Custom Building Products has approved FlexBond Premium Flexible Bonding Mortar for use over USG LEVELROCK Brand Floor Underlayments. This new application, the only approved lightweight concrete application by Custom Building Products, is intended to address the needs of professional installers and specifiers who face a variety of job-specific circumstances.

After extensive testing, Custom found that using FlexBond, a premium mortar with maximum flexibility and bond strength, over USG LEVELROCK line of lightweight concrete products helps prevent tiles from cracking due to minor surface movement. LEVELROCK is manufactured by US Gypsum.