Hacker Industries, Inc. has introduced the GYP-SPAN radiant floor underlayment for use over hydronic or electric radiant heating floor systems. Five versions are available, including FIRM-FILL Gypsum Concrete, with a strength range of 1,200 to 1,800 psi; FIRM-FILL 2010, with a strength range of 1,600 to 2,500 psi; FIRM-FILL High Strength, with a strength range of 2,250 to over 3,000 psi; FIRM-FILL 4010, with a strength range of 3,000 to 5,500 psi; and GYP-SPAN Radiant, with a strength range of 1,800 to over 2,500 psi. Hacker Industries, Inc.