What is the best way to elevate and level a sloped floor?
To convert the tapered floor to a level floor at this synagogue renovation outside of Charleston, WV, the architect looked at a couple of different options. The existing floor was tapered for about 22-1/2’ and then level for 9-1/2” ending at steps going up to a raised stage. At the lowest point the floor needed to be raised about 18” to make it level. The project would require approximately 925 cubic feet of fill under the new 4” concrete slab. There were a couple of different void fill options that could be considered. Gravel, sand, and EPS geofoam.
Gravel and sand both weigh between 89 and 108 lbs per cubic foot. Either material would need to be brought in by wheel barrow and spread by hand. The total weight of the gravel or sand fill would be between 82,325 lbs and 99,900 lbs creating excessive strain on the existing slab and the underlying support system. Tamping would be require to compact either material before the concrete slab could be installed, adding even more stress to the existing slab below.
EPS29 geofoam, which was chosen by the architect, weighs just 1.8 lbs per cubic foot. The geofoam for the entire project weighed just 1,665 lbs, which is less than 2% of the weight of sand or gravel. The EPS geofoam was delivered pre-tapered as required, and cut mostly into large panels, so installation was very fast. Any cutting could was done with a reciprocating saw and electric hot wire cutting tools. No tamping was required. There was some trimming involved around vents and corners but the majority of the material just had to be set in place.
EPS29 geofoam is both lightweight and incredibly strong. Weighing just 1.8 pounds per cubic foot, a panel 12” x 48” x 96” weighs under 58 lbs. and has a compression strength of 1,570 pounds per cubic foot at 1% deformation. The panels are easily installed by hand with unskilled labor. EPS geofoam is used in both interior and exterior construction. Most new theaters and theater renovations are done with EPS geofoam. Other uses include infilling swimming pools no longer in service, filling roof deck planters and numerous civil construction applications including road and bridgework.
