The following information is provided for the guidance of the rink owner and concrete contractor building a roller skating rink subfloor to receive an epoxy plastic skating surface. Because the epoxy subcontractor can't know the general conditions of every area of the country or the specific conditions for each site a rink will be constructed on, the subcontractor can't be responsible for the final condition of the subfloor. The rink owner and concrete contractor can provide a moisture-free and level concrete subfloor using the following guidelines. The concrete contractor should take whatever precautions local conditions warrant to guarantee the concrete subfloor is moisture-free and level. Sample core testing of soil conditions should be mandatory on all sites to determine soil compaction and location of the water table if any. Compaction of the subgrade under the slab is very important to prevent settlement and cracking of the subfloor at a later date. After proper compaction, 4 to 8 inches of granular subbase material, such as clean crushed stone, should be placed, rolled and packed repeatedly. A primary objective is a moisture-free concrete subfloor. This can be accomplished in a number of ways. First, a vapor barriers with a permeance of less than .3 is mandatory. The slope of the landscaping must be away from the building. The use of drain tile around the building and under the floor is highly recommended as an additional measure to ensure a moisture-free slab. The surface of the concrete slab should be machine troweled to a smooth but no slick finish. After troweling, the slab should be broom finished to provide a better texture for adhesion of the plastic. Special care must be taken to avoid trowel ridge lines or an extremely rough broom finish as this will have a definite effect on the ultimate skating surface. Again, it cannot be stressed too strongly: the levelness of the subfloor and condition of the concrete finish play a leading role in the success of the final epoxy skating surface.