b'STEEP SLOPEvolume is not simple or always practical. Attic 9entilation DiagramHaving T roubleshooting OptionsIna2009American SocietyforTestingand Materialspapertitled Compact Asphalt Shingle R oofSystems:Should They Be V ented, authors Peter E. Nelson and Jason S.DerAnaniannoted, The longevity of the roof assembly also relies on the occupant s ability to identify whether leakage or wetting is occurring and to provide leak repair. If the leakage is concealed or unnoticeable, the damage will go undetected.Whilenoonewants something to go wrong inside the attic, the fact is it s an application advantage to be able to visually inspect a vented attic for signs of trouble. If spray foam insulation is installed along the underside of the roof deck in an unvented attic, how can a troubleshooting inspection take place? The potential consequences of an undetected leak or moisture problem canbesignificantbothintermsof damage and cost.Year-RoundPerformanceinAllSoffit 9entsClimatesShingles that are installed on unvented roof assembles operate at slightly higher temperatures,roughly2-3degrees Fahrenheit warmer than shingles on vented assembles. This can reduce their service life by roughly 10 percent, said Joseph Lstiburek of Building Science Corporation (in the August / September 2011FineHomebuildingarticle,A CrashCourseinR oofV enting).If roofing professionals are not worried about a 10 percent service life reduction, Ridge 9entContinued on page 40www.mrca.orgMidwest Roofer 39'