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
| Apr 13, 2012
Goettsch Partners designs new music building for Northwestern
The showcase facility is the recital hall, an intimate, two-level space with undulating walls of wood that provide optimal acoustics and lead to the stage, as well as a 50-foot-high wall of cable-supported, double-skin glass
| Apr 6, 2012
Flat tower green building concept the un-skycraper
A team of French designers unveil the “Flat Tower” design, a second place winner in the 2011 eVolo skyscraper competition.
| Apr 3, 2012
Product Solutions
Two new PV systems; a lighter shelf; and fire alarm/emergency communication system.
| Apr 3, 2012
Luxury hotel 'groundscraper' planned in abandoned quarry
Would you spend $300 a night to sleep underground? You might, once you see the designs for China's latest hotel project.
| Apr 3, 2012
SSOE acquires MEP Firm CRS Engineering & Design Consultants
The acquisition will expand SSOE’s Southeastern U.S. presence, broaden CRS’s reach to international markets, and provide both firms’ clients access to enhanced services and resources.
| Mar 30, 2012
18 handy tablet apps for AEC professionals
Check out these helpful apps for everyday design and construction tasks. Our favorite: MagicPlan, which uses GPS to help you measure and draw a floor plan of any room.
| Mar 22, 2012
Hawaiian architecture firm chooses FRP trellis system over traditional materials
MGA Architecture plans to add five more trellis systems on the neighboring building.
| Mar 13, 2012
Worker office space to drop below 100-sf in five years
The average for all companies for square feet per worker in 2017 will be 151 sf, compared to 176 sf, and 225 sf in 2010.
| Feb 15, 2012
Englewood Construction announces new projects with Destination Maternity, American Girl
Englewood’s newest project for Wisconsin-based doll retailer American Girl, the company will combine four vacant storefronts into one large 15,000 square-foot retail space for American Girl.
| Feb 2, 2012
Call for Entries: 2012 Building Team Awards. Deadline March 2, 2012
Winning projects will be featured in the May issue of BD+C.