There is nothing else like it in Las Vegas, but if Tyler Johns, president of Blue Heron Builders, Las Vegas, has his way, this house will be the first of many concrete homes that blur the line between indoor and outdoor living. Sometimes you have to consciously think about whether you are walking into an interior or exterior room in the 2009 The New American Home (TNAH). Amenities such as televisions and fireplaces in outside areas cause you to wonder if you are indoors, and walls roll away to blend the outside with the inside. All of this is in a concrete house that features exterior walls constructed with insulating concrete forms (ICF). Concrete just isn't a square box anymore.
Bringing the outside in
Las Vegas enjoys times of the year that are ideal for being outdoors. In TNAH one living room wall rolls away allowing residents to move seamlessly to the outside pool deck area where there are both shaded and open areas to relax.
The four-story home features outside decks off each story level. With all the emphasis on indoor-outdoor living, the house also can be closed to the outside and heated or cooled efficiently. The ICF walls boast an R50 value and the glass windows reduce the amount of infrared radiation transmitted inside. Using ICFs was better than “plain” concrete—it gave the house two built-in layers of foam insulation.
This concrete house
At 8800 square feet (20,000 square feet if you include the outside living area), the construction used 1000 cubic yards of concrete. The concrete work included the footings, exterior walls (including walkout basement walls), basement and first floors, diamond-polished garage floors, and 1500 square feet of walkways and patios built with precast concrete pavers cast to look like real stones. It also included concrete block perimeter walls, a 12-foot-high waterfall built with concrete blocks surrounded with cultured stone, outside walls finished with stucco, and a swimming pool and deck.
Design Concrete of Nevada, Las Vegas, installed the footings and ICF walls for the house. The site turned out to have a high water table resulting in the builder, Blue Heron, excavating an additional 6 feet of soil and replacing it with fill compacted in 1 foot lifts. Vapor barriers also were included. Will Nelson, the general manager for Design Concrete of Nevada, says there was water in their footing holes so they ran a sump pump during concrete placement.
Design Concrete of Nevada constructed the exterior walls using ARXX brand ICF forms—a sponsor for the project—and placed the concrete. They used 8-inch- and 10-inch-thick concrete walls for the basement level and everything aboveground was 6-inch-thick ICF construction. The walls for the top floor of the house—the observatory level—featured wood-frame construction. The walls that roll away and open the house to the outside also were framed in wood, creating space for the “pocket style” walls to slide into. But Nelson says that 90% of the exterior walls of the home were built with ICF.
The concrete used in the walls consisted of a 4500-psi mix with fly ash and a superplasticizer. Nelson says the water-cement ratio was 0.45 and that the placements went smoothly.
Both the concrete basement floor and first floor deck were post-tensioned (PT) reinforced. This isn't unusual in Las Vegas for slabs on ground, but the first level floor was 8 inches thick and the PT greatly increased its structural capacity.
The shear numbers of window and door bucks that had to be placed accurately into the forms was a major challenge. The multiple high walls with different thickness also added to the job complexity. Nelson says there were constant measurement issues but they worked closely with the framing carpenters and resolved problems as they occurred.
Design Concrete of Nevada specializes in ICF construction in the Las Vegas area, so they own a lot of scaffolding—bracing forms unique to the ICF industry. But for a house this size, they also needed to rent additional scaffolding.