January 18, 1998
For Immediate Release

New Home Buyers Find Concrete Ways to Leave Their Lumber

There are many reasons a homeowner might choose to build a new home in concrete: to achieve superior soundproofing, to avoid termites and rodents, to gain environmental benefits or to reap energy savings. No matter what the reason, more and more homeowners are upgrading with concrete as rising lumber costs close the price gap between stick-built construction and concrete.

In conventional poured-in-place construction, a crew erects forms of plywood or steel that make a mold in the shape of the desired walls. After placing rebar to reinforce the wall forms, the crew pours concrete inside the cavity. Once the concrete hardens, the crew strips the forms to leave the reinforced concrete walls.

In ICF systems, the polystyrene form is internally secured to the concrete with plastic ties and left in place. There it serves as thermal and acoustical insulation, an air and vapor barrier, exterior wall sheathing, and, in some cases, wall studding.

How they work
ICF systems are produced with expanded polystyrene containing up to 20 percent recycled materials. Units typically provide 2 inches (5 cm) of insulation on both faces of a concrete wall, which is usually 6 inches (15 cm) thick. The result is a solid 10-inch (25 cm) assembly with strong thermal properties that holds down energy costs. The integral, permanent insulation allows builders to create super-efficient insulated walls—from R-20 to R-56—in a fraction of the time required with wood or steel frame.

Two basic types of ICFs are available. One uses hollow, polystyrene blocks that stack and interlock almost like Legos, and the other uses panels or planks that are held a constant distance apart by a series of plastic ties. Several brands of ICFs are available in almost every region of the U. S. and Canada.

After adding vertical and horizontal reinforcement, contractors pump concrete into the cavity to create a solid structural wall with polystyrene insulation on both sides. Once crews complete the wall, electricians cut paths for cables and wires into the polystyrene forms. Plumbers work in a similar way, placing cold and hot water lines in the insulation after the concrete is poured, while drain lines inside the wall are installed as sleeves before placement.

The insulation provided by the polystyrene forms also gives builders the ability to successfully place concrete even during extremes of weather. Few weather conditions affect a pour because the form insulates the concrete, allowing it to cure almost regardless of outside temperature or humidity. During construction, the forms function like thermos bottles—the insulation forces the water to leave the concrete at a lower rate, diminishing the risk of serious cracks developing.

Polystyrene forms can be cut to any shape to allow for unique home designs or site conditions. Since the systems provide a flat, continuous surface to work on, troweled or painted finishes generally go onto polystyrene forms with little advance preparation. Stucco siding may be applied directly over the exterior surface. Brick ties are easily installed before concrete placement and yield a strong and beautiful brick veneer finish. Sidings that can be screwed on, such as vinyl and aluminum, readily attach to systems with the help of fastening surfaces. Even sidings requiring nailing can often directly attach to fastening surfaces made of plastic or wood.

Currently, insulating concrete forms are only used to build walls, although several manufacturers are designing additional forming components that will allow the construction of attached concrete floors at the same time.

Information made easy

For consumers or builders looking for up-to-date information on ICF products and local contacts, try calling the toll-free hotline at (888) 333-4840 or checking out the web site at www.concretehomes.com.

> Return to top

 
Careers | Sitemap | Disclaimer | Privacy Policy | © 2009 Portland Cement Association - All Rights Reserved