b"T&R Update Examining Highly Reflective Modified Bitumen Systems Dupuis Matt E year, the MRCA Technology and Research (T&R) Committee re year's MRCA conference and that the original inquiry came from Texasach views the state of the industry and considers research opportunitiesbased MRCA members, the T&R committee elected to focus its efforts on to either expand industry knowledge or investigate MRCA members' con Texas roofs only. These roofs certainly see multiple days of extreme heat cerns about certain issues. One of the committee's current research proj that are well above 90 Feven above 109F. and ects does both.To date, the reflective modified bitumen roof study encompasses 28 Early this year, acommittee member inquired about in-service T&Rroofs in Dallas and Austin, TX, although more roof membranes may solar reflectivity of modified bitumen membranes and asked forbe studied. The modified bitumen cap sheet surface solar reflectance is information beyond what is typically provided in a manufacturer'sbeing measured with asolar reflectometer provided calibrated portable, specification sheet. The T&R committee agreed that it was not aware ofand operated by the National Roofing Contractors Association's techniany published studies specifically targeting highly reflective modified bi cal department. tumen systems, although there are published studies on in-service solarThe roofs under study represent aroof ages, manufacturvariety of reflectivity for several classes of highly reflective single-ply membranes.ers, and different manufacturing technologies. Seven different manuPublished Researchfacturers' highly reflective modified bitumen sheets are being studied. By doing a quick Internet search for solar reflectivity and roofReflectometer readings from at least 30 randomly selected areas on each roof are yielding astatistical database. Aof 840 readings are membranes, you undoubtedly will be directed to the Cool Roof Ratingrichtotal Council website (www.coolroofs.org). This organization is an excellentmonths-6 currently being taken from rooftops that range in age from 3 resource for searching and comparing different manufacturers'years. In terms of the different technologies used to achieve areflecproducts on the basis of solar performance. The products are rated inhighly accordance with the Cool Roof Rating Council's standard CRRC-1,tive modified bitumen sheet cap, the study should show, for example, which is prescriptive and incorporates, by reference, several well if highly reflective embedded granules return the highest readings or whether aisthe strongest performer. established ASTM and ASHRAE standards.liquid-coated cap sheet youMatt Dupuis is senior engineer atResearch Inc., Ifreview the specification sheets for modified bitumen systems, identified as cool roof or highly reflective membranes, you likely willStructural Midd/,eton,WT.The results ofstudy will beand find numbers for initial solar reflectance and 3-year aged reflectance, inthispresented discussed by the T&R Committee atMRCA 63rdAnnual accordance with ASTM C1549. Initial reflectance is determined when thethe Conference in Dallas atam on Thursday, December 6 membrane is factory new, whereas the 3-year aged value is a7:30-9 CRRC-1 prescribed aging process, which involves placing membrane specimens in three climate profiles specified by Heating Degree Days and Cooling Degree Days. These include hot and humid, hot and dry, and cool and dry climate categories. CRRC-1 provides examples of locations for each category: Miami for hot and humid, Phoenix for hot and dry, and Chicago for cool and dry. For the study, samples are placed outdoors in racks at a prescribed years slope (ASTM G7). After 3of aging, the samples are subjected to ASTM C1549, the lowest number from the three climates allowed to be reported as the aged reflectivity. Although the prescribed aging process for membranes is generally well thought out and impartial, this relatively small test sample cannot capture all the debilitating conditions faced by aroof. For functioning example, it does not take into account stresses from service such as installation differences, foot traffic, drainage patterns, and rooftop unit exhaust. Only field data from the rooftop can capture these conditions. The T&R Study The T&R Committee elected to conduct aof highly reflective survey modified bitumen roof systems in service. Admittedly an exhaustive , study would cover many geographic regions, building configurations, and membrane types. However, given the Dallas, TX-location of this 8www.mrca.org- Midwe,st Roofer"