Expansive, Multi-Tiered Slab and Roof System Utilizing ThermalStar Rigid Insulation
Chicago-area grocer, Mariano’s is known throughout northeastern Illinois for supplying local neighborhoods with fresh, high-quality foods from around the world at affordable prices. Store concepts center around fresh product offerings, high-quality merchandising, and world-class customer service. An important part of meeting that mission is becoming a community asset by creating an authentic shopping experience that is integrated with the neighborhood it serves.
In an urban phenomenon known as a food desert, many densely packed residential neighborhoods lack local access to fresh, healthy produce, meats, fish, and dairy. In 2014 an opportunity to build a new 74,800-SF Mariano’s in Chicago presented itself, thanks in part to a $5 million Build Illinois bond. The chosen location, formerly The Chicago Housing Authority’s Ida B. Wells building, was a tight urban site situated directly in the middle of a residential community. To maximize the limited footprint, the new store incorporated a rooftop parking garage into the building’s design, which necessitated split-slab construction.
Atlas Molded Products supported this project with molded polystyrene rigid foam as a lightweight, long-lasting, insulation solution. Incorporated to eliminate thermal waste across the whole of the expansive, multi-tiered slab and roof system, molded polystyrene insulation is known for high compressive resistance, durability, and cost-efficiency. As a partner in success, Atlas Molded Products also enjoys taking a supportive role in logistics and sequencing to the project’s benefit, whenever, and however, we can.
Fundamentally, the challenges of this project reside in the complexity of inserting a nearly 75,000-SF grocery store into an existing neighborhood with minimal disruption. The tight site led to the decision to put the parking garage on top of the building, which created several design and construction implications for the project. For starters, the grocery store space beneath the garage needed to be efficiently conditioned to the desired interior temperature. Doing so cost-effectively required high-performance insulation. Because the insulation was going to be sandwiched between the roof’s waterproofing system and the concrete parking garage above it, the material also needed to be able to support the live loads of vehicular traffic.
The tight site and challenging building configuration also posed a few complications for the general contractor. Not only did the chosen insulation need to be thermally effective and functionally strong, but between the purchase price and installation costs, it also needed to be the best value possible. Within the design documentation, architects originally specified XPS rigid foam insulation, a material that performs similarly to molded polystyrene foam insulations but is more labor-intensive during construction due to limited size availability. Finally, the tight site meant very limited right-of-way access during construction for off-loading materials from the street and no room for any onsite storage.
Molded polystyrene rigid foam enters the picture as a cost-effective durable, strong, versatile, high-performance in-wall, roof, and perimeter foundation thermal insulation. ThermalStar Rigid Insulation, manufactured by Atlas Molded Products from molded polystyrene and the originally specified material, extruded polystyrene or XPS, are both made from the base material polystyrene. However, each is manufactured through different processes that produce materials with distinctly different characteristics. XPS insulation gradually off-gases blowing agents using during the manufacturing process, which effectively diminishes the material’s in-service R-value. ThermalStar Rigid Insulation provides owners and builders with stable R-values between 4.2 and 4.5 per inch of thickness. If exposed to water, ThermalStar Rigid Insulation dries quickly, further facilitating its ability to maintain established R-values for the entire lifecycle of the building.
ThermalStar’s comparable compressive strength made the decision to switch from XPS to molded polystyrene. The need to supporting the live loads of vehicular traffic was also an important consideration. ThermalStar Rigid Insulations are manufactured in compressive strengths ranging from 15 pounds per square inch (psi) up to 60 psi. In the case of Mariano’s, 40-psi insulation was used to cost-effectively support the live loads with a solid material base.
ThermalStar also differs from XPS materials significantly in the ease of construction and product durability. While the purchase price of XPS and molded polystyrene materials are roughly the same per square foot, XPS materials are manufactured in flat sheets and limited thickness options.
ThermalStar on the other hand can be provided as large as 40-inches thick, greatly reducing the time and effort required to assemble depth profiles of more than a few inches.
Finally, as a partner in our client’s success, Atlas worked with the general contractor to sequence and execute a just-in-time delivery system, whereby pallets of Thermal Star Rigid Insulation would arrive on the backs of flatbed trucks and be off-loaded directly from the truck to the rooftop installation site in a single pick. This allowed the contractor to limit roadway congestion due to construction.
ThermalStar Rigid Insulation from Atlas Molded Products is a durable, reliable, versatile building solution to a wide range of common insulation and structural loading challenges. Coupled with Atlas’ second-to-none commitment to customer service and thoughtful contributions to a well-engineered and orchestrated construction program, the potential applications of these products are nearly unlimited. Confidence in construction comes from certainty in cost, quality, scheduling, and safety. ThermalStar from Atlas Molded Products checks all the right boxes.