关于屋顶的选择###屋顶的选择和建筑规范屋顶瓦粘土和混凝土瓦屋顶可以安装在实心的护套上，或安装在坡度为2.5/12或更高的屋顶上的间隔护套板上。坡度小于4/12的屋顶需要双层覆盖下垫层(905.3.3.1);坡度为4/12及以上的屋顶需要一层(905.3.3.2)。瓦片附着方法因气候条件、屋顶坡度、衬垫系统和瓦片类型而异。有关适当的附件方法，请参阅IRC第905.3.7节和表905.3.7。应在墙壁和垂直穿孔处设置闪光和反闪光。谷闪必须是至少26规格的“W”型，G90镀锌板，从谷闪中心线(905.3.8)向两个方向延伸11英寸。Slate在2006年IRC第905.6节中有涉及。板岩必须用两颗钉子安装在至少4/12节间距(905.6.2)的实心护套屋顶上，并在下面采用ASTM D 226，类型1衬垫(905.6.3)。有冰坝历史的屋顶区域必须用胶结的两层衬垫粘合在一起，或者用自粘的沥青膜从屋顶边缘延伸到建筑外墙线外24英寸。 Head lap requirements vary with roof pitch and can be found in Table 905.6.5. The minimum standard for valley flashing is 15-inch, G90 galvanized steel of .0179-inch thickness (905.6.6). Asphalt roof shingles Asphalt shingles (Section 905) must be installed on solid sheathed roofs of at least 2/12 pitch with 12-gauge roofing nails long enough to go through the shingle and penetrate the roof deck 3/4 of an inch. Roofs under 4/12 pitch require two layers of underlayment; roofs 4/12 and steeper require one layer. Roof areas with a history of ice damming must have two layers of underlayment cemented together or a self-adhering, bituminous membrane extending from the roof edge to 24 inches…