Making the Business Case for Building with Insulated Concrete Forms: Energy, Safety, and Savings
Case Study: West Village Student Housing at Texas Tech University, Lubbock, Texas
Photo courtesy of Mackey Mitchell Architects (left); photo courtesy of Fox Blocks (right)
Shown is the West Village Student Housing at Texas Tech University completed (left) and under construction (right).
A design-build project with Whiting-Turner, BGK Architects, and Mackey Mitchell Architects, this 230,000-square-foot West Village Student Housing complex at Texas Tech University implemented fast-track construction methods to deliver the project within an incredibly compressed schedule: 16 months for design and construction. Opened in 2014, this $54.8-million complex contains 455 beds, community lounges, conference rooms, and designated study rooms. It was designed to meet LEED certification, serving as a model for Texas Tech’s newly adopted sustainability initiatives.
Expected to reduce energy consumption by at least 20 percent over a typical residence hall, West Village utilized insulated concrete form (ICF) walls and precast hollow core floors, which delivered a highly energy-efficient, structurally solid, exceptionally fire-resistant, and acoustically sound dormitory. Another key aspect of the project was indoor air quality. Expanded polystyrene (EPS) is a stable and durable material ideal for construction. No chlorofluorocarbons, hydrofluorocarbons, or formaldehydes are used in the manufacturing process, and there is no off-gassing.
ICFs in Combination with Other Floor and Roof Systems
There are many options for floor systems that integrate well with ICF wall systems. ICF walls are simply concrete bearing walls, so any floor system that is used for other types of bearing-wall construction can be used in combination with ICF wall systems. These include traditionally formed reinforced concrete slabs, ICF slabs, precast hollow-core plank, concrete on metal deck combined with steel joists, or cold-formed joists. Wood framing systems for floor construction can also be adapted for connection to ICF walls using embedded ledger bolts.
Six Construction Steps
Photo Courtesy of Nudura
The construction process when building with insulated concrete forms (ICFs) is simple, which is why construction is cost-effective. Once the foundation or structural floor is in place, these steps are followed:
Step 1: ICFs are stacked in the shape of the wall, and openings for windows and doors are formed using bucks made of treated wood or plastic.
Step 2: Steel reinforcing is placed into the forms and secured in place.
Step 3: Bracing and scaffolding are installed to keep the wall straight, plumb, and secure and provide a working platform.
Step 4: Concrete is pumped into the forms.
Step 5: Electrical and plumbing lines are installed into the expanded polystyrene (EPS) by cutting channels with a hot knife or another tool.
Step 6: Interior and exterior finish is installed directly to the ICFs by screwing into the embedded plastic furring strips.
When building multistory buildings, the walls are generally erected and cast one story at a time. Structural floors are installed and finished before continuing with walls on the next level. There are also examples of walls being placed several stories at a time and installing structural slabs later. Some contractors have panelized ICF walls off-site to further reduce construction time. Others are beginning to use steel fibers in place of horizontal shrinkage and temperature reinforcement, which can also significantly reduce construction time.
When to Use ICFs
ICF walls are best suited for bearing-wall-type construction. If the architectural style for the building is to be floor-to-ceiling glass with large cantilevered balconies, traditional concrete flat-plate construction is the best option. However, if the building is a typical apartment building, hotel, dormitory, or assisted living facility with a significant solid exterior wall that includes punched window openings, ICFs are the ideal solution. Generally, these types of buildings have a rectangular floor plate with the elevator located in the center. Longitudinal corridors service living units on either side. Each unit has a solid wall both on the exterior and at the corridor, making them ideal to function as structural bearing walls.
Furthermore, since multifamily construction requires fire barriers between dwelling units, ICF walls create a superb demising wall. Besides providing superior protection from spreading fire (2 to 4 hours), ICFs also have excellent noise-attenuation properties. Whether designing an apartment complex or hotel, both fire safety and noise reduction are always concerns. Energy efficiency is also a major concern for apartment owners and hotel operators. ICF concrete buildings benefit from the lower energy bills resulting from the high-performance envelope.
When to Consider ICFs
ICFs should be considered for any building that has a long-term owner, such as a build and hold developer or a government entity. Generally, because these forms and the wall system become so energy efficient, locations, where the latest energy codes have been adopted are well-suited to building with ICFs. They are also well-suited to any kind of a wall system that has many punched openings, as the energy codes are now forcing buildings to adopt such openings, especially in multifamily construction. Any place where resilience (to fire, wind, earthquakes, and/or flooding) is an issue is also ideal for building with ICFs.
In the past, short-term building owners or build and sell developers—who oftentimes are not concerned about long-term value and are more concerned about short-term costs—usually built with the cheapest form of construction: wood frame. However, with recent spikes in soft-wood lumber prices, ICF construction has become first-cost competitive. If the building is in a location where energy codes are outdated (which is becoming rare), constructing a highly energy-efficient building might become less compelling if the builder is intent on selling the building.
As mentioned previously, curtain walls are better suited to concrete-frame construction than ICFs. However, some structures with curtain walls have been built using ICFs, where ICFs more or less form a frame around the exterior and then spandrel glass is used in front of the ICFs.
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