There was a time when insulating concrete forms (ICFs) were thought of as appropriate only for basement walls. Today, they are used successfully in the construction of everything from an 11-story condominium, in Ft. Myers, Fla., to a Bed Bath & Beyond store in Apple Valley, Minn.
ICFs are stay-in-place concrete formwork made from expanded polystyrene (EPS). The individual units come as interlocking blocks or as larger panels or planks, although the block configuration is the most popular today. The concrete inside a wall built using ICFs can take on different configurations: from a flat concrete plate with foam on both sides to more of a waffle-like structure. Today nearly all ICF systems use the flat plate configuration with plastic ties running between the foam faces. Wall thickness can range from 4 to 12 inches of concrete, depending on the design requirements.
ICF construction proceeds quickly with an experienced crew. The required skill level and training, though, is not that great. According to Jamesway Construction, Toronto, which specializes in commercial ICF construction, "ICF wall construction is not so dependent on hard-to-find licensed trades, therefore work slowdowns or stoppages are less likely." ICF construction also can continue throughout the winter-with the insulated forms, concrete can be placed at temperatures as low as -10° F.
In multifamily residential construction, ICFs present some decided advantages. First, an ICF building is quiet, with nearly complete noise elimination through the wall. This also applies to common "party" walls, allowing adjacent units to be isolated from one another. The strength of a wall built with ICFs also simplifies construction of elevated concrete floors, or composite steel-concrete floor systems such as Hambro's (www.hambro.ws), which is another important quality of life issue in multifamily housing. Flame retardant EPS with fire ratings up to 4 hours also is important in multi-family buildings. ICF walls finished with synthetic stucco or EIFS provide this safety assurance.
Today building multistory structures using ICFs is well understood and bracing systems have advanced to where walls even without intervening floors can rise as high as 50 feet. The Arxx Tall Wall Bracing System, for example, uses patented components with conventional scaffolding to create tall straight walls. Other tall structures have used ICFs as infill on a concrete frame and slab building-for example the 11-story Waterside IV condominiums in Ft. Myers Beach, Fla., the tallest ICF structure to date, was built using Reward Wall Systems' forms.
There are 50 or more different manufacturers of ICFs, which might seem to present a difficult choice, but in reality the choices are not that daunting, especially for multifamily construction where the wise contractor, developer, or architect will choose a company that provides real support. Browse through the ICF Project Files of the Insulating Concrete Forms Association's (www.forms.org) Web site for more information. Manufacturers that have a proven record with multifamily construction are the companies that have experience, conduct training, and provide ongoing support-critical if your construction crew has little experience. "The industry has lots of growth potential as more contractors gain experience," said Joe Lake, president of Eco-Block. "ICF construction is just now getting traction and it's going to be a fascinating transition to watch."
- William D. Palmer Jr. is president of Complete Construction Consultants, based in Lyons, Colo.
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