Abstract
In recent years, elastomeric roofing materials have been introduced because of their excellent mechanical property. These materials are, however, degradated in fairly short time after construction of roof. The purpose of this study is making clear the weatherability of these materials and the roof systems composed of them. The research consists of two works; one is outdoor exposure test in Tokyo and Sapporo, and the other is accelerated weathering tests. Each test was carried out from two different standpoints; One was how the materials were durable, and the other was how the roof systems composed of them were. In this paper, we discuss the changes in mechanical property and the dimensional stability of the materials when exposed outdoors under unrestrained condition. The results obtained may be summarized as follows. Generally speaking, the elongation at breakage decreased and the tensile stress at the elongation rate of 300% increased. Some specimens extended in the early stage of exposure, however, all the specimens showed a tendency to shrink after four year's exposure in Tokyo and Sapporo. The effect of outdoor exposure is severer in Tokyo than Sapporo.
