EPS Rigid Insulation Protects an Iowa Recreation Center from the Elements
During the winter of 2007 – 2008 in Iowa City, IA a heavier than normal snowpack was followed by frequent and intense rainfall that caused the Iowa River to swell. Officials at the University of Iowa began to fear for the Voxman School of Music Building, sited just steps from the bank of the Iowa River. Eventually, the University’s worst fears were realized, and what was later deemed to be a 1,000-year flood destroyed the building beyond repair.
Six years later, in the summer of 2013, the University embarked on the state of Iowa’s first-ever design-build contract to construct the Hawkeye Tennis and Recreation Center Complex. Programmed to provide indoor practice space for the University’s marching band as well as the tennis, golf, and softball teams, the new $15 million facility features 82,000-square feet of artificial turf that had to withstand the climactic rigors of Iowa’s harsh winters and hot summers.
As a design-build project, the general contractor led the entire project team including the architect to streamline costs and schedules while making design and material selection decisions in a forward-thinking process. Atlas Molded Products supported project success as a customer-focused manufacturer of molded polystyrene insulation, which provides reliable thermal insulation that performs well in any climate and frequently saves both time and money in installation compared to other rigid foam insulations.
The Challenge
Throughout the year, Iowa’s intense temperature swings range from well below zero during the winter to more than 90 degrees in the summer. Economically heating and cooling a metal building roughly the size of a football field was no small order for the University and efforts to decrease long-term operational costs had to be evaluated carefully during design development. For a multi-purpose, open-span space of this size, the project team determined that a crosslinked polyethylene in-floor radiant heating system provided a lot of advantages over forced-air heating. Rather than blowing warmed air into space from above, radiant heating works by embedding a grid of plastic tubing into the building’s concrete floor, through which a warm liquid is circulated to warm the building from the ground up. Because controlling the direction of the heat’s dissipation is an important factor in maximizing the benefits of radiant heating, the tubes are placed on top of a layer of rigid foam insulation that acts as a thermal barrier between the concrete slab and the ground below.
The Solution
Leveraging the design-build contracting process to the fullest, contractor, Russell Construction + Development, wisely solicited value engineering recommendations from subcontractors during project development. In consideration of both first term-construction costs and long-term operations, it was the subcontractor responsible for the artificial turf scope of work, MBA Incorporated (MBA), that suggested molded polystyrene rigid foam insulation as a cost-saving alternative to the originally specified extruded polystyrene (XPS) insulation.
While both molded polystyrene and extruded polystyrene insulations begin with the same base product, polystyrene, from there the manufacturing process diverges significantly. The molded polystyrene rigid foam insulation made by Atlas Molded Products is first expanded using a blowing agent with low global warming potential, which is replaced with air shortly after manufacturing. The polystyrene particles are then molded into large blocks of material, which are then cut into sheets of insulation. XPS insulations, on the other hand, use hydrofluorocarbons with a much higher global warming potential and are manufactured in a continuous extrusion process that produces individually made sheets of insulation. Long after the insulation manufacturing process is complete, while the air used in molded polystyrene remains, the hydrofluorocarbons used in XPS slowly dissipate leaving a void in the insulation that is then filled by air. The net results of this off-gassing are that hydrofluorocarbons, which have a high global warming potential, are released into the Earth’s atmosphere and the actual in-service R-value of XPS insulations decrease making them less effective over time.
The recommendation to switch from the XPS insulation originally specified to molded polystyrene from Atlas Molded Products saved the project an estimated $100,000 in material costs for the 80,000 square feet of insulation. The insulation’s compressive strength was also a significant consideration since the design called for adding a six-inch layer of rock aggregate on top of the material before placing the artificial turf. Doing so necessitated driving fully loaded dump trucks out onto the floor of the building with only the foam and a thin layer of rock and dirt to support the heavy equipment. Atlas manufactures molded polystyrene across a range of compressive strengths that begin at 10 pounds per square inch (psi) and go up to 60 psi. The high strength 60 psi molded polystyrene was able to support the significant loads required in this facility.
Though the design-build methodology stretches back to antiquity, for the University of Iowa it was an unfamiliar process. With the unfamiliarity came a certain sense of unease, especially where long lead-time item materials like the molded polystyrene were concerned. MBA was required to provide actual photographic proof of their purchase order to the University showing they would have the full 80,000 SF of material on hand and ready to install before need. Due to the volume of material required and limited onsite material storage space, MBA worked with Atlas on pre-purchase verification and then Atlas stored the entire order until the building foundation was ready.
Molded polystyrene’s ease of installation also came into play. MBA was able to engage members of the local high school football team to help with installation as a fundraising project. Under MBA's guidance, approximately 20 players from the football team installed all 80,000 SF of insulation in a single day, tallying roughly 250-man hours of labor while eating about $300 of pizza. MBA used an Apache Dual Plane Laser System with a tractor-mounted grading box to ensure a precisely finished grade. Once the insulation was installed, the cross-linked polyethylene tubing for the radiant heating system was easy to place and secure to the foam using u-shaped flush mount clips.
The design-build contracting method allows designers, builders, and subcontractors to incorporate collective knowledge to make beneficial decisions on project specifics. In the case of the University of Iowa’s Hawkeye Tennis and Recreation Center, a single material substitution suggestion saved $100,000 in product costs and led to a fun, easy way for local youth to gain hands-on experience participating in a community-enhancing project. Atlas Molded Products is proud to partner with clients, designers, builders, and specialty contractors in Iowa and around the country to pre-think construction challenges to solve problems, save time and money, and ensure long-lasting, operationally efficient thermal comfort on projects big or small.
