While rigid foam isn't commonly found on the jobsites of most deck builders, it's become a fairly common residential building material. Most of the time, rigid foam is used for insulation, but it can also be used as a lightweight fill material, such as on this commercial rooftop deck project. Here, blocks of Geofoam EPS (expanded polystyrene) foam were used to help facilitate the makeover of an unused 11th floor roof deck that is part of Prudential Plaza, a 41-story structure built in 1955 in Chicago.
Chosen because their weight wouldn't add significantly to the loads that the roof would have to support, the foam blocks were also compact enough that they could be transported - along with the rest of the building materials - up to the 11th floor via a freight elevator and then through a series of corridors to the jobsite, rather than requiring an overhead crane to lift them into place. The foam blocks were precut and installed according to a layout supplied by the manufacturer, with final trimming to fit onsite. Then adjustable Bison Versadjust pedestals were used to support the pavers and decking.