arms,” said Cortie. “They had fewer and fewer workers who would want to do this or get a straight wall right up, so the cost went up significantly.”
Cortie, who served as HabiJax’s COO for several years before joining the DuraBild team last month, said precast concrete houses used to be referred to as tilting devices because a crane was required to get the walls into position. However, changes in concrete production have resulted in a product that is easier to work with while still maintaining the same high levels 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 an innovator in precast concrete systems since its inception, said Company President Jim Costello.
The pre-cast concrete process is a process of making wall panels under factory controlled conditions according to architectural plans and assembling them on site, Costello said. “Instead of pouring concrete into molds on site, our products are reinforced concrete walls with insulation inside for maximum energy efficiency,” he said. “Precast concrete is up to 10 1/4 inches thick and can be up to 12 feet high with custom-made holes so shapes can easily be bolted together for a tight seal.”
As precast concrete that can withstand up to 5,000 pounds per square inch after a 28 day curing process, precast concrete wall panels do not need to retain a functional gray color. Texture can also be achieved in precast concrete shortly after it has been poured into molds by stamping – a process of pressing patterns into wet concrete. Dyes can be spread on stamped, wet concrete so that the outside of the panels can emulate stone or brick. Or after the house is built, skilled masons can apply stone or masonry to concrete slabs.
The foam insulation is layered in each prefabricated form and acts as an impermeable barrier to water and air. Precast concrete elements serve as a solid wall structure and are screwed together for underground applications and multi-storey houses. When the precast concrete parts are put together according to architectural plans, they form a tight building envelope that is recognized for its energy efficiency.
“There is a higher concentration of concrete houses in Europe, while concrete houses in North America can have 15 to 25 percent more front-end costs than traditional new builds that use wood,” Baty said. “However, we are finding that more and more people are considering building concrete houses in storm-prone coastal regions and in places where tornadoes are common.”
On site, DuraBild is the exclusive supplier of structural concrete insulation panels (SCIP) for Northeast Florida.
SCIPs are prefabricated, lightweight structural sections that consist of an insulated polystyrene insulating core that is sandwiched between two layers of steel-welded, galvanized wire mesh.
After the SCIP panels are placed and secured, a low pressure pump is used to apply a high strength Portland cement based mortar mix at 4000 psi (also known as shotcrete or gunite). 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.” It’s a big factor in energy efficiency. “
An energy efficient home in Litchfield, Connecticut, built from precast concrete 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 SCIP-style house including the roof.
The company is currently working on a horse stable near Ocala where the owner wanted a hurricane-proof structure for several award-winning Thoroughbreds.
Precast concrete is structural but also serves as a finished surface on the outside of the house. Since the low-maintenance 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 rebars in each stud and isolated access holes for easy wiring and installation. Inside the house, galvanized steel post cladding is ready for drywall or plasterboard finishing, so interior walls hide the solid ice-cold nature of concrete.
Careful planning is important if you want to build a concrete house from prefabricated walls, as the walls will be embedded in concrete after pouring. “The nice thing about concrete is that it can be molded into all different 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, visit SuperiorWalls.com. To learn more about SCIP-built homes and other structures, visit DuraBildSolutions.com.
In-house editor Anne Hammock contributed material to this story.