For over 10 years, the Forest Products Laboratory has been monitoring the temperature histories of roof sheathing, roof rafters, and unventilated attics in outdoor attic structures that simulate typical light-framed construction. This report briefly summarizes findings from the roof temperature assessment project on black and white fiberglass shingles conducted from 1991 to 2001. Temperature histories are then presented for roof assemblies made with western redcedar (WRC), wood-thermoplastic composite (WTPC), and black and white fiberglass shingles and exposed in Madison, Wisconsin, from July 15 to September 15, 2002. The maximum temperatures recorded for the shingles during this period were 68.2°C for black fiberglass shingles, 59.1°C for white fiberglass shingles, 47.1°C for WRC shingles, and 48.7°C and 46.9°C for WTPC shingles with and without lathe, respectively. The black fiberglass shingles were almost 10°C hotter than the white fiberglass shingles and almost 20°C hotter than the WRC or WTPC shingles. Temperatures of the sheathing under the WTPC and WRC shingles were virtually identical and generally much cooler than temperatures of the sheathing under the fiberglass shingles. The sheathing under WTPC shingles applied on lathe was noticeably cooler than the sheathing under WTPC shingles installed directly on felt. The results of this study have implications for the effect of shingle type on the service life of roofing materials and the wood components of light-framed construction.
Winandy, Jerrold E.; Barnes, H. Michael; Falk, Robert H. 2004. Summer temperatures of roof assemblies using western redcedar, wood-thermoplastic composite, or fiberglass shingles. Forest products journal. Vol. 54, no. 11 (Dec. 2004): Pages 27-33