b'TECHNICAL & RESEARCHBITEC PhotoHAIL IMPACT TESTING OF MODIFIED BITUMEN ROOF MEMBRANES By Heidi Mase and Richard Koziol of Wiss, Janney, Elstner Associates, Inc.Introduction a single manufacturer of various ages through Wiss, Janney,physical testing and laboratory review and Elstneranalysis. Associates, Inc.Test Program Description(WJE) and theTesting was conducted in accordance with Midwest RoofingASTM D3746, Standard Test Method for Impact Contractors Association (MRCA) Technical andResistance of Bituminous Roofing Systems. Per Research (T&R) Committee have a history ofthe standard, this test method subjects 305 by 305 collaborating to develop research and testingmm [12 by 12-in.] specimens of a roofing system programs that focus on expanding knowledge(insulation and membrane complete with top of commonly used roofing materials. In 2023,surfacing) to a series of four impacts, one in each the focus of the research and testing was onquadrant, from a standard missile falling freely granule-surfaced, modified bitumen roofingfrom a predetermined height with an impact energy membranes. WJE, in collaboration with the MRCAof 30.0 J [22 lbf-ft]. Damage to the membrane is T&R Committee, developed a testing program toassessed by visual examination of the felts after evaluate the influence of hail impact on granule- solvent extraction of the bitumen. surfaced modified bitumen roof membranes installed in a low-slope roof assembly. TheEighteen 12-inch by 12-inch samples were divided objective of the test program was to determineinto four 6-inch by 6-inch quadrants. A 5-pound, the extent of damage to these membranes from2-inch diameter steel missile was released from 38 www.mrca.orgMidwest Roofer'