A self-adhered roof system includes a plurality of waterproof self-adhering base sheets that are self-adhered by watertight bonds to underlying and overlying layers of the roof system and, preferably, waterproof fire-retardant cap sheets that are adhered to an underlying layer formed of the self-adhering base sheets. Base sheet assemblies that each include a base sheet with release sheets overlying its bottom and top major surfaces and, preferably, fire-retardant cap sheet assemblies that each include a fire-retardant cap sheet with release sheets overlying its bottom major surface and a selvage edge portion of its top major surface are utilized to form the self-adhered roof system. The self-adhering base sheets may be used with cap sheets other than fire-retardant cap sheets and with other roof components.