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Advances in roof membranes In Japan Design Conception and Improving Performance

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Abstract
This paper deals with recent advances in roof membranes in Japan from the viewpoint of the design conception and improving performance. The conventional hot-applied built-up bituminous membrane has been generally improved by the use of bituminous felts made with synthetic fiber base, in addition to an introduction of the spot-bonded system with perforated felts. It is also improved on movement capability and productivity by introducing base sheets made of rubber. In order to eliminate site-melting of bitumen, two types of membranes are developed; one is with bituminous felts with self-adhesive layer, and the other is with site-applied adhesive. The torching system also has been introduced for the same purpose. The watertight performance at lapped joints in the sheet-applied membrane can be improved by laminating two sheets. Several single-ply sheet-applied systems have recently been developed; mechanically attached and a system with stainless steel sheets. Combination of the sheet- and liquid-applied systems improves inherent weak points in each system: the watertightness in lapped joints in the sheet-applied system, and the uniformity of the liquid-applied membranes and their resistance against indentation. The use of a base sheet, which has a grooved pattern on the underside surface for venting, is very effective in improving the capability of liquid-applied membranes and preventing them from blistering. Specially formulated fiber mats also are used for the same purpose as the base sheet with venting groves.
Date
0/1988
Author(s)
Michio Koike
Page(s)
1-17
Keyword(s)
Japan; design concept; performance; advances; sheet-applied; liquid-applied;


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