Book Description

To address the problem of defining actual field temperatures of various wood components in wood-framed roof systems, roof temperatures were monitored in test structures situated in the northern and southern United States (Madison, Wisconsin, and Starkville, Mississippi, respectively). The field exposure structures were intended to simulate the attics of multifamily wood-framed structures for which Model Building Codes sometimes allow the use of fire-retardant-treated roof sheathing. The structures were instrumented to monitor interior attic air, exterior air, inner and outer plywood roof sheathing, and internal rafter temperatures in dry whiteshingled structures and both dry and heavily humidified black-shingled structures. Temperatures were recorded from January 1992 through December 1999 in Wisconsin and from January 1996 through December 1999 in Mississippi. The Mississippi exposure generally induced 5ÃC to 10ÃC higher temperatures than did the Madison exposure, though the difference in annual maximum gbs1-h averagegcs temperature of both exposures was usually no more than 3ÃC to 4ÃC. Overall, black-shingled roof systems tended to be 5ÃC to 10ÃC warmer during the midafternoon of a sunny day than were comparable white-shingled roof systems. Few differences in plywood roof sheathing temperatures were noted between dry and heavily humidified structures. Attic airspace and rafter temperatures were generally 5ÃC to 10ÃC cooler in humidified attics than in dry attics. The major difference in the temperature of wood components in the Wisconsin and Mississippi structures occurred during the winter, when temperatures were as much as 20ÃC lower in Wisconsin.