Southern Nevada�s Nellis Air Force Base is trimming construction costs of a new child development center by nearly 4% by using a unique aerated plastic-riser foundation system.

Graphic: Courtesy USAF

Cobblestone Construction, Las Vegas, broke ground on the $7.2-million design-build project in August 2010 and later discovered that the six-acre site along the northwest edge of the base was contaminated with radon.

The 26,000-sq-ft block building consequently required a gas ventilation system, which typically comprises a vapor barrier consisting of a membrane of washed rocks and liquid as well as perforated pipe and fans. Wright Engineers, Las Vegas, proposed a cost-effective alternative called Cupolex, which saved $10.97 per sq ft, or $285,000 in materials.

There is also a savings in labor, eliminated by an installation learning curve, says Tony Mateus, Cobblestone project superintendent.

Invented and manufactured by Italian-based Pontarolo Engineering S.p.a., the standard Cupolex unit is a 22-in.-sq recycled plastic dome. A configuration of voids creates natural convection, which eliminates the need for fans, gravel and pipe without compromising structural strength.

�It�s the same principal as the dome,� explains Wright Engineers CEO Brent Wright. The 28-ft-tall single-level building uses 6,800 Cupolex units laid out in a grid across the foundation footprint.

�Workers toss the lightweight risers like Frisbees and then snap them together,� says Wright Engineers President Daniel Bartlett. Using Cupolex instead of a traditional slab-on-grade foundation saved 77 cu yd of concrete (20%) and 2,000 lbs of reinforcing steel (20%).

The system replaces reinforcing steel with wire mesh, eliminates 21 electric fans and reduces subgrade-gravel needs by 90 truckloads, or about 925 cu yd.

Although widely used in Europe, Cupolex is fairly new to the U.S.

The product required testing and review by the U.S. Army Corps of Engineers before gaining project approval.

�This is the product of the future,� Wright says. The project, meanwhile, is on time, under budget and scheduled to open in August 2011.