CTLGroup was retained by BauerLatoza Studio to assist with exterior repairs to the slate roof of Davenport Hall at the University of Illinois in Champaign-Urbana. The project consisted of replacement of slate roofing tiles on the steep sloped roof and investigation of the replacement tiles during installation. As part of the investigation, CTLGroup conducted laboratory testing of the replacement tiles to evaluate concerns regarding the breaking load of the new replacement slate delivered to the project. Physical requirements of roofing slate identified in the specification included the minimum breaking load, maximum water absorption, and the depth of softening (water resistance). Standard test methods used to evaluate the slate samples included ASTM C120 – Flexure Testing of Slate; ASTM C121 – Water Absorption of Slate; and ASTM C217 – Weather Resistance of Slate. CTLGroup determined that based on the results of the laboratory testing, the product submitted for replacement tiles met the physical requirements for breaking load, absorption, and depth of softening for a Grade S1 roofing slate as defined in the specifications.