EXTERIOR WALL FIREPROOF STRUCTURE OF STEEL STRUCTURE

To provide an external wall fireproof structure of a steel structure capable of having the fireproof performance less reduced even at joint part of substrate material and at a joint part of the external wall material.SOLUTION: The external wall fireproof structure of a steel structure comprises a plurality of light steel skeletons 1 long in vertical direction, and on a surface of the light steel skeleton 1, first rectangular gypsum board 2, a second rectangular gypsum board 3 and a rectangular external wall material 5. The first rectangular gypsum board 2 and the second rectangular gypsum board 3 are of same size and both have a thickness of 15 mm. The first gypsum board 2 is fixed to the surface of the light steel skeleton 1 by a fixing member so that two long sides 25, 26 are situated at the light steel skeleton 1 which is a vertical furring edge. The second gypsum board 3 is fixed to the light steel skeleton 1 by the fixing member via the first gypsum board 2 on the surface of the first gypsum board 2 so that two long sides 35, 36 are situated at the light steel skeleton 1 different from the light steel skeleton 1 at which the two long sides 25, 26 are situated.SELECTED DRAWING: Figure 1 【課題】下地材の突き合わせ部及び外壁材の突き合わせ部においても、耐火性能が低下しにくくできる鉄骨造の外壁耐火構造を提供する。【解決手段】鉄骨造の外壁耐火構造は、垂直に長い複数の軽量鉄骨１と、軽量鉄骨１の表面に、長方形の第１の石膏ボード２と、長方形の第２の石膏ボード３と、長方形の外壁材５とを備える。第１の石膏ボード２と前記第２の石膏ボード３は、大きさが同じで厚みがいずれも１５ｍｍである。第１の石膏ボード２は、２つの縦辺２５，２６が、縦胴縁である軽量鉄骨１に位置するよう軽量鉄骨１の表面に固定部材により固定されている。第２の石膏ボード３は、２つの縦辺３５，３６が、第１の石膏ボード２の縦辺２５，２６が位置する軽量鉄骨１とは異なる軽量鉄骨１に位置するよう第１の石膏ボード２の表面に第１の石膏ボード２を介して前記固定部材により軽量鉄骨１に固定されている。【選択図】図１