Insulating concrete forms have a long history of success in low-rise buildings, but now Building Teams are specifying ICFs for mid- and high-rise structures—more than 100 feet. ICF walls can be used for tall unsupported walls (for, say, movie theaters and big-box stores) and for multistory, load-bearing walls (for hotels, multifamily residential buildings, and student residence halls).
Our trusted ICF experts offer the following tips for designing and constructing tall ICF walls:
1. Pre-plan your job by drawing a simple cross section with the ICF you are using.
The cross section will show you how openings line up with the coursing of the ICF joints and where embeds will be placed, says Glen Klassen, regional manager with ICF manufacturer Arxx, Cobourg, Ont. "During the build process, your crew can follow this cross section to know when to stop placing forms and start placing embeds."
2. Account for the ICF formwork course height.
Designers can greatly reduce the amount of formwork cuts the contractor will be required to make by considering the course height of the ICF product when designing the walls, says Kelvin Doerr, VP of engineering and technical services for Reward Wall Systems, Omaha, Neb. Doerr says architects should factor in wall heights, window heights, and floor elevations when possible.
3. Base concrete slump and aggregate size on ICF manufacturer recommendations.
Both concrete slump and aggregate size are impacted by the formwork tie configuration within the formwork cavity, as well as by the amount of open space available around the ties to allow concrete to effectively flow within the forms, says Donn C. Thompson, AIA, LEED AP, CGP, director of Low Rise Buildings with the Portland Cement Association, Skokie, Ill. "Ties with smaller openings will require smaller aggregate to insure the concrete flows effectively through the forms," he says.
Arxx's Klassen offers this rule of thumb: If the concrete is restricted slightly at the top form around the rebar before flowing into the wall, it's just right. If the concrete gets restricted to the point of not flowing down into the wall, it's too low of a slump. If the concrete flows freely into the wall with no restriction, it is likely too high a slump.
4. Consider the STC rating needed for the job.
Once you know the sound transmission class, consider what needs to be added to the ICF wall if an STC rating of 50 or higher is required, says John Krzic, accounts manager with Amvic Building System, Toronto. "For example, by adding a resilient channel to the ICF wall and then installing the drywall, it will increase the STC rating of the wall assembly," says Krzic.
5. Take steps to ensure the concrete completely fills the form.
"One concern with tall ICF walls is that concrete may not fill all parts of the form since the walls are generally thin," says Lionel Lemay, PE, SE, LEED AP, CAE, senior VP of sustainable development, National Ready Mixed Concrete Association, Silver Spring, Md. To help avoid holes and gaps in the concrete pour, Lemay advises the following:
-
Place a single layer of reinforcement in the center of the wall to allow for more space on either side of the reinforcement.
-
Allocate greater spacing of reinforcement than is required in ACI 318 14.5, which requires a maximum spacing of three times the wall thickness or 18 inches, whichever is smaller.
Consider using self-consolidating concrete. "Keep in mind that self-consolidating concrete exerts greater pressure on forms, so additional bracing will be required for most ICF systems," says Lemay.
6. Specify an ICF that is fully reversible.
"These forms have no top, bottom, left, or right side, and, therefore, are more efficiently stacked, reducing construction costs," says Reward's Doerr.
7. Repeat window patterns when possible.
In multistory load-bearing applications such as multifamily, senior living, and hotel projects, try to repeat window patterns from floor to floor so that the openings remain stacked for the full height of the wall assembly, says PCA's Thompson. This maximizes efficiency in design and construction.
8. Make sure, in noncombustible Type I, II, III, and IV multistory building projects, that the noncombustible floor system intersects the foam plastic on the interior of the building.
"The foam plastic must not be continuous from floor to floor, and special detailing is necessary to meet these requirements," says Doerr. In addition, IBC states that interior walls must be covered with a 15-minute thermal barrier. Doerr says half-inch gypsum board will do the trick.
9. Brace from the inside.
The higher the wall, the more difficult and costly it is to reach the exterior of the wall with bracing, says Amvic's Krzic. "Proper bracing will help to ensure that walls will be straight and level," he says. "This is important as it can affect other sub trades, wall finishes, and structural integrity of the building."
More on insulating concrete forms at:
13 tips on working with insulating concrete forms
How Insulated Concrete Forms Help Reduce Energy Consumption
English inspired church built with insulated concrete forms
Related Stories
| Aug 11, 2010
Citizenship building in Texas targets LEED Silver
The Department of Homeland Security's new U.S. Citizenship and Immigration Services facility in Irving, Texas, was designed by 4240 Architecture and developed by JDL Castle Corporation. The focal point of the two-story, 56,000-sf building is the double-height, glass-walled Ceremony Room where new citizens take the oath.
| Aug 11, 2010
Brooklyn's tallest building reaches 514 feet
With the Brooklyner now topped off, the 514-foot-high apartment tower is Brooklyn's tallest building. Designed by New York-based Gerner Kronick + Valcarcel Architects and developed by The Clarett Group, the soaring 51-story tower is constructed of cast-in-place concrete and clad with window walls and decorative metal panels.
| Aug 11, 2010
Dallas Center for the Performing Arts opens
The Dallas Center for the Performing Arts, a new multi-venue center for music, opera, theater, and dance, will open this month, completing the 25-year vision of the Dallas Arts District. Foster + Partners, Rem Koolhaas, Joshua Prince-Ramus, and Skidmore Owings & Merrill are among the architecture firms involved in the development, which includes four venues unified by a 10-acre park.
| Aug 11, 2010
Polshek unveils design for University of North Texas business building
New York City-based architect Polshek Partnership unveiled its design scheme for the $70 million Business Leadership Building at the University of North Texas in Denton. Designed to provide UNT’s 5,600-plus business majors with a state-of-the-art learning environment, the 180,000-sf facility will include an open atrium, an internet café, and numerous study and tutoring rooms—al...
| Aug 11, 2010
School district plans net-zero building
Camas (Wash.) School District is planning to utilize one of three energy sources—photovoltaics, wind turbine, or geothermal—to help take its new community high school completely off the grid. The school district commissioned Interface Engineering to explore all three options for the project, which is scheduled to break ground in August.
| Aug 11, 2010
Cooper Union academic building designed to reach LEED Platinum
Morphosis Architects and Gruzen Samton are collaborating on an ultra-green academic building for New York’s Cooper Union that is designed to achieve LEED Platinum certification. The program for the nine-story facility mixes state-of-the-art laboratories, classrooms, a multipurpose auditorium, and a range of public and social spaces.
| Aug 11, 2010
LA high school takes design cue from historic Mexican architecture
The Los Angeles Unified School District recently opened the $75 million Felicitas and Gonzalo Mendez Learning Center, a high school in the Los Angeles neighborhood of Boyle Heights, near Little Tokyo. Designed by Nadel Architects in a joint venture with Barrio Planners Inc., the 114,000-sf school is vertically integrated, allowing the campus to fit on a compact, six-acre site.
| Aug 11, 2010
Take the hassle out of managing subcontractors
As general contractors look to technology for an edge in the slowing commercial construction market, Web-based bidding programs are helping them to connecting bid information, subcontractors, and proposals. A 2008 survey by the Construction Financial Management Association found that 62% of general contractors participated in Web-based construction bidding vs.
| Aug 11, 2010
Toronto mandates green roofs
The city of Toronto late last month passed a new green roof by-law that consists of a green roof construction standard and a mandatory requirement for green roofs on all classes of new buildings. The by-law requires up to 50% green roof coverage on multi-unit residential dwellings over six stories, schools, nonprofit housing, and commercial and industrial buildings.
| Aug 11, 2010
Carpenters' union helping build its own headquarters
The New England Regional Council of Carpenters headquarters in Dorchester, Mass., is taking shape within a 1940s industrial building. The Building Team of ADD Inc., RDK Engineers, Suffolk Construction, and the carpenters' Joint Apprenticeship Training Committee, is giving the old facility a modern makeover by converting the existing two-story structure into a three-story, 75,000-sf, LEED-certif...