b'Roof Rot: Ignorance Is an Easy Way to Damage Low-slope Residential RoofsChange often brings with it unintended consequences,In the mid 1990s, researchers (theoretical By Thomas W. Hutchinson, AIA, FRCI, RRC, CSI, RRPand the issue of reflective roof surfaces in Northresearchers with no architectural, engineering, America is no exception. In the late 1990s, U.S. citiesroofing, construction or practical building technology in northern climates started to mandate the use ofexperience or knowledge) at research institutes reflective roofmore for politics, feel-good, pseudo- conducted studies into the effects of minimizing environmental reasons than sustainable, resilient andsolar gain through the roof via a reflective surface. durable reasons. In my estimation, cool roofs often didBased on the researchers algorithmic findings and more to lower the quality of buildings than enhancerecommendations (regardless of their validity), them. Furthermore, code and standard changes wereenvironmental groups used the concept to promote made with no understanding of the result and nochange. Large cities started introducing new energy education to the architects of America. codes with reflective roofing requirements and Although the resulting unintended consequencesprescribed reflectance values. These new codes affected commercial and residential buildings, it wascontained greater insulation requirements, which was the often-catastrophic results on low-slope residentiala benefit. However, in this one code adoption, roof buildings that went untold and left homeowners withsystems, such as coal-tar pitch, that had performed tens of thousands of dollars of corrective work onfor centuries were no longer permitted. Consequently, basically new residences. roofing contractors went out of business and so did Following is a summary of how these concerns evolvedsome roofing material manufacturers because of in wood-framed residential construction. Ive includedunproven and suspect research.case studies of failures, potential solutions and lessonsArticle originally published by Roofing in March/April 2017 HISTORY Vol. 8 Issue 2learned. About RoofingPhotos and Details: Hutchinson Design Group Ltd.During the industrialization of Americas large citiesRoofing is a national publication that unravels, throughout the 1800s, the need for labor causedinvestigates and analyzes how to properly design, install and populations to explode. To house the labor migration,maintain a roof system. Through the voices of professionals in row houses (3- to 4-story structures, often with athe field, Roofings editorial provides a unique perspective. garden level and four or more narrow units) were constructed approximately 3-feet apart, block after block, creating medium-sized apartment blocks. Most of these row houses were wood-framed, masonry veneer with low-slope roof structures. The interior walls and ceilings were finished in cementitious plaster, which provided a durable, fire-resistive finish. The plaster also performed as an effective air and vapor barrier, preventing interior conditioned air from penetrating into the non-insulated walls and ceilings where it could condense within the walls and roof on cold days.Heating costs were low, so littleif anyinsulation was installed in the walls and roof. Roofs were composed of built-up asphalt and coal tar, both smooth and aggregate surfaced. Attic spaces often 4 to 6 feet in height were vented via static vents. Any conditioned air that passed to the attic was able to dissipate through these static vents. This method of construction performed without significant attic condensation, and the roof systems and roof structure served these buildings for decades. t Roofer14 www.mrca.orgMidwes'